Operation 12

The approximately 8,000m2 covered by Op.12 includes eight surface-visible constructions, most of which are clustered around a patio that is open on the northwest. Structure 1, on the southwest patio flank, is one of the largest platforms in the La Sierra North Cluster and was among the seven edifices excavated during the 1988 (Strs. 1, 3, 6, 7, 15, and 12-Sub7) and 1995 field seasons (Strs. 1 and 15). Operation 12 is bordered by Op. 55, 54, 16, 36, and 31 on the east, south, southwest, west, and north, respectively; these distinctions marking fairly arbitrary divisions of continuous settlement. The terrace summit here is more-or-less flat, the land rising gradually from south to north and west to east. Excavations within Op. 12 uncovered roughly 449m2, the work being directed by M. Dall, C. Eaton, S. Kane, J. Miller, and T. L. Neff in 1988, C. Gevock-Delahaye and S. Escobar supervising the investigations during 1995.

Structure 1 (Figures **-**) [1 section, 1 elevation, 1 plan; D95-63]

Structure 1, one of the largest edifices in La Sierra's North Cluster, closes off the southwestern flank of Op. 12's patio. Structure 15 is 5.35m to the south while Structure 2 in adjoining Op. 36 is 8.5m to the north. The land on which Str. 1 was built is fairly level, dropping 0.14m over a distance of 17.56m west-to-east; the north-to-south ascent is of comparable magnitude. Investigation of Str. 1 was conducted as part of Subop. 12H, 83.3m2 being cleared in the course of excavations conducted from January 30 through March 29, 1995. Digging was carried down to maximum depths of 1.32m below modern ground surface outside architecture and 0.94m beneath ground level into construction fill. This work revealed a single major building phase broken by at least one significant renovation plus the remnants of at least three earlier edifices. All work on Str. 1 was directed by C. Gevock-Delahaye.

Time Span	Construction Phase	Units	Strata	Features	Date
1	-	-	S.1-6	F.1	MPRECL, LCLII
2	Str. 12-Sub1	U.1	-	-	LCLII
3	-	-	S.7	-	LCLII, III
4	Str. 12-Sub2 Str. 12-Sub3	U.2 U.3	-	-	LCLII, III
5	Str. 1-1st	U.4-25, 27-30, 33	-	F.2	LCLII, III?
6	Str. 1-1st	U-26, 31, 32, 34	-	-	LCLIII, II
7	-	-	S.8, 9	F.3	-

Time Span 1

Natural deposition of S.1, a fine textured, hard-compacted, chestnut brown clay containing many small lime fragments, is the first activity attested to off Str. 1's western flank. Stratum 1 dips down 0.21-0.24m towards the center of its exposed 1.06m east-west extent and was revealed to a maximum thickness of 0.43m, its base lying beyond excavation limits. Inclusion of numerous carbon flecks within S.1 may hint at a human presence in the immediate vicinity when this layer was introduced, though this is not established. The depression (F.1) in S.1's upper surface noted above measures roughly 1.06m across east-west, has gently sloping walls, and may have been purposefully excavated prior to the deposition of overlying S.3. There is a concentration of pottery sherds within the declivity's center, their orientations corresponding to the angle of the bordering "walls." Though not entirely convincing, the form and contents of F.1 tentatively suggest that it was a pit intended for use, or recycled, as a trash receptacle.

Stratum 2, a sandy, moderately soft-compacted, tan soil, occupies a comparable stratigraphic position east of Str. 1 to S.1's situation on the west. Exposed to a maximum thickness of only 0.19m (the base was not encountered), S.2 ascends 0.1m over its revealed 0.9m east-to-west extent. Stratum 2's upper surface is 0.36m lower than that of S.1 and the two are quite distinct; clearly there is much that we do not understand about soil changes in the 15.7m separating the two earth levels. No cultural material was retrieved from S.2, though the very small portion of this layer probed during excavation precludes any definitive pronouncements concerning the presence or absence of human settlement in the area when S.2 was naturally deposited.

Overlying both S.1 and 2 is a fine-textured, soft-compacted, tan soil distinguished by the large amount of carbon flecks it contains along with artifacts. Overall, S.3 appears to be the remains of a midden deposited across an extensive area east, west, and, possibly, under the eventual site of Str. 1's construction. On the east, S.3's upper surface undulates slightly over the 0.9m it was uncovered, ultimately dropping a scant 0.04m east-to-west; its western counterpart dips down 0.09-0.16m near the center of its 1.06m exposure, mirroring the general form of F.1 which it covers. Stratum 3's western manifestation is as much as 0.35m above its eastern expression, suggesting, perhaps, that the ground surface during TS.1 ascended this amount over 15.7m east-to-west. Stratum 3 blankets S.1 and 2 by 0.1-0.3m.

Stratum 4, a sandy, moderately soft-compacted, medium gray soil containing both artifacts and carbon flecks, covers S.3 on the east by 0.06-0.22m. The layer's upper surface rises 0.14m over 0.9m east-to west, running up to and under U.1 in the latter direction. Stratum 6, a fine-textured, soft-compacted, tan soil covers S.3 on the west by 0.08-0.23m. Unlike its predecessor, S.6 maintains an even upper level across the 1.06m it was exposed. Stratum 5, a lens composed of a moderately coarse textured, moderately hard compacted, yellowish-red soil, covers S.4 and serves as the foundation for at least the eastern portion of U.1. This level pinches out between S.4 and U.1 on the west, reaching its maximum revealed thickness of 0.09m at the eastern excavation margin. Stratum 5 has a moderately high artifact density, numerous sherds being found in this level. The contents and nature of S.3-6 suggest that they were introduced during an interval of fairly intense human occupation in the immediate area. Most likely, they represent slight variations in trash deposits that accumulated over a protracted period.

A 0.25m high by 1.2-1.3m wide terrace fronts U.7 on the east. The original length of this element is unknown as its eastern facing (U.3) seems to have been truncated on the north during renovations conducted in TS.6; U.3 projects 0.5m north of the eastern stairs, stopping 2.3m shy of U.5 in this direction. South of the staircase, U.3's original line could be traced to its junction with the southern platform facing (U.4). Two cobble surfaces (U.19 and 20) are arranged in a north-south line within the area bounded by U.3, 4, the eastern stairs (U.18), and U.21. The northern component, U.19, covers 1.5m2 and is bounded on the south by a low, 0.2m wide cobble wall (U.23). Unit 20 encompasses 1.4m2 and is delimited by U.3, 4, 21, and 23. Unit 4 is 1.05m wide in this area and may have doubled as a wall foundation and shelf on U.20's southern margin. Units 19 and 20 appear to have been parts of diminutive, stone-paved enclosures (Rooms 1 and 2, respectively) separated by a low cobble foundation (U.23) but open to the east overlooking U.3. The U.19 floor is set 0.1m above t he U.20 pavement. Major modifications of the eastern terrace north of the stairs during TS.6 obliterated most traces of TS.5 construction here.

