Medicinal Trail Reservoir (Operation 10)

The Medicinal Trail Reservoir, designated Depression A-3, is located adjacent to Group A, the largest settlement group identified at the site (Figure 3). Defined as a First Tier Household, a formal courtyard group composed of multiple structures with complex basal platforms, Group A consists of six mounds organized around three contiguous courtyards with the largest construction placed on the east side of the group (Hageman and Lohse Reference Hageman, Lohse, Scarborough, Valdez and Dunning2003; Hyde and Atwood Reference Hyde, Atwood and Valdez2008; Hyde and Valdez Reference Hyde, Valdez and Valdez2007). The depression itself is situated 40 m northeast of the center of Group A and fewer than 10 meters south of Structure A-7, and is roughly ellipsoidal in shape. Initial support for Depression A-3 serving as a water tank was based on its surface area, estimated capacity, and location adjacent to a probable residential structure (Structure 7). The shape, potential volume (accounting for sedimentation and soil formation over time), and calculated surface area fit the profile of other topographical depressions investigated as water resources in the central Maya lowlands (Weiss-Krejci and Sabbas Reference Weiss-Krejci and Sabbas2002). In addition, the proximity of the depression to several agricultural terraces and additional house mounds, coupled with the absence of any permanent water sources in the immediate vicinity, suggest its function as a principle source of water for neighboring residents.

Figure 3.

Map of Group A at Medicinal Trail. The Medicinal Trail Reservoir (Operation 10) is shown in the upper right. Depressions A-1 and A-2 were investigated by Lowe (Reference Lowe2008). Contour interval is 15 cm. Adapted from Stowe and Hyde (Reference Stowe, Hyde and Valdez2014).

Numerous small aguadas or small reservoirs in the immediate area of household plots or house mounds throughout the lowlands have been noted (Bullard Reference Bullard1960; Matheny Reference Matheny1976; Scarborough Reference Scarborough, Scarborough and Isaac1993, Reference Scarborough1998). Bullard (Reference Bullard1960:364), in connection with his survey in the northeastern Peten, initially reported that “there is a marked tendency for these house ruins to occur in the vicinities of present-day, and possibly former, water sources…It is my impression that the maximum distance from a water source was probably less than two kilometers.” Scarborough (Reference Scarborough, Scarborough and Isaac1993) also points out the importance of households situating themselves as close to a water source as possible, highlighting the competitive aspects of neighboring households and a finite water supply. This spatial relationship between habitation structures and water features has recently been confirmed in the central lowlands at sites in proximity to Medicinal Trail, such as La Milpa, Dos Barbaras, and Wari Camp (Scarborough et al. Reference Scarborough, Becher, Baker, Harris and Valdez1995; Weiss-Krejci and Sabbas Reference Weiss-Krejci and Sabbas2002). The structures nearest the Medicinal Trail Reservoir fall well within this 2 km radius.

The primary goal of the Depression A-3 excavations was to clarify the role of this feature as a potential water resource and demonstrate its use history. A secondary goal was to gain a better general understanding of the role that household tanks played in the daily lives of ancient Maya people, particularly those within a decentralized or hinterland context outside of large urban centers. The earliest occupation evidence in the vicinity of the Medicinal Trail Reservoir dates to the Late Preclassic (400 b.c.–a.d. 100) and derives from house mound and courtyard excavations in Group A (Hyde Reference Hyde, Trachman and Valdez2009). Excavations began under the assumption that the reservoir would also have been in operation during this period.

