Operation 19

Operation 19, in the southwest corner of the North Group, contains nine structures and a surface feature (Strs. 57-65** and Feature **) crowded within a triangular shaped area of land formed by the junction of the Quebrada Danta** with an unnamed northern tributary. Operations 13 and 14 border this agglomeration to the north and northeast, respectively, while the La Sierra Main Group lies a scant 45m** to the south across the Quebrada Danta**. Structures 57-62 surround a patio on all sides save the west, Str. 65** being located in the approximate center of that open space. Structures 63 and 64** lie immediately south of the patio-group, perched on the upper slopes of the steep descent into the Quebrada Danta's** channel. Feature **, a cobble wall that does not project far above current ground surface but is 2.5m wide, intersects Str. 64's** west corner. This construction defines a rough C-shape open to the northeast and parallel to the natural contours formed by the confluence of the Danta** and its northern affluent. The terrain in Op.19 slopes gradually down from north to south towards the seasonal watercourses, the rate of decline increasing sharply as the banks are reached. Approximately 274m2 were cleared in the course of investigating ** buildings in Op.19 from ** to **, 1988 and ** to **, 1990 (Strs. 57-62 and edifices not detected on ground surface, Strs. 19-Sub1- 19-Sub10). Of this number, six were sufficiently cleared to reconstruct their overall dimensions along with something of their final form (Strs. 58, 60, 61, 62, 19-Sub1, and 19-Sub2). The remaining two buildings were only subject to limited investigations. Work here was overseen by D. Schafer, Sonya Kane, and ** in 1988, Neil Ross, J. Douglass, E. Bell, and M. Yeager directing work the 1990 investigations.

Structure 57 (Figures **-**) [1 section, 1 plan; D88-1 and 88-2]

Structure 57 closes off the northwest corner of the Op. 19 patio, lying ca. 10m west of Str. 58 and 25m north of Str. 61. The land on which Str. 57 is raised ascends gradually from southeast to northwest and southwest to northeast away from the banks of the quebradas that delimit Op. 19 on the southeast and southwest. Investigations here were restricted to a single trench (Subop. 19C) measuring 1x3.96m dug against the building's southeast, patio-facing flank. excavations were carried down to a maximum depth of 1m below modern ground surface outside construction (architectural fill was not probed) revealing a single building phase. The work was directed by S. Kane.

Feature 1 is a small pocket of fine-textured, soft-compacted gray ash exposed in S.1 at the base of excavation of Str. 58-1st's southeast side. This deposit was uncovered 0.33m below S.1's top, covers a revealed horizontal distance of 0.36m, is at least 0.05m thick, and is 1.54m southeast of Str. 58-1st's U.19. Undoubtedly, we only encountered a small fragment of a larger ash deposit, though how much bigger this element might have been remains unknown. Recovery of artifacts from S.2, together with F.1, points to a human presence in the immediate vicinity while this soil level was being laid down. This finding conforms to the identification of cultural material within analogous soils that run beneath nearby Strs. 59-1st (S.1), 60-1st (S.4), and 62-1st (S.1). The culturally sterile S.1 sand might found a counterpart in the similar soil deposited prior to revealed construction in the area of Str. 60 (S.1). The latter also lacks signs of human settlement.

Excavations intended to reveal Str. 58-1st's southwest flank encountered a cobble wall (U.3) that was buried by TS. 3 architecture (U.6, 8, 10, 13, and 23). Unit 3 was revealed over a distance of 5.4m northwest-southeast, beginning at roughly 0.25m high on the southeast and stepping up to 0.6m tall 0.9m northwest of the southeastern end. The southeastern terminus was identified while the northwest margin was lost beneath later construction. Unit 3 extends 1m southeast of Str. 58-1st's basal construction (U.4), almost all of it in this area blanketed by S.2. This stratigraphic relation not only points to U.3's temporal priority vis a vis Str. 58-1st's architecture but also implies that the putative platform facing was raised during a break in S.2's deposition. Apparently there was a period following U.3's use when the element was blanketed by continued accumulation of S.2.

Though it is far from clear, U.3 seems to be the northeastern facing of a 0.6m high platform (Str. 19-Sub11-1st) of unknown basal dimensions that is aligned roughly 150 degrees, 30 minutes. Later Str. 58-1st architecture overlaps this basal retaining wall, but extends well beyond it on the northeast where summit architecture rests of fill piled in behind basal walls on the northwest and southeast (U. 4 and 5, see below). By TS.3, therefore, Str. 19-Sub11-1st was no longer a distinct edifice but had become part of a larger construction atop which Str. 58-1st's superstructure was raised. Unit 3 is built of unmodified river cobbles set in a brown mud mortar.

Structure 58-1st is, essentially, a northeast extension of the putative earlier Str. 19-Sub11-1st. The basal retaining walls of this construction (U.4 and 5) stand 0.38m and 0.14m above S.2 on the southeast and northwest, respectively. The northwestern facing (U.5) maintains a fairly straight line over the 3m it was exposed. Unit 4, on the other hand, is characterized by at least one major change of direction over the 3.85m intervening from its point of intersection with U.3 to the northeastern excavation margin. Approximately 1.5m northeast of U.3 the U.4 facing turns and runs southeast for 0.55m before heading northeast once again, this time for 2.8m. A low , stone-faced terrace (U.20) projects 0.75-0.85m southeast of U.4. Unit 20 extends 2.05m northeast from the point where U.4 shifts from a southeast to northeast orientation. This terrace is succeeded immediately on the northeast by yet another addition to U.4 (U.21). Unit 21 is a 1.05m wide northwest-southeast by 1.3m long northeast-southwest staircase composed of four low stone stone risers backed by treads that are 0.2-0.35m wide. The stairs may have been built in two sections, the southwesternmost 0.92m being first, later extended by the addition of 0.38m to the northeast. This renovation, suggested by a change in construction, may have coincided with the northeastward expansion of U.4. The aforemention architectural disjunction in U.21 lines up with what appears to have been U.4's original eastern corner. Unit 21, therefore, was apparently raised as a corner staircase, adjustments in its dimensions being made to maintain this relation to U.4 as the latter was enlarged. The northeastern extention of U.4 covers ca. 0.5m and is abutted by U.24, a low cobble wall that runs over the northeastern margin of U.21. Unit 24 projects at least 0.95m southeast of U.4 (its southeastern end was not clearly identified). The up to 0.3m of dirt separating U.24 from U.21's risers contains a dense concentration of artifacts and bajareque fragments, tentatively suggesting that it consists of midden debris recycled as fill supporting U.24. The last element may be part of a basal facing for Str. 59-1st the surface-visible remains of which lie immediately to the northeast. If this is the case, Strs. 58-1st and 59-1st may have been linked during their final construction stages.

A 0.24m high (above S.2, 0.48m high overall) stone projection (U.19) juts 0.7-0.9m southeast of U.4's southwestern section. Sandwiched between the no-longer visible U.3 and U.20 on the southwest and northeast, U.19 measures 0.5-0.7m wide. Unit 19 is fashioned of cobbles set on end. The 0.5m wide space intervening between U.4 and 20 on the northeast and U.19 was filled with a dense deposit of marine shell (primarily conch) debris.

Access to Str. 58-1st's superstructure on the northwest was by means of a formal entryway bounded by 0.1m and 0.22m high cobble walls (U.15 and 17). These constructions extend 1.85-2.1m southeast from the northwest basal facing (U.5) and border a stone-floored passage (U.16) 1.15m wide. Unit 15 is the higher of the two flanking constructions and is also the most extensive, measuring at least 2.75m across. Its southwestern companion encompasses 1.2m northeast-southwest, ending in the 0.2m rise of U.18. The latter is at least 1.2m wide and extends about 1.5m northwest from Str. 58-1st's superstructure (U.6). Unit 18 may be a shelf and/or bench placed under the eaves of the roof shading the platform's summit.

The superstructure itself consists of three rooms set in a northwest-southeast line and delimited by stone foundations 0.2-0.45m high by 0.3-0.45m wide (U.6-12). A 1.9m wide dip of 0.25m in the top of the northwestern foundation (U.6) lines up with the entry feature discussed above and may have been a doorway leading into the northwest room. A step up of ca. 0.3m from U.16 to the top of U.6 would still have been necessary to negotiate this passage. Feature 2, a fragmented but still articulated cut block is set into the floor of the northwestern room 0.44m southeast of, and near the axis of, the northwestern "doorway." The stone measures approximately 0.6m on a side and may represent an entry feature comparable to those found in other buildings at La Sierra and elsewhere in the Naco valley. A 0.55m wide lowering of the southeastern foundation (U.8) near its southern corner indicates another door, this one providing direct access to the southeastern enclosure.