The eastern steps project 1.8m east of U.3, are 3.5m wide, and consist of at least five stone-faced risers (U.27, 28, 16, 6, and the upper portion of 7). The two lowest steps (U.27 and 28) are fashioned of cut blocks, the basal stones in each element set vertically and topped by flat-laid slabs that form parts or all of the treads. The remaining three components are built using a mixture of cobbles and faced stones, all set horizontally. Stair heights range from 0.18-0.29m while treads are 0.34-1.32m across, the second step being widest (the tread backing U.28). Save for basal component (U.27), treads seem to have been earthen. The fill retained by U.6 is a mixture of small cobbles set in a brown earth matrix (U.33). From the basal to the third step, the staircase is flanked by walls fashioned of cut blocks on the north and south (U.30 and 29, respectively). At the highest (westernmost 0.93m) portion of U.29 and 30, the blocks are set in for courses, vertically set stones (the basal and third rows) alternating with horizontally laid rocks (the second and fourth courses). From the third step (U.16) west to U.7 the flanking walls are built primarily of unmodified river cobbles among which are interspersed a few masonry blocks (U.17 on the north and U.18 on the south). A Spondylus bivalve was cached on the approximate axis of the eastern stairs (F.2). Feature 2 rested directly on the U.1 pavement 0.29m below and directly underneath the base of the bottom-most step (U.27).

Backing U.7 on the west is a 0.51m high cobble wall (U.8) that runs the 2.6m between this construction and the eastern summit wall (U.9); U.8 abuts both U.7 and 9. The 2.6m long space delimited by U.7-9 may have been a room built on the penultimate eastern landing below the summit. Though we are not certain that U.8's base was ever encountered, excavation reached depths sufficient to indicate that the floor of said enclosure would have been at least 0.23m below U.7's base. Either the floor of the putative compartment was sunk below terrace level or U.8 is a fill retaining wall designed to consolidate the platform's earth-and-stone hearting (included in U.33). Though the evidence is far from clear, the second interpretation makes the most sense at present. In that case, the surface backing U.7 would have been at the approximate level of the top of U.8.

Unit 9, marking the eastern summit margin, rises 0.55m above the putative surface of the eastern landing and measures 1.28m across. Unit 13 intersects U.9 and runs for a reconstructed 3.2m westward where it joins U.15, the western summit step-up. Standing 0.55m high, U.13 likely served as a foundation separating a southern enclosure (Room 3), defined by U.9, 11, 13, and 15, from what was probably at least one more compartment on the north (the southern enclosure was completely cleared while no excavation was conducted north of U.13). Room 3 covers 3x3.2m (measured across the center) and has a 1.9m long (east-west) by 0.3m deep indentation set into the approximate center of U.11, the southern foundation. Most of the floor (2.3x2.5m) is covered with a cobble pavement (U.12) that stops 0.3m shy of U.15 and 0.2-0.7m short of U.11; the latter areas are surfaced with dirt. A 0.4-0.5m wide by 0.42m high stone-faced and -surfaced L-shaped bench (U.10) takes up the entire eastern wall of the room (U.9; 2.7m long) and projects 0.7m westward along the northern foundation (U.13). As reconstructed, the Room 3 floor would have been ca. 0.85m below the top of U.9 and 0.36 below that of U.15. Stepping down into the enclosure from the east would, therefore, have been quite a challenge; possibly the bench, U.10, 0.43m lower than U.9's top, acted as a step facilitating passage.

Structure 1-1st, by the conclusion of TS.5, was a platform measuring 10.25x12.35m, rising 1.83m, and aligned roughly 79 degrees. The western flank was ascended by three stone-faced terraces, the north by at least two risers, while the south may have been faced by a single vertical ascent. Renovations to the eastern facade during TS.6 render all reconstructions of architectural form suspect. As best we can discern, the eastern facing (U.7) jogs westward for approximately 1.25m before heading south to intersect the southern basal wall. This step-back was shortened to 0.2m by the construction of U.21 which may have replaced U.22 as the southward continuation of the eastern facing. A 1.2-1.3m wide, low, stone-faced terrace fronts Str. 1-1st on the east. This construction supports two diminutive (1.4m2 and 1.5m2), stone-floored cubicles, arranged in a north-south line, and separated from each other by a cobble footing. Both compartments are open to the east. A 1.25m long by, roughly, 1.05m wide shelf bounds the southernmost compartment (Room 2) on the south. Access to the summit was achieved by ascending a 3.5m wide staircase that projects 1.8m east of the aforementioned terrace. A cache made up of a Spondylus bivalve was interred beneath the approximate center of the eastern stairs. The five stone-faced risers comprising the staircase give way, in turn, to a 2.6m wide, earthen-floored landing. The summit lies west of this landing and contains, at least, two rooms the southern of which (Room 3) covers 9.1m2. An L-shaped bench measuring 0.4-0.5m wide by 0.42m high stretches for 2.7m along Room 3's eastern foundation and projects 0.7m westward along the northern footing. Approximately 63% of Room 3 is paved with cobbles, though a narrow area of dirt (0.2-0.7m wide) borders the enclosure's western and southern margins.

Most extant construction is fashioned of unmodified river cobbles set so that their naturally flatter aspects are oriented outwards. As noted earlier, however, the walls bordering the eastern staircase where it protrudes beyond the limits of the eastern terrace (U.3) are made exclusively of masonry blocks set in alternating courses of vertically and horizontally laid stones (U.29 and 30). The same construction material and style characterizes the two lowest eastern risers (U.27 and 28). Horizontally laid cut blocks are also found mixed with cobbles in U.9, 10, 11, 16, 17, and 24, though in these cases masonry is a minor building constituent. There is a tendency to set the larger cobbles in horizontal courses, filling in gaps around and between these rocks with chinking stones. In those elements fashioned exclusively with cut blocks, the stones are placed in clear courses and chinking pebbles are rare to absent. A brown mud mortar is used as a binding agent in TS.5 construction.