The depression was excavated to sterile sascab (calcareous marl) and all recovered cultural material was assessed and catalogued by the project ceramicist and lithicist (Hyde Reference Hyde2007). Ceramic material was assigned a preliminary date (if possible) based on the chronologic ceramic typology being developed for Medicinal Trail. These data would prove useful in establishing a date range for the active lifespan of the feature, as well as potentially drawing a parallel between its use and the occupation of nearby residential complexes. Total reservoir capacity for Depression A-3 (and all other reservoirs investigated in this study), based on their combined current and maximum excavated depths, was estimated by taking the formula for an elliptical cone, H (1/3) × π (^A/₂) × (^B/₂), where H is the height and A and B are the length and width, respectively, and modifying it to accommodate the fact that smaller reservoirs tend to be more spherical in shape. The derived formula, H (1/2) × π (^A/₂) × (^B/₂), employs a constant (1/2) that is halfway between the constants of the formulas for a cone (1/3) and a hemisphere (2/3), and was used to calculate the volume of the reservoirs studied at Medicinal Trail and Yaxnohcah (Brewer Reference Brewer2007). The result was a volume of over 153 m³ (153,000 liters, or over 40,000 gallons), which would have provided over 80,000 person/day servings maximum (Table 1). McAnany's (Reference McAnany, Culbert and Rice1990) extremely conservative standard of 1.9 L (0.5 gallons, based on eight 8 oz servings per day) of water per person per day has been debated, with a more recent estimate of 17 L (4.5 gallons per person per day) applied to the site of Xculoc (Becquelin and Michelet Reference Becquelin and Michelet1994). This figure, based on a detailed survey of contemporary consumer groups occupying the village, is derived from a combination of individual daily consumption and a calculated supply of renewable (wells) and non-renewable dry season water reserves (cisterns and reservoirs). With generous allowances for laundry and additional non-potable uses this estimate is likely liberal, with the actual ancient Maya dry season water use probably falling somewhere in between. As a compromise, an estimate halfway between these two figures (9.5 L per person per day) was used to calculate the maximum person/day servings in order to project a localized support population for the Medicinal Trail tank as a source of potable water. A full reservoir, then, with no evaporation could provide over 43 people with enough drinking water each day for one year. This figure would undoubtedly be reduced when taking evaporation rates and additional agricultural and domestic water uses, such as cooking and washing, into account. Nonetheless, the reservoir would have served as a reliable water source for residents in this area of the community.

Table 1.

Data summary and evaluation of all reservoirs investigated by the author.

The presence of a degraded plaster floor located between a layer of clayey reservoir sediment and a lower, clay-rich (Ab) horizon atop sascab is another positive indicator that the depression functioned as a water storage feature. Though sometimes difficult to differentiate from in-washing clay sediment, the degraded remains of this floor were encountered in multiple units throughout the depression roughly 25–35 centimeters below the surface and interpreted in the field as the remains of a relatively impervious sealant (Figure 4). The limestone bedrock underlying the depression is highly permeable and either natural or artificial modification would have been necessary to retard leakage. Weiss-Krejci and Sabbas (Reference Weiss-Krejci and Sabbas2002) report the presence of a similar hard gray layer, between 10 and 30 centimeters thick, overlaying white, medium-hard, smooth bedrock at four excavated depressions near the neighboring Wari Camp and La Milpa East sites that they interpret as small water reservoirs. Similarly, the large, extensively excavated La Milpa Aguada was subjected to extensive quarrying and contained a huge berm or dam on the western side that created or enhanced its capacity. A small stone-lined well (bukte) that functioned to extract water from surrounding saturated clay, originally Late Classic before being reopened in the Terminal Classic/Early Postclassic, was also discovered within the bottom of the reservoir. Core samples collected from the base of the aguada revealed a kaolin clay lining of either natural or unnatural origin (Scarborough et al. Reference Scarborough, Becher, Baker, Harris and Valdez1995). Further evidence of the Maya practicing these simple, yet practical modifications has also been noted in multiple aguadas at Calakmul (Folan et al. Reference Folan, Marcus, Pincemin, Carrasco, Fletcher and Lopez1995), Uaxactún (Smith Reference Smith1950:61, Figure 99b), and near Dos Hombres (Trachman Reference Trachman2007). Within Depression A-3, a layer of in-washing clay sediment overlays the sascab base of the feature. Atop this, the highly degraded floor composed of compacted clay with sascab rubble intermixed lies beneath additional reservoir sediment and modern soil.

Figure 4.

South profile drawing of Operations 10Q, 10R, 10Y, and 10Z at the Medicinal Trail Reservoir, showing the remnants of a heavily weathered floor. Drawing by author.