The northwestern room measures 1.7x4.95m and contains two stone-faced benches (U.13 and 14). Unit 13 is an L-shaped construction that takes up the entirety of the compartment's southwest wall and extends 2.2m along the southeastern foundation. The southwestern component is 0.65m wide, its southeastern counterpart measuring 1m across. Unit 14 is built into the northeastern footing, covers 1.15x1.6m, and continues into the central room. The latter cubicle measures 0.5x1.3m and is entered from the northwestern enclosure through a 0.45m wide door created by a gap between U.10 and the U.14 bench. A total of five polyhedral obsidian cores were found in this space. The central room was created by a 1.96m extension of U.10 (the latter augmentation is indicated by a dramatic construction change) and the raising of U.11 and 12. Walls bounding the central room are relatively shallow, their bases resting 0.2-0.58m above those of the superstructure's perimeter footings (U.7-9). Such relations suggest that the central enclosure is a relatively late addition. Prior to this renovation, movement between the northwestern and southeastern rooms may have been largely unimpeded.

The southeastern enclosures covers roughly 6.4m2 and lacks any built-in furniture. A 0.25m wide "passageway" between this and the central room is located near the latter's southern corner. This gap was filled in near the end of the occupation sequence, access to the central cubicle now only achievable from the northwest.

Room floors seem to have consisted of a foundation of stones mixed with earth. In the southeastern compartment, a 0.07m thick deposit of moderately coarse, soft-compacted, orange soil (F.3) overlies portions of this indistinct surface. Feature 3 may be a remnant of the original living surface or deteriorated bajareque originally derived from the superstructure's walls.

Two low terraces (U. 22 and 23) front the superstructure's southeastern footing (U.8). Unit 22 extends 1.05m southeast of the summit construction's eastern corner, encompassing 2.1m norheast-southwest. Unit 23 is 0.45m further the southeast and measures 0.6-0.95m wide by 2.7m long. The relationship between U.23 and the rest of Str. 58-1st's architecture was not resolved on the southeast, suggesting that this end was either left open (precluding U.23's use as a terrace) or construction here was so poorly preserved that it went unnoticed. Low cobble walls 0.2m and 0.3m wide (U.25 and 26) project 1.1m and minimally 1m southeast and northeast of Str. 58-1st's superstructure, respectively. Unit 25 intersects the summit construction's southern corner (the junction of U.8 and 9) while U.26 disappears beyond our excavation limits from its point of interscetion with U.7, 0.25m northwest of the superstructure's eastern corner. Though only partially investigated, U.25 and 26 seem to be foundations the delimit enclosures that adjoin Str. 58-1st's superstructure on the northeast and southwest.

Structure 58-1st is a 0.14-0.38m high platform built as a northeastward extension of an earlier edifice (Str. 19-Sub11-1st). The edifice's basal northwest-southeast basal dimension is 9.55m, measured across the center and including the U.20/21 projections, and the building is oriented roughly 253 degrees, 30 minutes. Access to the summit rooms was achieved via a corner stairaces on the southeastern, patio-facing flank and along a 1.15m wide, stone-floored corridor bounded by extensive, elevated stone surfaces on the northwest. The aforementioned rooms are delimited by low stone foundations and vary considerably in size. The northwestern enclosure is the largest, covering 8.4m2, and contains two stone-faced benches. An L-shaped bench takes up all of the southwestern and much of the southeastern walls while a second elevated surface is built into the northeastern footing. A 1.9m dip in the northwestern foundation aligned with the aforementioned entry corridor probably marks the doorway into this room, an interpretation that is also suggested by the recovery of a cut stone block set into the compartment's floor on the doorway's approximate axis. The southeastern room is also extensive, encompassing 6.4m2, is entered through a 0.55m wide door in the southern corner, and lacks built-in furniture. Relatively late in the construction sequence, a cubicle measuring 0.7m2 was erected between these two rooms. Originally accessible f rom both the northwest and southeast, the central room's southeastern "passage" was eventually sealed, its contents now apparently retrievable only through the 0.45m wide door on the north. The bench set into the northwest compartment's northeast wall extends into the central cubicle. Two low, possible terraces project southeast of the superstructure while two stone constructions are appended to the platform's southeastern basal wall. One of these, U.19, seems to have been a locale favored for the fashioning of artifacts from marine shell, or at least was a dumping ground for debris resulting from this activity. Yet another bench or shelf appears to have been built under the eaves of the superstructure's roof atop the broad northwestern summit. Additional rooms, delimited by low stone foundations, seem to have been appended to the superstructure's southwestern and northeastern flanks. All foundations and facings are built primarily of unmodified cobbles, their naturally flatter aspects oriented outwards. Feature 2 consists of a single cut block while masonry is incorporated with cobbles in U.17. Horizontal coursing is not clearly attested to in most walls, though chinking stones are fairly common cponents of most foundations and footings. Stones are set horizontally in all cases save U.19 where the rocks are placed vertically. A brown mud mortar was used in all cases as a binding agent.

Time Span 4

Following abandonment, Str. 58-1st was blanketed by the natural deposition of S.3 and 4, moderately coarse-textured, hard-compacted soils that are distinguished by overlying S.4's darker brown hue and greater concentration of small roots. Strata 3 and 4 accumulated to a total depth of 0.3-0.57m over S.2 and covered all but the uppermost stones of Str. 58-1st's architecture. Rocks fallen from final-phase construction were found overlying the building and extending in a light to moderately dense concentration for 1.4m southeast of the platform and 1.02m to the northwest (F4).


Structure 59 (Figures **-**) [1 section, part of Str. 60, and 1 plan; D90-1]

Structure 59, lying 5m north of Str. 60 and 3m east of Str. 58, seals off the northeast corner of the Op. 19 plaza. The terrain here is relatively level, sloping up very gradually from south to north. Only a very limited portion of Str. 59's southeast facing was revealed as a byproduct of more extensive clearing operations conducted on and around Str. 60 (Subops. 19H and I, in particular). Approximately 4m2 of prehistoric deposits were dug in the course of this work, excavations being carried down to a maximum depth of 0.7m below modern ground surface outside construction (architectural fill was not investigated). A single building phase was revealed in the course of this work, overseen by E. Yeager.

Time Span 1

Stratum 1, a moderately coarse-textured, hard-compacted, tan soil, buries the lower 0.33m of Str. 59-1st's southeast basal facing (U.1). It is unclear how much of S.1 was laid down prior to the building's construction and how much accumulated during and after the edifice's use. Recovery of artifacts from all excavated depths within S.1, however, suggests a human presence in the area while this soil level was being deposited, including the period prior to Str. 59-1st's erection. Stratum 1 appears to be a continuation of the earth glossed as S.4 in the Str. 60 excavations (see below, TS.3).

Time Span 2

Structure 59-1st is represented solely by a 1.8m long fragment of its southeast basal facing, U.1. Unit 1 stands 0.31m above S.1, is 0.47m wide, and aligned roughly 62 degrees 30 minutes. A break in construction ca. 1m northeast of U.1's exposed southwestern edge implies that the facing was built in two stages, the northeastern portion apparently being the earlier of the two segments. A cobble surface (U.2) lines up with the aforementioned architectural disjunction, projecting 0.75m southeast of the break in U.1 and then cornering to run at least 0.7m to the northeast. It appears that when U.1 was extended to the southwest the U.2 floor was not expanded. Unit is 1 is fashioned primarily of unmodified river cobbles measuring 0.02x0.05m to 0.13x0.27m. A single cut block, measuring 0.12x0.35m, was incorporated into the northeast side of U.1's architectural break, possibly having capped Str. 59-1st's original southern corner. The larger U.1 stones are set in three horizontal courses and packed round with chinking stones, the latter also serving as the wall's foundation. A brown mud mortar is used as a binding agent.

A 0.04m thick by 0.4m long lens consisting of a dense concentration of ceramics suspended in a moderately coarse-textured, hard-compacted, tan soil (F.1) lies atop S.1 0.49m southeast of U.1. Feature 1 conforms to the northwest-to-southeast downward slope of S.1 in this area and may represent debris deposited near the end of Str. 59-1st's use-life.

Stratum 4, a moderately coarse-textured, moderately soft-compacted, tan soil, buries the bases of architecture pertaining to TS.4 on Str. 60-1st's southwest flank (U.18 and 19). This earth layer was exposed to a maximum thickness of only 0.09m (the base lying beyond excavation limits) and we can not be certain whether it contained cultural material.