North of the stairs, an extensive L-shaped cobble construction (U.26) takes up most of the terrace surface. The principal stem of this figure runs 2.95m west from U.32 back to U.7 and is 1.7m wide (measured across the center, extending to U.5 on the north). The "foot" of the L intersects the eastern stair at U.17 on the south and is 0.85m wide by 1m long north-south. The unpaved area surrounded by U.26, 30, and 32 encompasses 1.15x1.45m. There is no clear evidence that U.26 was enclosed by footings; rather, the terrace north of the steps appears to have been open on the north and east. Unit 26 may be a bench separated from the eastern staircase by a small earthen-floored space.

Turning to the summit, it may well be that Room 3's floor level was elevated approximately 0.45m during TS.6. Evidence suggesting this interpretation consists of a dense packing of flat-laid cobbles set in a brown earth matrix (U.34) that buries the U.10 bench up to its summit and covers the U.12 floor. It is hard to account for the disposition and density of these rocks through such processes as post-abandonment collapse. Instead, U.34 appears to be a purposefully laid fill that not only raised Room 3's floor but dramatically changed the way in which interior space was used; no bench replaced U.10 in the enclosure's latest version.

Structure 1-1st retained its earlier height and orientation, though it now measured 10.25x 14.15m. The dimensions of Room 3 on the summit were unchanged, though by raising the floor 0.45m, the builders removed all signs of the earlier L-shaped bench. Insofar as the latter construction played an integral role in the activities conducted within the summit compartment, its eradication in TS.6 implies a concomitant change in the functions the compartment was designed to serve. The most significant changes were visited on the eastern terrace which was expanded approximately 1.8m eastward. This addition brought the terrace in line with the eastern steps, the latter no longer projecting from the platform's basal outline. The eastern terrace still supported two stone-paved cubicles south of the stairs (Rooms 1 and 2), though these now overlooked an earthen and cobble-paved surface, respectively. A 1.05-1.15m wide by 2.35m long stone-faced and -surfaced bench/shelf borders the terrace on the south. North of the steps an extensive L-shaped cobble floor covers ca. 5.9m2 and is open to the north and east. The latter construction may have been a low bench facing over a small earthen-floored space (1.7m2) towards the eastern stairs. All architecture assigned to TS.6 is made of unmodified river cobbles placed so that their naturally flatter faces are directed outwards. A few cut blocks are found in U.32 but cobbles predominate in TS.6 architecture. The walls (U.32, U.4- and 5-east extensions) dating to this span are not high enough to recognize horizontal coursing. All rocks are set in a brown mud mortar.

Structure 6-2nd, therefore, is a stone-faced platform at least 0.72m high that is mounted by, minimally, two terraces, 0.2m and 0.17m high by 0.55m and 0.6m wide on the northwest. The edifice measures at least 4.8m northeast-southwest (the western corner was revealed, its northern counterpart obscured under later construction) and is aligned roughly 63 degrees. All facings and pavements are fashioned using unmodified river cobbles the naturally flatter aspects of which are directed outwards. The rocks are set in clear horizontal courses; larger stones are packed round with smaller cobbles that are not as diminutive as most chinking stones. All rocks are set in a fine-textured brown mud mortar. The river-worn stones incorporated in U.1 were apparently selected for their distinctive blue and white colors, a predilection not manifest in later Str. 6 architecture. Rock sizes range from 0.04x0.06m to 0.23x0.25m.

The considerable quantities of cultural material embedded within these layers (especially S. 4 and 6) suggest, at the very least, a significant human occupation in the immediate vicinity while S.3-8 were being laid down. The material in question may have been the product of gradual debris accumulation on and around an abandoned edifice. Alternatively, S.3-8 might represent purposefully deposited fill introduced to raise the living surface northwest of Str. 6 prior to initiating construction of the building's final version. Though we can not distinguish between these possibilities with the data in hand, signs of efforts to elevate patio surfaces, often involving the introduction of large quantities of ash, were recorded in Op. 31 to the north (Strs. 114, 115, and 116). It is plausible, though not established, therefore, that a comparable program of landscape modification occurred off Str. 6-1st's northwestern flank in TS.5.

No sign of such industry is attested to on the southeastern side. Here, at least 0.17m of S.11, a moderately coarse-textured, moderately hard-compacted brown soil, underlies Str. 6-1st architecture (U.9); S.11's base was not found off this platform flank. On the southwest and northwest, S.11 covers final-phase architecture, suggesting slightly different depositional histories for the two sides of Str. 6-1st, located a scant 7.85m apart.

Structure 6-1st's northwestern facade is defined by U.4. Set directly on top of the elevated southeastern portion of U.1, U.4 ascends ca. 0.65m above that earlier entity and 0.62m above S.3 on the northwest. Unit 4 is equally tall where it delimits Str. 6-1st's southwestern flank but here it is set on a portion of U.1 that was still exposed 0.26m above S.5. This would have made the platform's southwestern facade slightly higher than its northwestern counterpart.

By the conclusion of TS.6, Str. 6-1st stood 0.5-0.65m high, measured 5 x 6.9m, and was aligned roughly 60 degrees. The building was ascended on the southeast by two low terraces that provided easy access to Room 1. The latter covers 2.24m northwest-southeast, is paved with stones, and bounded by a 0.24m high, 1.64m wide stone faced bench on the northwest. The northwestern and southwestern facades are defined by steep, vertical ascents set onto U.1. If the northeastern flank is similar to its northwestern and southwestern counterparts, then it would appear that Str. 6-1st's summit was reached from the southeast over the aforementioned terraces. This interpretation matches with the low summit step-up (U.7) on the southeast that may have served as a threshold marking the entryway into Room 1; the northwestern bench probably blocked access to the enclosure from the northwest. All walls and floors are built, primarily, of unmodified river cobbles whose naturally flatter faces are directed outwards. In the steep northwestern and southwestern facings (U.4), the larger stones are placed in clear horizontal courses packed round with chinking stones. The much lower terraces and summit constructions (U.5-7) lack coursing. All rocks are bound by a moderately coarse-textured, brown mud mortar.

Stratum 9, a soft-compacted dark brown soil mixed with ash and pebbles, is exposed in two discontinuous segments. One of its manifestations is as a 0.37m long lens that intrudes 0.07m (maximum) into S.3, 0.1m northwest of U.4. The layer appears again off Str. 6-1st's southwestern flank where it overlies S.5 by 0.06-0.11m. The large quantity of ceramics recovered off the southwestern side and the ash mixed into the northwestern lens suggest that S.9 is the product of cultural activity; the stratigraphic position of both manifestations, near U.4's base atop what was likely ancient ground surface, tentatively indicates that the debris was generated by Str. 6-1st's occupants. Most likely, S.9-southwest was laid down near the end of the edifice's occupation, its included detritus not cleaned away prior to abandonment. Stratum 9-northwest, however, is buried by U.10 and so relates to events transpiring in TS.6 or just at the beginning of TS.7.