Bedrock at the base of each excavation unit was examined for evidence of quarrying activities and the possible presence of a water-retention or otherwise culturally modified “wall” or a channel that would have permitted the flow of water into and out of the reservoir. Small depressions elsewhere in the Maya lowlands have been interpreted as rock quarries, sascaberas (sascab mines), and clay mines (Folan Reference Folan1982; Tourtellot and Rose Reference Tourtellot and Rose1993). The notion that small water tanks originating as natural depressions also served as quarries for building material before being modified to store water bears further examination and is also being considered in water management investigations elsewhere in the Maya lowlands (Weiss-Krejci and Sabbas Reference Weiss-Krejci and Sabbas2002; Brewer et al. Reference Brewer, Carr, Dunning, Walker, Hernández, Peuramaki-Brown and Reese-Taylor2017). Most of the bedrock within Depression A-3 appeared to be naturally decomposing and exhibited no conclusive evidence of quarrying, with the exception of visible cut marks and flattened edges on the limestone revealed at the base of Operation 10J. This discovery, combined with a lithic inventory consisting of multiple tools (n = 57), including at least one intact mid-sized biface, supports the notion that quarrying activities may well have been taking place within the depression at some time during its use history. Based in part on experimental archaeological research conducted at the site of Nakbe, a variety of stone tools composed of chert, including bifacial axes, picks, and hammer stones, have been demonstrated to be excellent tools for mining, cutting, and shaping limestone (Hansen Reference Hansen and Houston1998). The stone tools recovered from Depression A-3 were generally poor to very poor in quality and, with the exception of a single chalcedony scraper, composed entirely of chert. Biface tools comprise over half of the tool assemblage (n = 30), more than half of which are forms related to agriculture (oval bifaces and bifacial celts). Informal and expedient tools, including scrapers and utilized flakes, account for the remaining majority (n = 13) of the remaining tool assemblage. The overall lithic assemblage from the depression is best characterized as being dominated by low-quality chert material used to produce bifaces for local consumption, agriculture, and limestone quarrying (Hyde Reference Hyde2007).

Recovered ceramic material included a wide variety of rims and body sherds, basal flanges, and a single eroded vessel base with a broken mammiform foot. The majority of sherds from inside the depression, deriving from all operations except seven of the posthole units initiated around the perimeter of the feature, were eroded and only a portion could be stylistically dated. It is likely that the Maya employed ceramic materials in the course of utilizing the reservoir but most of this material is either too small, too heavily eroded, or has disintegrated entirely due to the continuous exposure to water and pressure. With the exception of a few rim forms and ring bases that belong to the Chicanel phase (Late Preclassic period, 350 b.c.–a.d. 250), the majority of recovered ceramic material dates between the Tzakol (Early Classic, a.d. 250–550) and Tepeu I/II (Late Classic, a.d. 550–850) complexes. This range of forms, phases, and dates correlates strongly to other ceramic artifacts recovered in the vicinity of the depression (Hyde Reference Hyde2011). Ceramics recovered from Group A clearly indicate an occupation from at least the Late Preclassic through the Terminal Classic, with a likely Middle Preclassic presence.

The analysis of recovered soil samples provides additional support for the depression functioning as a reservoir. In an attempt to reconstruct the types of vegetation immediately surrounding the depression through organic or botanical remains, a 1.5-L soil sample was collected from Operation 10C at a depth of 67 cm below the surface. The sample was floated for micro- and macro- plant remains using a Flote-Tech model A-1 machine in the anthropology lab at Northern Illinois University. After the samples were air dried, they were passed through a standard series of graduated sieves (4.0–0.425-mm mesh) for better viewing. Overall, the sample consisted of small limestone chunks and hard clays, with a number of small pieces of heavily eroded wood charcoal suspended in the matrix. A single palm seed fragment, tentatively identified as Arecaceae sp., was recovered. Palms were used and tended by the ancient Maya in and around settlements, and continue to be grown and harvested by their modern descendants (Darch Reference Darch, Turner and Harrison1983; Dunning and Beach Reference Dunning and Beach2003). In addition, a total of nine seeds determined to be from the Onagraceae family (possibly of the Oenothera genus) were identified from the sample (Figure 5). These are seeds from a plant currently being investigated as part of the evening primrose family, and samples have been recovered from several other sites in the PfB area, including Blue Creek, the Barba Group, and Guijarral (Hageman and Goldstein Reference Hageman and Goldstein2009). Although its exact significance or relationship to human activity in this time period is unclear, it has been found in conjunction with both domestic and feasting loci and its presence appears to be an indicator of human presence and activity (Goldstein and Brandt Reference Goldstein and Brandt2007; Goldstein and Hageman Reference Goldstein, Hageman, Staller and Carrasco2010).

Figure 5.

Image of Onagraceae seeds recovered from the Medicinal Trail Reservoir. Image from Goldstein and Brandt (Reference Goldstein and Brandt2007).