Structure 19-Sub2-1st is represented by an 0.11m high cobble wall (U.2) located 0.12m southwest and 0.1m above U.1. Like its predecessor, U.2 appears to have been a foundation defining the southeast flank of a surface-level edifice. Unit 2 was traced from its apparent east corner for 1.5m southwest (oriented approximately 70 degrees). Unit 2 was followed for only 0.3m to the north from the northeast corner. There was no sign of a corner at the footing's southwest end, U.2 simply stopping ca. 0.1m shy of U.3. The latter is a cobble riser built into the northeast-to-southwest slope of the land. Unit 3's base is 0.06m above that of U.2 and it stands to a preserved height of 0.21m. This apparent terrace face was traced for 2.6m northwest from its junction with U.4 on the southeast, though it may well continue beyond excavation limits in the former direction. Unit 3 is aligned roughly 340 degrees. It may be that U.3 served as Str. 19-Sub2-1st's southwest foundation, though only further excavation along the riser's northern extent could help evaluate such a proposition.

On the southeast, U.3 intersects U.4, a 0.1m high cobble wall that extends 1m northeastward between its junction with U.3 and 5. The latter stands a preserved ca. 0.4m high and continues 1.2m southeast to where it joins U.7. The net effect of these connections is the creation of a terrace whose southern end dog-legs to the northeast. Differences in observed height may well be an outcome of variable preservation. Unit 5 rides over the top of U.6, indicating that the former's construction (perhaps the entire U.3-5 complex) postdates the raising of Str. 19-Sub3-1st.

Structure 19-Sub3-1st is an 0.16-0.26m high stone-faced platform defined by single, vertical facings on its exposed northwest (U.6), northeast (U.8), and southeast flanks (U.11). Unit 8 continues at least 1.7m beyond its expected east corner, forming a ca. 0.2m high by 0.95m wide cobble wall backed by U.10 on the southwest and continuing for an undetermined distance to the southeast. There are no clear signs that this wall is a late addition to Str. 19-Sub3-1st. Instead, it appears to have been part of the original construction, though its architectural significance is unclear. Possibly, it defines the southwest flank of a passageway into the area bordered by Str. 19-Sub3-1st on the southeast.

A single room (all of its elements glossed as U.12) was located on Str. 19-Sub3-1st. This enclosure has a rough C-shape, the figure tilting down to the southeast, and its cobble-surfaced floor is set 0.09m below the stone paved summit (the summit pavement is U.9). The cubicle covers ca. 2.1m2 and is delimited by low cobble walls that do not protrude above U.9. Two of these elements rest on the U.12 floor while the remainder extend beneath it. Unit 7 is a substantial (ca. 1.1m wide) wall that rises 0.4m above Str. 19-Sub3-1st's summit. This entity terminates 0.1m southwest of the U.12 enclosure and continues at least 2m southwest to the point where it is abutted by U.5 (U.7 may continue further in this direction, though this was not established by excavation). Units 7 and 12 are the only constructions associated with the use of Str. 19-Sub3-1st's summit during TS.4.

Lying 0.6m northwest of Str. 19-Sub3-1st is a quadrilateral construction fashioned of cobbles and masonry blocks set vertically (U.13). Several of the stones were blackened, as if from burning. Unit 13 measures 1.15x1.36m and contains a fill composed of cobbles, pebbles, and pottery sherds set in a brown soil matrix. (all U.13). The entity stood 0.18m above S.2, its stones projecting down ca. 0.15m through that level and into S.1. A line of three cobbles was set largely within S.1 against the southeastern base of U.13, possibly to enhance the construction's stability on this side. Unit 13's base is 0.14m below that of U.6 while the tops of the two elements are roughly equivalent. The greater depth of U.13's bordering stones may result from the need to wedge these slabs deep within the earth to ensure thaeir stability. Most likely U.13 and 6 were built at about the same time.

Approximately 0.75m northeast of Str. 19-Sub3-1st is a cobble surface (U.14) the base of which is 0.16m above that of U.8. Unit 14 is one stone (ca. 0.1m) thick, runs more-or-less parallel to U.8, and covers roughly 2m northeast-southwest (the northeast edge is eminently unclear). Given the observed stratigraphic relations, it appears that U.14 was introduced after Str. 19-Sub3-1st had been built. It may even be the case, seeing as the top of U.14 is ca. 0.05m above that of U.9, Str. 19-Sub3-1st's summit pavement, that most of the latter building was already buried by S.2 before U.14's appearance. Perhaps U.9 alone remained exposed. Unit 15, a 0.07m thick cobble surface, abuts Str. 19-Sub3-1st's north corner and runs at least 0.6m northeast towards U.14. The base of U.15 is 0.13m above that of U. 8, suggesting that this is yet another relatively late addition. Unit 15 is extends southeastward for minimally 0.53m. Most likely, U.15 marks a southwestern extension of the U.14 pavement, linking the latter with those portions of U.9 that might still have been exposed.

Only two architectural elements found Southwest of Str. 60-1st are tentatively assigned to TS.4 (U.18 and 19). These cobble walls stand at least 0.42m (U.18) and 0.35m high (U.19; the bases of neither entity were uncovered, though they both continue down into S.4) that project 0.58m and 1.74m southwest, respectively, from under Str. 60-1st's west flank (U.33). Units 18 and 19 are separated by a scant 0.37m north-south and may be parts of two closely spaced, contemporary constructions (Strs. 19-Sub4-1st [U.18] and 19-Sub5-1st [U.19]).

Northeast of and downslope from the area eventually occupied by Str. 60-1st, a warren of humble constructions was constructed and modified throughout TS.4. The first identified construction raised in this area appears to have been Str. 19-Sub3-1st. This 0.18-0.26m high cobble-faced and -surfaced platform measures 3m across northwest-southeast by at least 4.4m northeast-southwest and is aligned roughly 248 degrees. A 0.2m high by 0.95m wide wall extends minimally 1.7m southeast from the building's east corner and seems to have been integral to the original construction. Atop the platform, a stone-paved, C-shaped room covering 2.1m2 is set 0.09m below summit level. The only other summit feature is a 1.1m wide by 0.4m high cobble wall (U.7) that runs at least 2m northeast-southwest from a point immediately southwest of the aforementioned room. This wall, wide and long enough to qualify as a bench, rests on Str. 19-Sub3-1st's summit and may be a late addition, possibly contemporary with the next round of construction. Roughly contemporary with the platform is a quadrilateral construction (U.13) measuring 1.15x1.36m that is fashioned of vertically set stones that enclose an artifact-rich earth-and-stone fill. This entity is 0.7m northwest of Str. 19-3-1st and stood roughly 0.32m high. Activities associated with the above unit apparently involved burning as several of the component rocks were charred black.

The bases of Str. 19-Sub2-1st, the U.3/5 terrace, and the pavement extending northeast of Str. 19-Sub3-1st (U.14/15) all rest 0.13-0.25m above those of Str. 19-Sub3-1st and U.13, suggesting that their construction comes near TS.4's conclusion. It may well be that the platform was buried now by the purposeful introduction of 0.18-0.26m of S.2 soil, leaving only its cobble pavement exposed. The cobble surface represented by U.14 and 15 may, in fact, have been laid down in an effort to create an extensive paved area (ca. 7.15m northeast-southwest) that incorporated Str. 19-Sub3-1st's summit. Unit 13 might also have continued to project 0.06-0.14m above this new living surface, though whether it was still used is far from certain. Unit 7, the substantial stone wall found atop Str. 19-Sub3-1st, may also have been raised at this time. Not only does U.7 rest on the platform's summit but it and the southeastern terrace (U.3/5) appear to have been built as a unit. The latter is a 0.1-0.4m high stone facing that was raised near the base of the southeastern slope, probably to slow erosion down that flank. Structure 19-Sub2-1st, a modest surface-level building (Str. 19-Sub2-1st) measuring approximately 1.5m northeast-southwest and oriented 70 degrees, was seemingly built up against this terrace on the northwest. By the end of TS.4, therefore, the exposed area consisted of an earthen-floored patio bounded on the northwest, southwest, and southeast by a: surface-level building (Str. 19-Sub2-1st), low terrace (U.3/5), and an extensive stone surface containing a C-shaped room and supporting a sizable wall near its southwestern terminus. Unit 13 may still have protruded slightly above the newly augmented living surface in the patio's approximate center. Insufficient excavation was undertaken to determine the presence of architecture along the patio's northeast margin.

Further to the southwest, remains of at least two stone constructions were recorded (Strs. 19-Sub4-1st and 19-Sub5-1st). These closely spaced buildings may have been part of yet another complex or an extension of the aggregate described above. Given the restricted nature of excavations here, all that can be said is that identification of Strs. 19-Sub4-1st and 19-Sub5-1st imply a substantial, tightly nucleated settlement that covered very roughly 17m northeast-southwest predated Str. 60-1st's erection.