Time Span 8

Following Str. 6-1st's abandonment, the building was largely covered by the natural deposition of S.10-12. Stratum 10 is a moderately coarse-textured, moderately hard-compacted, tan soil that accumulated to depths of 0.14-0.18m over S.5 and 0.14-0.28m above S.7 off Str. 6-1st's northwestern flank. On the southwest, S.10 blankets S.9 by 0.09-0.18m. Stratum 10 on the northwest is increasingly orange near its base, this slight color shift apparently resulting from the inclusion of heavily eroded bajareque fragments. Carbon flecks and concentrations are also prevalent near the layer's interface with underlying S.5 and 7. Both carbon and bajareque probably represent cultural material eroding off Str. 6-1st early in the post-abandonment phase. No sign of S.10 was recorded off the platform's southeastern flank. Subsequently, S.10 and almost all final-phase architecture was buried by the introduction of S.11 and 12. These earth layers consist of moderately coarse-textured, moderately hard-compacted soils that are distinguished by the darker brown hue of overlying S.12 and the greater density of small roots in the latter. Strata 11 and 12 collect to total depths of 0.37-0.77m above S.10, being deepest (0.67-0.77m) off Str. 6-1st's southwestern side. On the southeast, S.11 and 12 accumulate to 0.43-0.48m above the base of final-phase architecture (U.9). Architectural debris fallen from Str. 6-1st is found in moderate densities across the building and extending for 1.44m southeast of Str. 6-1st and in light concentrations for 0.5m northwest of the edifice (F.1). Feature 1 rocks are more densely packed across the 0.72m exposed southwest of Str. 6-1st. Here, the architectural debris sits well up within S.11, 0.24m above the S.10/11 interface. This pattern suggests that the collapse of the southwestern facade occurred after S.10 and much of S.11 had already been laid down, perhaps following a relatively protracted interval. Feature 1 is found throughout S.11 on the southeast, down to the base of construction, and on the northwest, though it does not often intrude into S.10 in the latter area. The significance of this apparent differential rate of structure deterioration is not clear.

Structures 3 and 12-Sub7 (Figures **-**) [2 sections, 1 plan; D88-1 and 17]

A fragment of basal wall pertaining to a surface-invisible building was encountered beneath the more-or-less level patio surface immediately northwest of Str. 6 in the trench that cut across the latter edifice. Thinking that we had encountered a small construction intruded into the Op. 12 patio, we pursued the aforementioned trench northwestward in an effort to define the limits of the newly discovered building. Conundrum followed enigma as the work progressed and we found ourselves clearing more and more of the seemingly "empty" patio to make sense of each new unit that was exposed. Finally, after excavating 224m2 (investigations pursued within a continuation of Subop. 12B) we were able to piece together a tolerably coherent account of building activities that spanned three construction phases, three structures undetected prior to excavation, and the western staircase of Str. 3 on the patio's eastern margin. Ultimately all four of these buildings coalesced into a single interconnected set of constructions that filled most of the Op. 12 patio. We never reached the limits of linked architecture by the conclusion of the 1988 field season and it may well be that the entire patio was taken up with low but extensive platforms and related architectural elements. Digging was carried down to maximum depths of 1.32m below modern ground surface outside construction on the southeast (between Str.12-Sub7 and Str. 6) and 0.74m beneath ground level into architectural fill. Excavations were overseen by a wide array of people during the 1988 field season, M. Dall, T. L. Neff, E. Schortman, and P. Urban taking on most of the responsibility.

Note: Because the three surface-invisible buildings uncovered in Subop. 12B northwest of Str. 6 were eventually linked into a single edifice, they are all glossed as Str.12-Sub7. To facilitate outlining their respective construction sequences, each member of the triad is designated by a letter (A, B, and C) following the structure number.

Structure 12-Sub7-3rd is a ca. 0.39m high platform that encompasses roughly 5.3x5.3m (measured across the center) and is aligned approximately 323 degrees. The earthen summit supported a superstructure of uncertain form. Most likely rooms in this building, one of which covers at least 1.1m2, were delimited by low cobble foundations. Facings and footings were made of unmodified river cobbles set in one to two horizontal courses packed round and underlain by chinking stones. The builders showed a predilection for choosing stones that are dark blue in color. The naturally flatter aspects of rocks are oriented outwards. All stones are set in a brown mud mortar. Based on stratigraphic relations observed in the 0.85-1.83m separating Strs. 6 and 12-Sub7-3rd, it seems that the latter was raised at about the same time as Str. 6-1st; its erection and use coeval with Str. 6's TS.6 and 7.

Structure 12-Sub7-2ndB, therefore, is a 0.21-0.31m high stone-faced, earth-and-stone-filled platform that encompasses 5x8.2m (excluding the projection at the northern corner) and is aligned roughly 61 degrees. The earthen summit is largely featureless, though fragments of what may have been stone foundations delimiting a room are located 1.45m southeast of and 3.2m southwest of the northwestern and northeastern basal walls (U.10 and 9, respectively).

Structure 12-Sub7-2ndA is a platform located 3.9m northwest of Str. 12-Sub7-2ndB. The former is bounded by a single 0.35-0.45m high basal wall on each flank (U.18-21; only the northwestern and southeastern ends of the southwestern basal facing [U.21] were uncovered leaving the bulk of this element unexcavated). The earthen-floored summit is featureless. A 0.2m wide, low cobble wall (U.22) extends at least 0.8m northwest from the platform's northwestern facing (U.19). Unit 22 intersects U.19, 0.9m southwest of the platform's northern corner and may have been the foundation for a surface-level building that originally adjoined Str. 12-Sub7-2ndA. Unit 38, a 0.45m high cobble wall found 0.7m southwest from U.19, might be the back of an earlier version of the northeast facing (later replaced by U.19).

Overall, Str. 12-Sub7-2ndA is a 0.35-0.45m high platform that covers 5.2x5.8m and is aligned approximately 336 degrees. No signs of a superstructure survive atop the earthen summit though a surface-level building may have been appended to the platform's norhwestern facing. Structure 12-Sub7-2ndA most likely achieved its final form in several stages as suggested by the identification of a possible earlier version of the northeast basal wall.

Attribution of contemporaneity to Strs. 12-Sub7-2ndA and 12-Sub7-2ndB is tentative, based mostly on their subsequent expansion and coalescence into a single edifice. We can not be certain that these two buildings were raised simultaneously, only that they both served as nodes for later construction whose enlargement was roughly coeval.

All walls and foundations on both Strs. 12-Sub7-2ndA and 12-Sub7-2ndB are made of river cobbles the naturally flatter aspects of which are oriented outwards. Coursing is variably attested to in basal facings, being most clearly represented in U.8, 18, and 20. Chinking stones are arranged around the larger rocks and all cobbles are set in a brown mud mortar.

By the conclusion of TS.5, Str. 12-Sub7-1stB still rose 0.21-0.31m high, retained its original orientation of 61 degrees, but now encompassed 7.2x9.3m. In addition to supporting the room delimited by U.12, the earthen-floored summit also contained two rectilinear depressions set 0.25m below summit level. These entities covered 3m2 and 2.3m2, had earthen floors, and contained no extant constructions. Units 13, 14, 38, and 39 are built of unmodified river cobbles whose naturally flatter faces are directed outwards. The placement of larger rocks in clear horizontal courses is not obvious in any of these constructions. All stones are set in a brown mud mortar and chinking pebbles are placed in the interstices formed between the larger cobbles.

In all, Str.12-Sub7-1stA retained its original height (0.35-0.45m) and alignment (336 degrees) but now encompassed 6.25x8m (not including the northeastern jog in U.23). The featureless earthen summit might well have constituted a single open space. Facings were constructed of unmodified river cobbles the naturally flatter facets of which face outwards. Horizontal coursing of the larger rocks is clearest in U.23 and 25. All of the stones are set in a brown mud mortar and chinking pebbles are packed around the more sizable cobbles.

Structure 12-Sub7-1stB was expanded now by the construction of what appears to have been a stone lined pen against the platform's northwest face (Str. 12-Sub7-1stC). This element is defined on three sides by walls fashioned of cut stone blocks set on end (U.15-17) that stand ca. 0.4m high and abut Str. 12-Sub7-1stB's U.14. The rectilinear entity defined by U.14-17 measures 1.8-1.9m northwest-southeast by 3.3m northeast-southwest, is located 0.25m northeast of U.23 and 0.75m southwest of U.14's putative northern corner, and runs more-or-less parallel to the general orientation of Str. 12-Sub7-1stB (i.e., 61 degrees). The space bounded by U.14-17 measures roughly 1.6-1.7 x 3.1m across the interior. We remain unsure whether U.15-17 are basal facings for an earth-filled platform appended to Str. 12-Sub7-1stB's northwestern flank or stones that delimit a basin that only filled in with dirt and a few cobbles after abandonment. The construction style represented by U.15-17 is unique in the Str. 12-Sub7 complex, though the potential basin form may find a parallel in U.38 and 39 sunk into Str. 12-Sub7-1stB's summit. A brown mud mortar is used to hold together the U.15-17 blocks.

Structures 12-Sub7-1stA and 12-Sub7-1stB maintained their earlier heights and orientations, the former now measuring 6.9 x 8m (without U.36, 6.9x8.85m including that element) and the latter 7.2x9.6m. These buildings, however, had ceased being distinct edifices in TS.6. They now formed part of a single construction that, maximally, encompassed 11.3x16.15m. What had been two separate buildings now appear as components of the same structure, the northwestern most element (formerly Str. 12-Sub7-1stA) offset 2.9m southwest from its southeastern analogue (formerly Str. 12-Sub7-1stB).

Units 27-30 are fashioned of unmodified river cobbles the flatter aspects of which are oriented outwards. Unit 30 appears to have been the most casually built of all constructions unearthed in the Str. 12-Sub7 complex, its constituent rocks being placed in an irregular fashion. A brown mud mortar is used as a binding agent in all walls erected during TS.7 and chinking stones are variably prevalent in the above units.

The Str. 3-1st western steps (U.31-34) overlap U.14, the basal step (U.31) resting on the northeastern margin of Str. 12-Sub7-1stB's summit. Unit 31 is made up of cobbles and is ca. 0.24m tall. The U.31 step is 0.8-1m wide, the tread backing the stone riser having an earth surface, and is succeeded by two risers fashioned of horizontally set cut blocks (U.32-33) succeeded by a fourth built with a combination of cobbles and flat-laid blocks (U.34). Units 32-34 are 0.12-0.22m high by ca. 0.3m wide (preservation of all steps, especially the upper three, is poor, rendering inferred heights and widths tentative). Overall, the U.31-34 steps rise a total of 0.73m, measure at least 2.5m north-south (the northern limit was not exposed), and are aligned roughly 356 degrees. The stratigraphic position of U.31, its base lying at least 0.26m above that of U.15 and overlapping extant architecture (U.14) strongly suggests that these steps are some of the last constructions raised in the Str. 12-Sub7 complex. Quite possibly, this staircase was erected to link Str.3-1st directly with the summits of Str. 12-Sub7-1stA/12-Sub7-1stB. The relatively high position of U.31 vis a vis U.15 implies that the vertically set slabs that comprise the latter only projected 0.15m above ground surface by TS.7. Whether this had been the case in TS.6 when those stones were put in place is not known. All U.31-34 steps are set in a brown mud mortar and the naturally flat faces of cobbles used in U.31 and 34 are directed outwards.

The casual nature of U.19 and 20 construction (see below), coupled with the fact that they abut Room 1 walls and over-ride earlier construction (U.31) may suggest that they were added relatively late in the building sequence. Their placement in TS.2 is, therefore, tentative. The interdigitation of U.19 with the U.16 stone block suggests that these two elements are contemporary and, insofar as U.16 is an integral part of the eastern Room 1 passageway, then U.19 is probably contemporary with the raising of that enclosure. Unit 20 is not so obviously tied to other elements of Room 1 construction; it may be that this vaguely defined entity was appended on to the U.31 shelf well after Room 1 was built, possibly as late as TS.3..

Room 1 faces east into what may have been another earthen-floored summit enclosure (Room 3) delimited by low (0.3-0.4m high) cobble foundations on the east (U.12) and south (U.13). A small stone block (U.14) located at the western edge of U.13 measures 0.34m high, 0.25m long east-west and at least 0.1m wide north-south. Unit 14 may be functionally analogous to the entry features located further to the west (U.15-18), possibly marking a passageway into an unexcavated enclosure south of Unit 13. Room 3's northern foundation was not uncovered, the compartment measuring 1m east-west by, minimally, 0.8m north-south.

Room 2 lies immediately north of Room 1 and is bounded by broad (0.4-0.8m wide) but low (roughly 0.25m tall) cobble foundations (U.5 and 6). Room 2 covers 1.2x2.1m (the western foundation is not clear), has an earthen floor, and lacks preserved built-in furniture.