All TS.4 foundations, facings, and pavements were made primarily from river-rounded cobbles the naturally flatter faces of which are generally oriented outwards. Cut blocks (three), as noted, were used in the construction of U.13, and one appears in Str. 19-Sub2-1st's U.2. Horizontal coursing of the larger rocks was noted on U.18 and 19; the other footings/facings are so low that they render identification of this feature impossible. Chinking stones commonly fill gaps between sizable rocks and a brown mud mortar is used everywhere as a binding agent. Rock sizes (excluding chinking stones) range from 0.03x0.05m to 0.12x0.52m, with most falling towards the middle of that range.

This interval witnessed large-scale infilling northeast of Str. 60. This process begins with S.2's continued accumulation. This earth level eventually blankets Str. 19-Sub2-1st's U.2, the southeastern terrace (U.3), and Str. 19-Sub3-1st; it is not found covering the U.14/15 pavement nor does it obscure U.5. Stratum 2 now ascends 0.25m across 4.64m northeast-to-southwest.

Subsequently, all identified construction is buried beneath a dense deposit of artifacts (mostly pottery sherds) and gravel suspended in coarse-textured, hard-compacted, brown soil matrix (F. 1). Feature 1 ranges in thickness from 0.04-0.34m and slopes down 0.24m across 4.1m southwest-to-northeast and 0.53m over 1.8m northwest-to-southeast (near the northeastern excavation limit F.1 drops only 0.03m1.68m nothwest to southeast). This deposit is especially clear on the northwest where it includes a tightly packed collection of medium-size cobbles measuring altogether 0.37x0.85m. This aggregate sits above U.2's northeast end but is not connected to that construction. The sherds incorporated in F.1 both underlie and slope up towards and down away from the above stones. Feature1 is also thickest immediately behind (southwest of) the cobbles. Taken together, these observations suggest that the rocks were introduced during the course of F.1's deposition, eventually serving as an obstacle to the downslope flow of cultural materials. There is no evidence that the stones in question were part of a formal construction and their presence within F.1 remains an enigma. At the very least, however, the patterned distribution of materials around the cobbles hints at a protracted period for F.1's deposition, an interval in which debris gradually accumulated below and, later, behind an obstruction. Feature 1 is much thinner on the southeast where it collected to depths of 0.04-0.15m over all of Str. 19-Sub3-1st and and lapped over onto the northeastern 0.4m of the U.14 floor. A total of 0.15m of this debris accumulated at the base of the U.7 wall. Feature 1's behavioral significance is unclear and will be dealt with in discussions of activity organization within Op.19. The element's stratigraphic importance lies in its sealing most TS.4 construction, providing a distinctive barrier segregating this architecture from that pertaining to later periods.

Covering F.1 is at least 0.04m of S.3, a coarse-textured, hard-compacted, brown soil containing far fewer artifacts than its nearly identical predecessor. Because S.3 contined to collect after Str. 60-1st's abandonment, it is difficult to ascertain how much of it accumulated during TS.5. The 0.04m figure represents the amount of S.3 intervening between F.1 and the base of Str. 60-1st's northeasternmost architecture. As noted below, ca. 0.3m of S.3 was apparently laid down during TS.5. This discrepancy likely follows from the northwest-to-southeast downward trend of the land, seen most clearly in the relatively rapid fall-off of F.1 in this direction. More of S.3 accumulated on the lower portions of this incline than on its upper reaches.

Units 18 and 19 on the southwest are buried by two very similar soil levels. Stratum 5, a gritty, sandy, moderately soft-compacted tan soil containing some bajareque fragments, covers S.4 by 0.19-0.2m and is, in turn, blanketed by a moderately coarse-textured, hard-compacted, tan earth (S.6) very similar to S.4 and reminiscent of S.3. It may be that S.6 is the southwestward continuation of S.3; both continuing to be deposited in TS.7 after Str. 60-1st's abandonment.

Early on in the process of S.6's introduction, U.20 was constructed. This cobble facing is 0.24-0.27m high and may have been backed over at least 1.23m to the southwest, away from Str. 60-1st, by a stone pavement (included in U.20; this surface is not clear). Unit 20 runs over U.19 and was traced for 1.1m northwest-southeast before limits on time precluded further clearing. Most likely, U.20 is the northeastern basal facing of a 0.27m high platform (Str. 19-Sub6-1st) that is oriented very roughly 339 degrees.

Units 16 and 17 (Str. 19-Sub7-1st) are two poorly understood stone constructions that are set in S.3 northeast of Str. 60-1st. Unit 17 was exposed running for 1.6m at an azimuth of 329 degrees immediately below and northeast of Str. 60-1st's U.21. This construction's base steps down 0.27m over this distance, its stop generally following suit. Possibly, U.17 consists of two heavily disturbed steps or terraces that mount in increments of approximately 0.2m from northwest-to-southeast. If this interpretation is correct, the tread backing the basal step-up 0.84m wide. Unit 16, which extends 1.9m northeast from its near right-angle corner with U.17 at the latter's northwest end, might then represent the continuation of the basal riser in this direction. Unit 16 intersects U.5 on the northeast, that former terrace component possibly serving now as part of the platform's northeast face. The southeastern terminus of U.17 is unclear nor can we be certain that additional portions of Str. 19-Sub7-1st do not lie beuried beneath Str. 60-1st on the northwest. Overall, Str. 19-Sub7-1st is tentatively interpreted as a stone faced platform built into a northeast-to-southwest upward slope, ascended by two low risers on the northwest that rise to a reconstructed height of 0.4m. The building is aligned approximately 329 degrees.

All TS.5 facings are built of unmodified river cobbles, their naturally flatter aspects directed outwards, set in a brown mud mortar. Chinking stones are used sparingly and horizontal coursing of the larger rocks is only tentatively identified for U.20.

Following abandonment of Strs. 19-Sub6-1st and 19-Sub7-1st, roughly 0.3m of S.3 (on the northeast) and 0.24m of S.6 (on the southwest) accumulated. This soil buried all but the uppermost stones of both edifices. The putative stone pavement capping Str. 19-Sub6-1st may have remained visible at the beginning of TS.6, possibly now serving as a pavement fronting Str. 60-1st. Builders of Str. 60-1st's northeastern perimeter used U.17's highest rocks as a foundation for the edifice's northeastern perimeter wall (U.21).

The building's interior is partitioned into three rooms. Room 1, in the east quadrant, encompasses 1.6m on a side, is delimited by cobble foundations on all sides save the southeast (see above, U.21, 24, and 27), and is floored with a pavement comprised of densely packed schist slabs and cobbles (U.25). Units 24 and 21 are 0.76m and 0.46m high, respectively, and protrude an unknown distance beneath the U.25 floor. Unit 27, on the southwest, is much thinner (0.17m wide as opposed to 0.4 and 0.7m across for U.24 and 21) than its counterparts and does not seem to have had a clear back (southwest) side. Rather than being a free-standing, load-bearing wall, U.27 may have faced a 0.24-0.6m high step-down from Room 2 on the southwest. There is an 0.8m wide section in U.27's approximate center where the differences in elevation between the enclosures is only 0.24m, this segment possibly marking a doorway.

Room 2 is an earthen-floored enclosure that covers 1.2x2.2m (estimating where the southern boundary falls based on arguments presented above) and contains a niche (U.29, encompassing 0.5x0.65m) built into its southwest wall (U.28). The U.28 wall is 0.5m high and backed on the southwest by a stone pavement (U.39) extending for 1.9m to U.33. This construction creates a stone-surfaced platform covering 1.9x3.35m (maximum) in Str. 60-1st's south quadrant. The purpose of this construction is uncertain; possibly it functioned as a bench overlooking Room 2.

An 0.85m wide doorway may have breached the northwest room wall (a gap between U.24 and 28 on the northeast and southwest). This passage leads into Room 3. The northeastern segment of this compartment encompasses 1.7x2.3m and has a small (0.3x0.6m, measured across the entrance) niche built roughly 0.20m above floor level into its north corner. A 0.55m high by only 0.22m wide cobble facing (U.23) in Room 3's northeast end defines the margins of an earthen-surfaced bench. This construction is 1.2m wide by 1.9m long, its earth fill retained by U.21, 22, and 24 in addition to U.23. At the opposite end of the enclosure, a 0.2m high by 0.3m wide cobble threshold (U.36) separates the northeastern segment from a much smaller (0.65x1.5m) cubicle on the southwest. The latter is completely paved with schist slabs (U.34). Because we could not located Room 3's earthen floor, we can not say whether it rested at the same level as U.34 or was even with the top of U.36. If the latter was the case, passage into the paved southwestern segment would have involved stepping down ca. 0.2m.