Investigation of the western projection was limited to a 1m wide trench dug north-south across the approximate center of this entity along with exposure of the element's western face. This work indicates that the projection was mounted by one low terrace each on the north and south. These ascents are delimited by 0.11m high stone-faced risers (U.21 on the north, U.23 on the south) that are backed by 0.64m (north) and 1.66m (south) wide earthen terraces. The latter terminate in stone-faced ascents to the 5.06m wide earthen summit. The northern step-up is barely discernible and probably stood ca. 0.38m high (U.22); its southern counterpart (U.24) is better preserved and stands 0.4m high. The fill packed in between U.22 and 24 consists of small to medium-size river cobbles set in a brown earth matrix (U.30). Units 32 and 33 are two low, 0.55m wide, cobble foundations that extend at least 0.4m west from U.9 onto the projection's summit. Spaced 2.65m apart north-south, these elements are probably foundations delimiting rooms raised atop the western projection. Time did not permit further investigation of U.32 and 33 and we do not know the dimensions of the compartments they may have enclosed.

The western facade is defined by U.25, a 4.75m long (north-south) basal cobble wall to which is appended a shorter (3.4m long), 0.35m wide terrace or step (U.26). Unit 26 is not centered on U.25, but is set slightly south of the basal wall's axis. Affixed to U.26, in turn, is a 0.45m long (north-south) by 0.3m wide cobble block (U.27). Unit 27 is 0.45m north of U.26's southern margin. Units 25-27 are all 0.1-0.12m tall and do not seem to mark a west-to-east progression of increasing heights as would be expected of steps. Lacking such a function, we are at a loss to specify what purposes U.26 and 27 might have served. Unit 25 lines up tolerably well with U.22 on the north, suggesting that these two elements originally joined to form the projection's northwest corner. How the terrace bounded by U.21 relates to U.26 is not known. Units 24 and 25 on the south, however, are not clearly related. This suggests that either: a.) the projection's southern facing (U.24) steps back to join U.25 at some undetermined point; b.) or we had not found the southern limit of U.25 when excavations drew to a close. Unit 23, the southernmost terrace riser, seems to be in line with U.2, its functional analogue on the eastern platform. Such mutual alignments imply, but do not establish, that the basal southern terraces of platform and projection were joined at some point in the construction sequence. Once again, we do not know how the southern terrace relates to the projection's western facing (U.25).

Structure 7-1st's eastern platform is 0.78-0.96m high, measures 8.35x8.65m, and is aligned roughly 340 degrees. Two low, variably broad terraces ascend the building's northern, eastern, and southern flanks giving way to a summit the covers approximately 5.6x6.7m. Raised atop the platform are at least three earthen-floored rooms delimited by cobble foundations. The largest of these enclosures (Room 1) covers 3.9m2, contains two stone-faced benches/shelves, the western one of which may have been L-shaped, and is entered through a formal passageway on the east in which are located for small stone blocks arranged in two pairs. The entry corridor encompasses 2m2 and provides access to another compartment on the eastern summit (Room 3). Only a small portion of Room 3 was uncovered, though the identification of yet another stone block on the enclosure's western margin may signal an entryway to an undiscovered cubicle to the south. Room 2, north of Room 1, covers 2.5m2 and lacks built-in furniture. The benches/shelves in Room 1 are 0.26 and 0.4m high, covering 0.8m2 and 1.5m2, respectively (assuming that the western example, U.20, was L-shaped, as discussed above). The western projection is 0.5m high, covers 7.35x7.8m (the east-west dimension measured from U.25 to U.9), and is oriented approximately 352 degrees. Two terraces flank the projection on the north and south while the western side is mounted by three stone-faced units that increase in length from west to east. The 5.06m wide earthen summit probably supported a complex of rooms defined by low cobble foundations; remnants of two footings were uncovered at the junction with the platform's western flank (U.9). The projection seems to have encountered the eastern platform 1.6m south of the latter's inferred northwest corner while on the south the projection may continue the line of the platform's basal terrace.

All facings and foundations are built primarily of unmodified river cobbles the naturally flatter faces of which are oriented outwards. Cut blocks are incorporated within U.7, 11, 23, 25, and 27, one shaped stone, a fragment from a channel or trough, was included in U.26. Horizontal coursing of the larger rocks is variably represented, being clearest in U.8 and 9, far less evident in the other constructions, including the northern Room 1 wall, U.7. The U.19 and 20 benches/shelves boast the most casual architecture on Str. 7-1st, lacking clear coursing and having very few chinking stones. Elsewhere, chinking pebbles are found packed around the larger rocks in surviving constructions, though they are not equally prevalent in every case. A coarse-textured, brown soil is used as a binding agent in all walls and facings.

Unit 29 is a 0.4m wide by 1.6m long cobble wall that abuts U.7, the northern Room 1 footing, and runs over U.5 and 6. This entity is ca. 0.45m high and probably served as a foundation in a final renovation of Room 2. Contemporary with U.29 is U.34, a 0.32m high by ca. 0.5m wide stone footing that also overruns U.6. Unit 34 is roughly 1.2m west of U.29 and may extend as far as 2.05m north of U.7 (the northernmost 1.1m of U.34 is very poorly preserved and it was almost impossible to distinguish architecture from tumbled debris in this area). Very tentatively, Room 2 now measured 1.2x2.05m, the earlier U.5 and 6 footings having been superseded by this addition. No built-in furniture was recorded within the final, earthen-floored version of Room 2. All three units assigned to TS.3 are fashioned of unmodified river cobbles set in a coarse-textured, brown soil matrix. Construction of U. 28, 29, and 34 appears to be quite casual, there being no evidence of horizontal coursing of the larger rocks and chinking stones are sparingly employed. There is no strong tendency to direct the flatter aspects of rocks outward nor was any effort devoted to modifying the included stones to create such vertical faces. No other significant modifications were noted on Str. 7-1st which retained its original size, form, and orientation.

Time Span 4

Following abandonment, Str. 7-1st was blanketed by natural deposition of S.2 and 3, moderately coarse-textured, hard-compacted soils that are distinguished by overlying S.3's darker brown color and greater density of included roots. Together, these layers accumulated to depths of 0.51-0.71m and covered all but the uppermost segments of final-phase architecture. Moderate to very dense concentrations of tumbled architectural debris were found overlying Str. 7-1st's platform and for at least 0.98m south and 0.76m north of construction (F.2). Feature 2 was not nearly as prevalent off the platform's eastern flank where a light scattering of stones was found extending ca. 0.7m away from the edifice. Fallen stones were equally sparse off the northern, western, and southern sides of the western projection though F.2 increases to moderate densities above the projection's summit.

Structure 15 (Figures **-**) [2 plans, 1 section, 1 burial; D95-1 and 95-79]

Structure 15 occupies the southern corner of the Op. 12 patio. Structure 1 is 5.35m to the north while Structure 120 in Operation 31 lies 102m distant in the same direction. The land surrounding Str. 15 is fairly level, ascending only 0.3m over 11.62m south-to-north. Investigations here were conducted within Subop. 12I, J, and K, fully 72m2 being cleared in the course of completely revealing the building. Excavation was carried down to a maximum depth of 0.84m below modern ground surface outside construction (architectural fill was not probed) revealing two building phases. All work on Structure 15 was directed by S. Escobar.

Time Span 1

A scant 0.05-0.06m of an ashy, artifact-rich soil flecked with carbon (S.1) was found underlying construction directly north and south of Str. 15-1st. This layer resembles strata predating final-phase constructions in the eastern portion of Op. 31. The latter were interpreted as debris purposefully introduced to raise the level of the ground surface, and S.1 may have been laid down as part of a comparable effort. Alternatively, S.1 may be a continuation of the ashy midden deposit uncovered 150m to the west/southwest during the excavation of Str. 16 (see Op. 16). Stratum 1 was not cleared to a sufficient extent, either vertically or horizontally, to determine how it relates to these other deposits. All we can say at present is that the numerous artifacts contained in S.1 and its ash matrix point to a significant human presence in the area where Str. 15 would be erected over the following two time spans.

Time Span 2

Structure 15-2nd is a platform faced on all flanks by cobble walls (U.1, 2, 4, and 7) that ascend ca. 0.6m to the summit. Unit 3 is a 1.1-1.75m wide by 0.54m high stone-faced terrace that seems to have been added after the aforementioned facings were in place. This terrace is retained on the west by a northward continuation of U.2, and has two projections on the north (extending 0.3-0.7m from U.3's principal northern line) that give this flank a crenellated appearance. On the east, U.3 intersects the earlier northern facing (U.7) 0.85m shy of the latter's northeast corner with U.4, creating an inset corner measuring 0.85x1.25m. The summit contains two earthen-floored rooms flanking a central enclosure. The latter, designated Room 1, is surfaced with stone (U.5), covers ca. 7m2, and has a 0.28m high L-shaped, stone-faced bench (U.6) set against most of its northern, and part of its western, walls. Unit 6's largest segment runs 2.1m east-west and is 0.7m wide, a 0.75m long by 0.5m wide projection extends south from its western end. The U.5 pavement seems to be missing over a rectangular space encompassing 0.5x1.2m immediately in front (south) of the bench. Why dirt should replace stone in this sector is unknown. Unit 7 may have stood roughly 0.12m higher where it backed U.6 on the north than it did elsewhere along its east-west extent. Unit 7 also extends 1.4m southward, separating U.6 from the bench in neighboring Room 3 (U.8). These changes in U.7's construction may reflect an effort to shield who/whatever rested on U.6 from view.

Room 3, adjoining the central compartment on the west, measures 3.3m2 and has a stone-faced bench measuring 1x1.4m that takes up most of its northern half (U.8). Like its eastern counterpart, Room 2, Room 3's earthen floor is set slightly below the level of the U.5 pavement. Room 2 is an L-shaped enclosure covering ca. 4m2. The "L" is formed by the westward projection of U.4, the eastern platform facing, 0.9m into what would have been the compartment's northeast corner. This extension measures 1.4m north-south and may have served as a stone-faced bench or shelf.

By TS.2's conclusion, Str. 15-2nd was a 0.6m high platform measuring 5.5x6.3m (including U.3) and aligned roughly 270 degrees, 30 minutes. The superstructure contained three rooms arranged in an east-west line. The central enclosure is paved with stones, covers 7m2, and has a 0.28m high L-shaped bench built against its northern wall. The neighboring compartments have earthen floors, encompass 3.3m2 (Room 3) and 4m2 (Room 2), and each contains a bench or shelf. All walls and floors are built of unmodified river cobbles set in a brown mud mortar. The naturally flatter aspects of these river-worn stones are oriented outwards. Rock sizes range from 0.07x0.1m to 0.42x0.58m.

The southern face is now ascended via two steps, the basal riser measuring 0.2m high by 0.34m wide (U.10) while its successor (U.11) is 0.18m high. Unit 10 is axially located and runs 3.3m east-west; U.11 continues east and west of U.10, acting as Str. 15-1st's 0.38m high southern basal facing. A stone pavement (U.12) covering roughly 4.2m2 occupies the center of the southern addition, lined up with the U.10 step and the U.5 pavement of Str. 15-2nd's central enclosure (Room 1). Unit 12 runs back ca. 1.8m from U.11 where it terminates in a 0.51m high step-up (U.13). Unit 13 is an 0.8m wide cobble construction that spans all but the westernmost 1m of Str. 15-1st's southern flank and buries U.1. Bordering U.12 on the west and east are two earthen-floored rooms (Rooms 5 and 4, respectively). Room 5 is an irregularly shaped compartment that covers ca.1.8m2 and contains no built-in furniture. Its eastern counterpart, Room 4, is the same size, has an earth floor, and lacks clear, preserved built-in features. Rooms 4 and 5 were probably entered through 0.65m wide doorways in their southern walls flanking U.10. Such points of access are suggested by decreases in the height and thickness of U.11 at these points. The southern enclosures, therefore, were surface-level rooms set, within and bounded by, Str. 15-1st's elevated southern terrace, steps, and access feature (U.12). Rooms 1-3 remained open throughout this period and were not significantly modified by TS.3 construction (see the discussion of F.2, below).

Unit 9, which junctions with U.11 and 7 to form Str. 15-1st's southeast and northeast corners, is the new eastern basal facing raised during TS.3. This construction seals off its predecessor, U.4, and expands the platform 0.4m to the east. Extension of the edifice westward was a more complicated affair, at least three sequent additions being made before construction ceased. Unit 14, the first of these additions, runs in front (west) of U.2, beginning at the latter's southwest corner and continuing 5.6m northward where it defines the new western margin of the U.3 terrace. Subsequently, when the major southern addition was made (comprising U.10-13), a new western facing was added (U.15). Unit 15 joins with U.11 at the platform's southwest corner and runs northward in front of U.4 for 5.5m. This left the northernmost 2.4m of U.14 still exposed. Finally, a 1m long addition (U.16) was appended on to U.15's northern terminus in front (west) of U.14. Unit 16 continues U.15's line further north, though 1.4m of U.14 on the north remained uncovered right to the end of occupation here. A cut block (F.1), apparently fractured but in place, was set into the terrace surface backing U.15 near the U.15/14 junction. Feature 1 resembles stones used as entry features elsewhere at La Sierra and throughout the Late Classic Naco valley. Its location on Str. 15-1st's western terrace may mark an ancient passageway into the superstructure. It is, nonetheless, odd that the F.1 stone is not embedded in U.12, in line with the U.10 and 11 steps. There may have been more than one way to enter Str. 15-1st's summit rooms, the steps and F.1 indicating two possibilities, or the cut block may have another significance here.