By the conclusion of TS.6, Str. 60-1st was a surface-level edifice measuring 5.15x5.4m, oriented 337 degrees, and containing three rooms. Northwestern Room 3 contains 4.9m2, including the schist-paved cubicle in the southwest but excluding the 0.55m high bench that takes up the entirety of the compartment's northeast wall. Said bench covers 1.2x1.9m and, like most of Room 3, is surfaced with earth. An 0.85m wide door in the enclosure's southeast wall provides access to Room 2. This compartment encompasses 2.6m2 of earthen-floored space and is backed on the southwest by a substantial stone-surfaced construction that is 0.5m high and measures 1.9x3.35m. The general dimensions of this entity suggest its use as a bench. Room 1 contains 2.6m2 of schist-and-cobble-paved space set roughly 0.24m below the reconstructed level of the adjacent Room 2 floor. Movement between these two compartments was through an 0.8m wide door set in the approximate center of their shared partition. Facings and foundations pertaining to this version of Str. 60-1st are made primarily from unmodified river cobbles whose naturally flatter aspects are placed facing outwards. The larger rocks tend to be set in clear horizontal courses packed round with large numbers of chinking stones. Exceptions are U.21's northeast face which, as noted earlier, is casually fashioned and lacks coursing. Unit 27, the facing between Rooms 1 and 2, is built almost exclusively of small, tightly packed cobbles that are not set in horizontal rows. This element's inferred function as a step-down, rather than a support for upper walls, may have reduced the need to incorporate larger stones in its construction. Sizable rocks probably helped stabilize load-bearing walls units. Rock sizes in general range from 0.07x0.1m to 0.19x0.32m.

The Room 1 floor was almost certainly raised during this span, though by how much remains uncertain. Roughly 0.2m of soil stained red, probably from mixture with decayed bajareque, covers U.25 (F.3). Tumbled architectural debris (part of F.4) rests atop this level, implying that F.3's upper surface may mark the level of the TS.7 Room 1 floor. It is also likely, however, that at least part of F.3 represents material eroding into the enclosure soon after abandonment but prior to the onset of major structural collapse. All we can say at present is that the Room 1 living surface had to be raised to accomodate the relatively shallow depth of U.26-northeast, part of that augmentation apparently involved deposition of F.3, but how much of that distinctive earth was introduced while the building was still in use remains uncertain. Wherever the floor may have been, the southeastward expansion of the compartment enhanced Room 1's size to 1.6x1.95m.

Unit 27 continues to divide Rooms 1 and 2, the latter's floor apparently being raised very roughly 0.07m at this time. This interpretation is tentatively advanced based on the presence of F.3 at this thickness in Room 2, the position of F.4 tumble atop F.3, and the position of U.30's base 0.07m above the bottom of the western room wall (U.28). Unit 30 is a 0.15m high stone-faced and -surfaced shelf that now fills the doorway between U.24 and 28. The shelf measures 0.47x1.25m and is backed by a semicircle outlined with cobbles (U.37). Unit 37 measures 0.5m across its exterior dimensions, 0.3m on the interior, across its widest (southeastern) dimension, abuts U.24 and the newly constructed U.38, and is open to the southeast into Room 2. The semicircle's base is surfaced with cobbles (included in U.37). Unit 37 most likely served as a support for a large wooden center-pole that, in turn, was a crucial element in sustaining the roof. Unit 38 is a 0.47m high by 0.35m wide cobble wall that fills in the southwestern portion of the earlier door and continues further in that direction where it intersects U.33 near Room 3's southern corner. Room 2 was now sealed off from Room3, contained a possible bench (including a centrally located niche) along with a small shelf, and measured 1.2x2.2m (including U.30).

Room 3 also came in for its share of remodeling. The entire floor area was raised ca. 0.2m by the introduction of a moderately coarse-textured, hard-compacted, tan soil (U.48). Because U.48 is virtually identical to the earth laid down after Room 3 had fallen into disuse, we can not be sure whether the U.34 pavement was covered now or if it remained exposed. The very top of the U.36 threshold that borders U.34 on the northeast might have remained visible during TS.7. Rising approximately 0.3m above the earth floor northeast of U.36 is a stone-faced, earth-surfaced addition to the northeast bench faced by U.23 (U.47). Unit 47 projects 2.15m southwest from U.23's south corner and is 1m wide. Addition of U.47 further sealed the old doorway into Room 2 and created an L-shaped bench that takes up all of Room 3's northeastern, and about two-thirds of its southeastern, walls.

Returning to Str. 60-1st's exterior, the northwestern foundation, U.32, was extended 0.9m to the southwest (U.42) where it corners with U.43, the new southwest foundation. Unit 43 is 0.4-0.55m high, while U.42 rises no more than 0.25m. The difference in elevation may be a product of differential preservation. Backing U.43 to the northeast is a fill composed of cobbles set in a brown soil matrix (U.46). Unit 46 appears to bury U.33 (the southwestern foundation during TS.6) over the 4.2m north-south distance that U.43 covers. South of U.43, U.33 apparently continued to function as Str. 60-1st's southwestern footing. Unit 43 terminates at its junction with U.41, a 0.33m wide by 0.33m high stone wall that projects at least 1.9m southwest from U.33. Unit 41 does not seem to have been an integral part of Str. 60-1st construction and is probably a foundation for a surface-level building appended on to the main edifice's southwest flank. A conical-shaped intrusion measuring 0.28m across and 0.33m deep is located ca. 0.6m southeast of U.41 and 0.85m southwest of U.33 (F.6). Feature 6's northeast side is steeper and 0.08m lower than its southwestern counterpart, its top sitting at approximately the same elevation as the base of U.41. The architectural significance of F.6 is far from clear, but it may be the remains of a post hole associated with whatever humble construction is represented by U.41. The latter addition was made fairly late in the construction sequence as U.41 rides over U.43. Unit 44 projects 2m northwest from U.41 and rises approximately 0.15m above the earth-and-stone surface backing the new southwestern foundation (U.43). In this area, close to Str. 60-1st's center-line, U.43 and 44 may have comprised a set of steps 0.3-0.4m wide leading to the top of the U.39 "bench." From there, individuals may have stepped down into Room 2 by means of the niche set within that eminence (U.29) or, possibly, into Room 3. In the latter case, as much as 0.57m may have separated wall-top and floor (if U.34 was still exposed), making for a problemmatic passage.

Feature 2 may be the remnants of a perishable construction that was raised above Str. 19-Sub3-1st long after that edifice was abandoned. This element consists of an irregular-shaped expance of burnt earth covering roughly 0.7x1.25m south/southeast of U.7, overlapping the area formerly covered by the U.12 room. A round depression with a diameter of 0.15m found within F.2 may be the remains of a post hole. Roughly 0.13-0.3m of dirt (S.7) intervenes between Str. 19-Sub3-1st architecture and F.2. Either S.7's deposition began earlier off Str. 60-1st's northeast flank than it did elsewhere or F.2 is the decayed residue of an edifice that was erected and abandoned after Str. 60-1st was itself a ruin (S.7 covers portions of Str. 60-1st architecture). Approximately 0.25m of U.7 may still have been visible when the F.2 construction was in use, this substantial wall possibly having been incorporated into the late edifice.

Feature 6 is a purposefully shaped circular stone located 0.47m northwest of U.32's north corner. The stone has a diameter of 0.48m, is fractured, and its top rests at a level equivalent to U.32's base. The architectural significance of F.6 is uncertain. Similar rocks are found occasionally on platform summits where they appear to mark entrances. Feature 6 is the only one of these stones found outside a construction; possibly, it signifies a formal passage into the Op. 19 plaza between Strs. 59-1st and 60-1st.

Structure 60-1st, by the conclusion of TS.7, encompassed 6x7.5m (Including U.40 and 43), retained its earlier orientation of 337 degrees as well as the division of the interior into three rooms. The building was expanded to the southeast by the addition of a 0.31m high platform that may have covered the entirety of this flank. Two low cobble steps apparently provided access to the platform's summit near Str. 60-1st's new east corner. The southwestern foundation was enlarged and two steps may have been set near the building's center to facilitate passage into Str. 60-1st from this side. The floors of all three rooms were raised by the addition of an inferred 0.07-0.2m of dirt. Room 1 in the east lacks built-in features while its southwestern neighbor now contains a low stone shelf in addition to the sizable "bench" that still backs the enclosure on the southwest. Construction of the shelf, together with the addition of one new wall and erection of the building's center-post, effectively sealed the doorway that had previously linked Rooms 2 and 3. The latter now containsan L-shaped bench that takes up just about all of the compartment's available space. How Room 3 was accessed during TS.7 remains a mystery. A surface-level room was seemingly built off Str. 60-1st's southwest flank late in the occupation sequence while a relatively insubstantial construction was raised ca. 3.2m to the northwest in the area previously filled by Str. 19-Sub3-1st. This last entity may not have been built until after Str. 60-1st was abandoned.