By-and-large, U.3 was not significantly modified during TS.3. The terrace was expanded 0.35m on the west by the addition of U.14, but no other significant changes were made. Construction of U.9 increased the dimensions of the northeast inset corner, that indentation not covering 1.25x1.25m, while a very shallow indentation measuring 0.35x1.45m is now found on the northwest corner (formed by U.14 and 16). A surface-level room defined by low but variably broad stone foundations (0.4-1m across) was built partially overlapping U.3's northeast corner during TS.3 (U.17). The U.17 footings enclose a space 0.8m wide east-west and at least 0.6m long north-south (the northern margins of the enclosure were not revealed). Construction of U.17 may also have converted Str. 15-1st's inset northeast corner into a formal enclosure open on the east. Unit 17 extends 1.1m east of U.3's northeast corner, sealing off the inset's northern flank. The space thereby enclosed covers 1.1x1.2m.

Structure 15-1st now measures 7.5x7.9m (excluding U.10), stands 0.6-0.89m high, and retains the previous orientation of 270 degrees, 30 minutes. The building contains six rooms arranged in two parallel, east-west rows. In each line there is a central paved space (Room 1 and U.12) that, together, extend the full length of the summit from the southern steps to the U.6 bench. Flanking these formal floors are enclosures whose earthen living surfaces are set below the level of the pavements. The northern examples (Rooms 2 and 3) are fairly large (4m2 and 3.3m2), contain small, stone-faced benches/shelves, and are elevated above ground surface. Their southern analogues are much smaller (1.8m2 each), their floors set on ground surface, and lack extant constructions.

By the conclusion of TS.3, 0.4-0.7m wide terraces border Str. 15-1st on the east and west, The 1.1-1.75m wide U.3 terrace was still exposed on the north, while the southern terrace, fronted by U.11, is 1.8m wide. The superstructure was accessed by means of a formal southern staircase, the basal step (U.10) of which protrudes 0.34m south of the southern basal facing (U.11). Access may also have been achieved by stepping up and onto the western terrace, this entryway marked by the distinct F.1 cut block. A surface-level building, perhaps containing no more than a single, diminutive room, was erected against Str. 15-1st's northern face sometime during TS.3. Construction of this edifice may have also served to transform the platform's inset northeast corner into a small compartment (1.3m2) open to the east.

Foundations, facings, and floors were all fashioned, primarily, from unmodified river cobbles set in a brown mud mortar. The naturally flatter faces of these rocks are directed outwards. In addition to the cut block comprising F.1, masonry was used together with cobbles in that portion of U.11 backing U.10. The latter step was built almost entirely of faced blocks. Some effort seems to have been made, therefore, to concentrate modified stones in Str. 15-1st's entryways. Rock sizes range from 0.12x0.12m to 0.54x0.74m (the latter being a cut block capping part of the U.10 step).

A fine-textured, moderately soft-compacted, tan clay (F.2) was found overlying parts of U.12, 5 and the terrace backing U.3 at thicknesses of 0.02-0.14m (thickest in the area immediately bordering U.6). Feature 2 may represent some element of superstructure architecture that eroded off prior to the general collapse of other construction elements that came to bury the clay (F.3). Alternatively, F.2 may be all that remains of clay originally used to floor the platform's rooms and terrace surfaces. If the latter is the case, then the U.6 bench would only have protruded 0.12m above Str. 15-1st's Room 1 floor. An identical soil was found burying the lower 0.15m of U.10 on Str. 15-1st's southern flank (S.2). The base of S.2 was not encountered. It may be that this clay occurs naturally in the area, providing a ready source of flooring/construction material. Given the similarities between S.2 and F.2, however, we can not exclude the possibility that the former was introduced purposefully to create a formal earthen floor fronting Str. 15-1st's steps.

Time Span 1

Stratum 1, a fine-textured, hard-compacted tan soil (identical to the S.1 described under Str. 7, above), rises out of the base of excavation 0.61m south of Str. 109-1st's basal architecture (U.2). This layer ascends 0.26m over 1.2m before leveling out on the south near Str. 7-1st. Filling in the area between S.1 and the exposed architecture is the lower portion of S.2, a moderately coarse textured, moderately hard compacted, brown soil containing fairly large numbers of pebbles and artifacts. Stratum 2 does run beneath construction here. Recovery of artifacts from S.1 and 2 points to a human presence in the area prior to Str. 109-1st's erection.

The pace and scope of settlement within Op. 12 increases markedly during Late Classic II. All investigated areas were occupied now and there is evidence of substantial construction dating to this interval at Strs. 1, 6, 109, and 12-Sub7. The trajectory maintains its ascent into the Late Classic II/III transition, significant architectural activity being attested to at the six investigated edifices. All but two of these buildings (Strs. 1-1st and 15-1st) achieved its final form during Late Classic II/III. Significant use of Strs. 1-1st and 15-1st persisted into Late Classic III both undergoing major renovations during this period. The remaining four excavated buildings may have been abandoned by now; at least they were not significantly modified during Late Classic III. Early Postclassic occupation within Op. 12 is indicated by the recovery of a very few ceramics distinctive of the period at Str. 7; most likely, a very small remnant population continued to use surviving constructions but did not make noticeable changes to those edifices. The burial set atop Str. 15-1st's final-phase architecture supports this notion of late reuse of extant buildings, probably, in this case, after sufficient time had passed to allow the accumulation of soil over the platform. Unfortunately, this interment could not be dated. There is no evidence of Late Postclassic use of Op. 12.

Operation 12's settlement history, therefore, is characterized by gradual, slow growth in occupation extent and intensity from the Middle Preclassic through Late Classic I. The pace of change accelerates during Late Classic II and peaks in Late Classic II/III when all of the investigated structures were in use and had reached something approximating their final dimensions. Use of the area trailed off during Late Classic III, though Strs. 1-1st and 15-1st remained foci of significant occupation and construction. By the Early Postclassic, population had dwindled considerably and the entire area was most likely abandoned by the Late Postclassic.