Footings and steps dating to TS.7 generally show less care in their construction than those raised in the previous span. River-worn cobbles still constitute the primary building material, though cut blocks were recorded in U.42 near Str. 60-1st's western corner and in U.40 on the southeast perimeter. The naturally flatter aspects of the larger rocks still tend to be oriented outward, though horizontal coursing is no longer as clear and chinking stones are rarer wall components. Unit 42 exhibits an unusual building style, its facing stones not being laid flat but set on end. The ubiquitous brown mud mortar is still the primary binding agent. Stone sizes range from 0.02x0.06m to 0.2x0.4m, with most falling towards the middle to small end of the continuum.

Time Span 8

Following abandonment of Str. 60-1st and its immediate environs, S.3 continued to accumulate against the building's northern corner (this is seen most clearly against U.21's northwestern end). Stratum 3 reaches a maximum thickness of 0.4m where it encounteres U.21's northeast face. Beginning 0.61m northeast of U.21, S.3 is overlain by F.5, a 0.04-0.17m thick level consisting of a dense concentration of pottery sherds and pebbles suspended in a coarse-textured, hard-compacted, brown soil. Feature 5 drops 0.37m over 2.24m southwest-to-northeast before leveling out for the northeasternmost 1.1m exposed in excavations (descending only 0.09m across the latter expanse). Feature 5 also drops 0.16m across 2.87m northwest-to-southeast, eventually coming to rest on top of U.13. This sherd-rich layer rides over F.1 near the middle of its exposed extent, S.3 pinching out northeast and southwest of this interface. In fact, the F.5 artifacts rest atop what appears to be an upward projection of the rock concentration contained within F.1 and described earlier (TS.5). These stones seem to have had an enduring affect on depositional processes in a limited area northeast of Str. 60-1st. Feature 5 could not be traced back to U.21, making it difficult to ascertain the temporal relation between this debris and the building's occupation. Since F.5 appears to terminate on the southwest well up within the mass of tumbled architectural debris derived from Str. 60-1st (0.21m above F.4's base), it is likely that the artifacts it contains were jettisoned after the main building was no longer in use.

Strata 7 and 8 blanket all but the uppermost Str. 60-1st unit. Both are moderately fine-textured, moderately hard-compacted soils distinguished by overlying S.8's slightly darker brown color and greater concentration of small roots. Together, S.7 and 8 collected to a maximum depth of 0.49m. Embedded within S.7 and 8 is a moderately dense collection of stones displaced from final-phase architecture (F.4). Feature 4 is found across all of Str. 60-1st and extends for up to 3.56m southwest and 1.24m northeast of U.43 and 21, respectively.

Structure 61 (Figures **-**) [2 sections, 1 plan; D90-1]

Structure 61 closes off the southwest corner of the Op. 19 patio, lying 25m southeast of Str. 57 and 6m east of Str. 62 (Excavation of Strs. 61 and 62 revealed that they had been connected near the end of their occupation sequence). The terrain here rises gradually from south to north, ascending 0.3m across 9.4m in that direction. Approximately 35m2 was cleared in the course of exposing most of Str. 61's summit along with portions of all four basal walls (Subops. 19B, F, L, N, O, and P). Digging was carried down to maximum depths of 0.6m below modern ground surface outside construction and 0.74m beneath gound level into architectural fill. A single major building phase, associated with at least one episode of significant renovations, was identified in the course of these investigations. All work was directed by S. Kane, N. Ross, and E. Bell.

Time Span 1

On the northeast, the U.5 bench looks out across a 1.6m wide space culminating in a ca. 0.2m drop faced by U.10. This poorly preserved riser marks the southwestern boundary of a 0.76m wide terrace that culminates in the northeastern basal wall, U.2. The terrace surface may have been paved with cobbles, though the evidence is ambiguous. The space between U.5 and 10 may be yet another summit room bounded by U.1 on the south and, possibly, U.3 on the north (giving dimensions of 1.6x3.55m). Unfortunately, the northeastern portion of Str. 61-1st was so heavily disturbed, especially on the northwest, that the form of this enclosure, let alone its very existence, could not be firmly established.

A layer composed of moderately coarse-textured, hard-compacted, orange soil was uncovered running southeastward from U.1 (F.1). Feature 1's top intersects U.10.14m below the latter's top and then slopes down 0.44m over 2.14m northwest-to-southeast underneath TS.3 construction (U.12 and 13). This deposit probably represents eroded building material (decayed bajareque in particular) that derives from Str. 61-1st's superstructure. That F.1 underlies later architecture suggests that the earlier building was allowed to deteriorate somewhat before the last recognized construction phase. Alternatively, F.1 may be building debris introduced as fill to supports TS.3 renovations.

Overall, Str. 61-1st is a 0.51-0.7m tall platform measuring 3.8x6.6m, aligned roughly 61 degrees. The summit supports a substantial bench standing as much as 0.55m high and covering 1.8x2.7m. This construction bounds a stone-floored room on the southwest that encompasses 3.1m2. A compartment measuring 0.5m2 is off the room's north corner and a 0.53m wide door set in the western corner provided access to the interior space. Yet another enclosure may have been located northeast of the bench, this one measuring as much as 5.7m2, though the evidence for this compartment is far from clear. A single, low, cobble-faced terrace ascends the edifice's northeast flank; no comparable elements were noted elsewhere on the platform. Foundations, facings, and the U.11 floor were all fashioned from unmodified cobbles set in a brown mud mortar. In most cases, the larger rocks were chosen for their naturally flatter aspects, which were placed facing outwards, and set into as many as four horizontal courses packed round with chinking stones. Unit 6 has relatively few chinking pebbles as does U.10, while U.7 not only has very few of these small rocks but lacks clear coursing and its stones were not selected for their flat faces.

A 1.75-2.3m wide terrace was appended onto Str. 61-1st's northeast flank relatively late in the construction sequence (U.20). Unit 20's northeast face stands a preserved ca. 0.3m high and has a follows a fairly irregular line that generally steps back to the southwest over its uncovered 2.65m northwest-southeast length. On the northwest, U.20 joins the U.9 extension (described under Str. 62, TS.3) the latter now defining the terrace's northwest flank. Unit 20's southeastern terminus was not identified, though it was traced to a point approximately 0.5m northwest of Str. 19-Sub7-1st (see below, Str. 62). It is very likely, therefore, that U.20 was not much longer than its exposed 2.65m. This late northeastern terrace, therefore, would not have run the full length of Str. 61-1st's northeast flank but stopped roughly 1m and 1.45m short of the platform's eastern and southern corners, respectively. Unit 20 is backed by a fill composed of densely packed cobbles set in a tan to brown soil matrix (U.21). There is no clear evidence for a formal floor capping the U.20/21 terrace. Unit 14, Str. 61-1st's northeast basal facing during TS.3, would still have protruded ca. 0.1m above U.20.

Unit 16, a ca. 0.2m high wall, seems to have been the riser for a 1.45-1.6m wide terrace fronting Str. 61-1st's northwest flank. Extending 1.25m west from Str. 61-1st's south corner is U.22, a 0.25m high by 0.36m wide cobble wall (U.22). Unit 22 abuts U.15 and is most likely the remains of a foundation for a surface-level construction raised against Str. 61-1st's southwest flank.

Structure 61-1st, by the end of TS.3, covers 5.5x7m (excluding the U.16 and U.20/21 terraces), retains the earlier orientation of ca. 61 degrees as well as its height of 0.51-0.7m. All sides were now ascended by at least one stone-faced terrace, three risers facing the building's northeastern flank. The summit bench was considerably enlarged, now encompassing 2.6-2.7m by at least 2.7m and, perhaps, as much as 3.9m. The northeastern room was reduced in size commensurate with expansion of the bench, now covering 2.5m2. The southwestern enclosure may have been expanded slightly to the southeast, but was otherwise unchanged. This compartment encompasses ca. 4m2. The broad southeastern terrace may have supported one or more rooms delimited by cobble foundations, in addition to construction related to the summit enlargement, but the numbers, forms, in fact, the very existence, of these enclosures were not established. A surface-level edifice may have been raised against Str. 61-1st's southwest basal facing near the close of TS.3. The net result of the renovations that define TS.4 was an increase in the elevated living area associated with Str. 61-1st and heightened crowding along the Op. 19 patio's south flank. Structures 61-1st and 62-1st may have been joined at this time and a small construction (Str. 19-Sub7-1st; see below, Str. 62) may have been sandwiched in between these adjoining edifices.

All foundations and facings are made primarily of unmodified river cobbles, the naturally flatter aspects of which face outwards (U.22's stones were not apparently selected for their flat faces). The larger stones are generally set in horizontal courses and packed round with chinking stones. Clear coursing is absent U.22 and the northwestern half of U.20, whereas chinking stones are uncommon in U.16, 23, and the southern half of U.20. Chinking stones comprise foundations for U.12, 14, and 15. A brown mud mortar is used as a binding agent in each case.

Stratum 1 is a moderately fine-textured, moderately hard-compacted, tan soil that underlies all construction. The limited portion of S.1 exposed in our excavations (ca. 0.05m deep) was insufficient to determine whether this layer contained cultural material that was unlikely to have percolated down from later deposits. A very similar soil (S.1) found underlying Str. 62-1st architecture immediately to the northeast did contain artifacts, however, implying a human presence in the immediate area while S.1 was being laid down. Stratum 1 in the vicinity of Str. 19-Sub9 is a continuation of S.1 identified to the northwest under and around Str. 61 and, most pribably, S.1 uncovered Str. 62's environs.

Overall, Str. 19-Sub9-1st is a surface-level building that encompasses 4.55x4.9m (maximum) and is oriented very approximately 61 degrees. At least one, 1m-wide door built into the southwestern footing, and shielded by a low cobble wall on the southeast, provides access to the interior. The latter space was not cleared and so we can advance no suggestions as to how many rooms Str. 19-Sub9-1st may have contained or how these were floored and furnished. Stratigraphic relations suggest that Str. 19-Sub9-1st was raised at about the same time as the renovations conducted on adjacent Str. 61-1st (TS.3); the adjacent basal/perimeter walls of both buildings (U.13 and 7) are set within and rise above S.1, the base of Str. 19-Sub9-1st's U.7 being ca. 0.1m below that of Str. 61-1st's U.13. This difference is commensurate with the general southeast-to-northwest slope of the local terrain. Unmodified river cobbles, their naturally flatter faces directed outwards, are the primary stones used in constructing Str. 19-Sub9-1st's foundations. The larger rocks tend to be set in horizontal courses and are packed round with chinking stones. Units 4 and 6 lack clear coursing while chinking pebbles are uncommon in U.3. A few cut blocks are intermixed with the cobbles in U.6 and 7; no consistent pattern was noted in their placement within these footings. A brown mud mortar serves as a binding agent in all foundations.

Structure 62 (Figures **-**) [3 sections, 1 plan; D90-1]

Structure 62-2nd is represented solely by U.1, a 0.46m high, 0.3-0.45m wide stone wall that runs 1.84m northeast-northwest (82 degrees, 30 minutes) from U.8 before changing to a northeast-southwest orientation (238 degrees) for the remaining 4.75m it was exposed. The latter stretch was revealed in three discontinuous segments. Unit 1 runs beneath architecture raised during Ts.3 and 4. The wall's eastern and western terminii are not clear and it is likely that the entity continues southwest of the furthest point revealed in our excavations. On the southeast, it appears that U.1 stops at U.8 (though the latter postdates the former) but excavations were not continued to a sufficient depth to permit definitive confirmation of this supposition. Unit 1 is set on S.1 and is fashioned of medium to small cobbles that are not set in horizontal courses. Stone sizes range from 0.05x0.11m to 0.12x0.22m and all rocks are set in a tan mud mortar. Chinking stones were not used nor was much effort apparently expended during U.1's construction in locating rocks with flat faces (or modifying them to achieve such aspects). Unit 1's top is 0.26m lower than it is elsewhere beginning at the change of direction noted above and continuing for at least 1m southwestward where the element runs beneath U.6. This change in elevation apparently results from stone modifications visited on U.1 during TS.3.

Ultimately, Str. 62-2nd appears to be a 5.59m long (minimally), 0.46m high cobble wall that is variably oriented 82 degrees, 30 minutes and 238 degrees. Though the evidence is far from clear, Str. 62-2nd seems to be a free-standing wall possibly designed to close off the Op. 19 patio's southern flank.

Structure 19-Sub8-1st, consisting of U.17's revealed portions, is 5.4m northwest of Str. 62-2nd. Unit 17 is a 0.37m tall by 0.57m wide cobble wall that was exposed running at an azimuth of 242 degrees, 30 minutes for a distance of 2.65m. The entity's eastern corner was unearthed, a segment of cobble wall projecting 0.85m north/northwest of U.17's apparent northeastern end (both wall portions included in U.17). Structure 19-Sub8-1st's southern corner was not identified. Like U.1, U.17 is set on S.1, its base lying 0.26m below that of U.9, 1.4m to the southeast. Though the relationship between U.17 and later construction is less obvious than was the case with U.1, these stratigraphic relations strongly argue for inclusion of U.17 in TS.2.

Structure 19-Sub8-1st may have been either a surface-level construction or low platform aligned roughly 242 degrees, 30 minutes. In either case, it appears to have been a relatively modest construction. The edifice's basal walls/foundations are built of unmodified river cobbles the naturally flatter faces of which are directed outwards (southeast and northeast). The larger rocks are placed in two-to-three horizontal courses packed round with chinking stones. A tan mud mortar is used as a binding agent. After Str. 19-Sub8-1st's abandonment, much of its southeast flank was buried a segment of S.1 soil rich in cultural material. This ca. 0.3m thick deposit includes large quantities of pottery sherds, bajareque fragments, conch shell debris, and carbon flecks. The geneally southeast-to-northwest downward tilt to the embedded artifacts implies that the material was introduced into the area from the former direction. Roughly 0.07m of U.17 might still have projected above S.1 after deposition was completed.

Approximately 0.05m of S.2, a coarse-textured, hard-compacted brown soil containing numerous small pebbles (3mm or less in diameter), was laid down atop S.1 prior to the initiation of TS.3 construction.

Room 2 borders the aforementioned enclosure on the northwest and is delimited by U.2, 6, 8, and a portion of U.1. Unit 1 was reduced in height by 0.26m along a 1m long stretch between U.6 and the point where U.1 turns to the southeast. This 1m long segment of U.1 would now have been barely visible above floor level. The remaining 1.84m of the wall, now protruding about 0.26m above the living surface, divides Rooms 2 and 3. The above modifications created a doorway connecting these two enclosures. Passage into Room 2 from extramural areas was through a 0.5m wide entryway set into the enclosure's east corner. No built-in furniture was identified in Room 2 though the 2.35m long segment of U.2 backing the compartment on the southeast is wide enough (1.05m across) to have functioned, in part, as a bench. Unit 6 on the southwest is also sufficiently substantial (1.7m long by 0.9m wide where it borders Room 2) to have been used as a bench. Units 2 and 6 are are 0.53m and 0.26m high respectively. Room 2 measures 1.05-1.65m northwest-southeast by 2.5m northeast-southwest.

Room 3 borders Room 2 on the northwest and is delimited by U.6, 8, and 9. The enclosure measures 2.4x2.6m and was entered through a 0.72m doorway in the northeast foundation (U.8). Room 3 contains no obvious built-in furniture, though the 1.5m long segment of U.6 that defines the compartment's southwest flank is wide enough (0.9m across) to have served as a shelf and a support for perishable upper walls.

Room 4 lies immediately west of Room 3, passage between the two enclosures being through an ample (1.4m wide) gap between U.6 and 9. Units 6, 9, and the northwestern 0.85m of U.12 border Room 4 on the southeast, northwest, and southwest, creating a diminuitive space covering approximately 1.3m on a side. The only construction found within Room 4 is a stone-lined and surfaced square built against U.6's northwestern edge (U.7) in the gap between that wall and U.12. Unit 7 measures roughly 0.6m on a side and its walls rise 0.08-0.12m (equivalent to one stone's thickness) above the large cobble that serves as the floor. That stone encompasses 0.3x0.4m, virtually filling the interior. A distinctive orange soil is concentrated in the northeasternmost 0.15m of U.7, resting on and extending for 0.06m above the floor. A very red earth, most likely derived from decayed bajareque, is found on U.7's southeast margin. A large fragment of this material is integrated into U.7's east corner. Large quantities of artifacts, especially marine shell fragments, were recovered from U.7's floor and immediate environs. Unit 7's walls do not seem substantial enough to have stood above Room 4's living surface; more likely, this square was recessed 0.08-0.12m below the enclosure's floor.

Structure 62-1st's northwestern footing (U.9) extends for at least 1.85m southwest of its junction with U.12 and most probably covered the additional 0.75m to link up at some point with Str. 61-1st. Whether this extension was effected in TS. 3 or 4 is uncertain. We were not able to discern a significant change in building style that might have marked a late addition to U.9. This observation implies that U.9 was built as part of a single effort. Nevertheless, the foundation is characterized by a casual construction style that thwarts efforts at recognizing breaks in its construction. For the moment, therefore, U.9 in its entirety is included in TS.3, though we strongly suspect that the portion southwest of U.12 was added later during the northeastern expansion of Str. 61-1st (U.9 in this area serves as the northwest facing for a terrace extending northeastward from the latter edifice; see above). Unit 11 is a 0.27m high block of stone integrated with and protruding 0.15-0.3m northwest of U.9's southwestern extension. The construction measures 0.35m across and its top is 0.13m below that of U.9. Unit 11 is, most likely, a step facilitating access to Str. 61-1st's northeastern terrace.

Unit 1's fate within Str. 62-1st has been discussed above. As the building's southwest perimeter wall, U.6, runs over the top of U.1's dismantled portion, it is almost certain that the earlier wall was at least partially demolished to make way for U.6. Starting immediately southwest of U.6, however, U.1 was apparently maintained at its original height for at least 2.86m. Unit 6's southwest face rests on top of U.1, strongly suggesting that the latter construction was buried under as little as 0.2m and as much as 0.36m of a brown earth fill (U.19) during TS.3 (the uncertainty in fill thickness results from our inability to determine how much of U.1 originally stood above ground surface and how much was intruded beneath that level and the virtual identity of U.20 and overlying S.2 ). The living surface southwest of U.6 would, therefore, have been elevated ca. 0.2m above the Room 2 floor. The situation further to the northwest where U.6 borders Room 3 is unclear, though U.12's northwestern segment was apparently not set on such elevated terrain.

By the end of TS.3, therefore, Str. 62-1st is a surface-level edifice that measures 8.5m northwest-southeast by 6m (on the southeast) to 5m (on the northwest) northeast-southwest (excluding U.9's southwest extensions and steps set against that entity and U.4). The building is oriented roughly 151 degrees by 250 degrees, 30 minutes and contains four earthen-floored enclosures. Rooms 1-3 are arranged in a southeast-to-northwest line, and Room 4 situated off Room 3's west corner. The enclosures cover 9.3m2, 3.4m2, 6.2m2, and 1.7m2 respectively. One or two particularly substantial walls bordering Rooms 1-3 may have doubled as foundations and benches/shelves. A stone-lined and -surfaced square in Room 4 is sunk 0.08-0.12m below Room 4's floor and is associated with a bajareque upper construction and large quantities of exotic (i.e., marine shell) debris. Access to Str. 62-1st's interior was through doors set into the footings of every room save 4; Room 1's entryway was apparently changed from a corner passage to a step-up over its southeast foundation. Movement between Rooms 2, 3, and 4 was through wide doorways, but it is not clear how, or if, Room 1 was accessed from inside Str. 62-1st. Though the evidence is ambiguous, introduction of 0.2-0.36m of earth fill southwest of Str. 62-1st created a living surface in this extramural zone ca. 0.2m above that found in Room 2 to the southeast.

The primary building material used to fashion constructions associated with Str. 62-1st is the unmodified river cobble. Cut stone blocks are occasionally mixed with these river-worn stones, being found in U.4, 6, 8, and 11. There is no consistent pattern to the placement of masonry within the above foundations. In general, cobbles with naturally flat aspects were chosen for inclusion in construction, these faces oriented outwards (U.8 is an exception). The larger rocks are set in horizontal courses within U.2, 3, 5, 6, and 12; such systematic stone placement is not attested to in the other elements. Chinking stones are used to fill in gaps between sizable rocks in all foundations, though nowhere are they very common. Units 2 and 6 are built with the largest number of chinking pebbles, U.8 has the fewest, and the remaining components occupy intermediate positions within the continuum. A brown mud mortar is used as a binding agent in all units.

No significant changes were noted in the other emclosures. A ca. 0.2m high wall may have extended 0.92m northwest into Room 1 from U.4's approximate center (F.4). Further clearing did not establish F.4's validity; if it was a purposeful construction it was remarkably casual.

The major constructions assigned to this interval are located on Str. 62-1st's southwestern margin. Here, U.12 was extended 2m southeastward, paralleling and only 0.25m southwest of, U.6. This addition to U.12 is marked by a clear change in construction and the elevation of the footing's base by ca. 0.2m. The latter observation suggests that U.12 was now being raised over elevated terrain, a change that most likely resulted from the introduction of earthen fill either during TS.3 or now. Unit 12 joins with U.13 on the southeast, the latter resting on an upward augmentation of U.20's brown earth fill. Roughly 0.15m of this soil were added now, leaving only 0.05-0.1m of U.6 still visible on the southwest. The same vertical relationship pertains between U.6 and U.12's southeast extension. Unit 13 overlaps the southeast end of U.12-southeast and projects an additional 1.8m southeast to an abutment with U.2. Units 12-southeast and U.13 are ca. 0.3m high by 0.2m (U.13) to 0.64m wide (U.12-southeast) foundations that now define the northwest segment of Str. 62-1st's southwest flank. Unit 12-southeast apparently supplements or replaces U.6 in this capacity while the U.13's construction created a compartment bounded by U. 2, 6, and 13 (Room 5). Room 5 measures 1.15x1.55m (across the center), has an earth floor, and lacks built-in furniture. Unit 6, still barely visible on the northeast, might have been a bench shared by adjoining Rooms 2 and 5 (see above, TS.3). Feature 3 is a level of bajareque fragments found directly underlying U.12-southeast and U.13. The significance of this layer is eminently unclear; it may suggest that perishable constructions erected southwest of Str. 62-1st during TS.3 were leveled prior to raising that building's TS.4 architecture.

Structure 62-1st's form and dimensions are largely unchanged from TS.3. Raising of living surfaces southwest of U.6 apparently continued along with the creation of a fifth enclosure southwest of Room 2. This new room covers approximately 1.8m2 and may have been accessed by passing over U.6 from Room 2. Further northwest, U.12 was extended southeastward; U.12 and 13 now defining the building's southwest perimeter. Room 4's doorway into Room 3 was formalized by the addition of a doorjamb adjoining U.9, the northwest foundation. The U.7 stone-lined box was apparently blanketed by the introduction of earth fill designed to raise Room 4's floor by ca. 0.1m.

Structure 19-Sub7-1st is an enclosure measuring 1.25m northeast-southwest by minimally 1.4m northwest-southeast (its southeast flank was not found) situated 0.65m southwest of U.13. The walls delimiting this entity (U.14-16) are alligned roughly 228 degrees, stand 0.2m high, and ride 0.05m above the top of U.1. Units 14-16 are equivalent in depth to U.12-southeast and U.13, resting on the same U.20 fill, indicating that Str. 19-Sub7-1st is a relatively late construction wedged in between Strs. 62-1st and 61-1st on the east and west. It is unclear whether Str. 19-Sub7-1st is a low platform or a surface-level construction.

Time Span 4 architecture is fashioned from unmodified river cobbles set in a brown mud mortar. The naturally flat aspects of these river-worn stones are generally placed facing outwards. Horizontal coursing is not pronounced in any of these elements and chinking stones are relatively scarce.

Use of the Op. 19 began in earnest towards the end of Late Classic I and the beginning of Late Classic II. Material dating to this span is clearly attested to within a tan soil underlying architecture at Strs. 57 and 58 (assignment of preconstruction levels at Strs. 61, 62, and 19-Sub9-1st to Late Classic I/II is based on the presence of similar soils deposited prior to building activities in each case and the close proximity of these edifices to Strs. 57 and 58). Structure 19-Sub1-1st, apparently a relatively insubstantial surface-level building, may have been raised now northeast of Str. 60. Late Classic I/II occupation, therefore, seems to have been widespread throughout the Op. 19 plaza area associated with the erection of humble buildings.

All the rest of exposed architecture was built and used during the period that spanned Late Classic II and the early part of Late Classic III. The Op.19 plaza took its final form at this time and supported a population of significant size busily engaged in constructing and renovating structures of varying sizes and forms. The concentration of so much building activity within this period implies that Op. 19's residents were participants in dynamic processes that spurred a rapid sequence of changes in the organization of spaces for living and working.

How long settlement in Op. 19 persisted into Late Classic III is uncertain. The plaza, at least, was apparently abandoned by the Early Postclassic and their is no sign of subsequent occupation throughout the remainder of the prehistoric and all of the historic periods.