Ultimately, Depression A-3 was determined to have originated as a quarry before functioning as a domestic-scale reservoir based on a wealth of recovered physical and cultural data. The depression's surface area and calculated capacity, the presence of a degraded clay sealant overlaying the bedrock, and its association with a large formal household group all support its role as a water storage feature. Analysis of recovered ceramic material revealed that the reservoir was in use contemporaneously with occupation of the adjacent structures, lending further support for its importance to the community's inhabitants. Environmental indicators in the form of recovered palm seeds provide additional evidence of human activity around the depression.

Additional Household Water Management Infrastructure at Medicinal Trail

Initial excavations at Medicinal Trail consisted of two studies that investigated mounds (Ferries Reference Ferries2002) and terraces (Farnand Reference Farnand2002) that cross the main trail through the site. Prehistoric terraces are common features of Maya archaeological landscapes and have often been used to define agricultural production areas. These features do not invariably delineate arable land, however, and other uses, such as providing foundations for structures or managing the flow of water, have also been hypothesized. Terraces at Medicinal Trail were studied with the goal of understanding their formation processes and possible role in water management. Farnand determined that each of the terraces investigated were used for a unique purpose, including agricultural, structural, and possibly even territorial functions. Of the four alignments studied, one (Alignment 1) was determined to support a large terrace extending upslope into land that would be optimal for cultivation. A second terrace (Alignment 3) is believed to have served either as an agricultural terrace or a property boundary marker. Alignment 4 is a structural terrace directly joining another contour terrace upslope. The fourth terrace (Alignment 2), however, may well have served in a water management capacity. Like Alignment 1, it supports a large terrace that extends upslope. If subjected to higher erosional rates, however, it is possible that it would not have been able to sustain agricultural activity and may have instead aided in erosion prevention or water diversion (Farnand Reference Farnand2002). If so, this feature might have functioned as a check dam or weir terrace (Beach et al. Reference Beach, Luzzadder-Beach, Dunning, Hageman and Lohse2002; Dunning and Beach Reference Dunning and Beach1994), acting to restrict the flow of water and create land for cultivation, both reasonable assumptions for this agrarian community.

More recently, excavations seeking evidence of water management modifications (Lowe Reference Lowe2008) took place within two small depressions on the west side of Group A, roughly 15 meters west-northwest of the northern courtyard (Depression A-1) and 15 meters west of the middle courtyard (Depression A-2) of the group. After testing both depressions to determine their nature and function, Lowe concluded that neither feature served as a reservoir. Both were small and shallow, with total surface areas of 38 m² (Depression A-1) and 40 m² (Depression A-2) and catchment areas that were difficult to identify or assess. Both features also lacked a distinct clay or other seal that would have aided in water retention. Ultimately, Depression A-1 was determined to be an unmodified natural feature of the landscape, possibly the result of a tree fall, and Depression A-2 appears to be the result of a natural depression being modified and expanded into a small limestone quarry. Although Lowe dismissed Depression A-2 as a reservoir given the lack of physical or cultural evidence, if it did retain water in some capacity following quarrying activities, this small tank would have offered a convenient supplemental, probably non-potable, water source for the inhabitants of Group A.

Three studies associated with Group C have been conducted in attempts to identify additional structures and features and their potential role in water management activities in this area of the Medicinal Trail site (Dedrick Reference Dedrick, Trachman and Valdez2009; Gill Reference Gill, Trachman and Valdez2009; Percy Reference Percy, Trachman and Valdez2009). Group C is classified as a small Second Tier courtyard group and is located 50 m south of the Tapir Group. Households in Second Tier groups are characterized by two or three structures arranged around a semi-formal courtyard and lack eastern ceremonial structures (Brewer et al. Reference Brewer, Hyde, Stowe and Valdez2013). Group C consists of three courtyard groups dispersed around a series of landscape modifications, including terraces, berms, and depressions, likely related to agricultural activities (Figure 6). The topography surrounding the group is steep relative to the extensive, low-lying plain to the east, and a series of interconnected berms appear to function to direct water away from the larger Tapir Group household toward four reservoirs. The flat plain below Groups C and D contains multiple terraces and reservoirs that, if coordinated, would have collected rainwater from upslope and distributed into adjacent agricultural fields.

Figure 6.

Plan map of Group C at Medicinal Trail detailing Operations 14 and 15. Dashed lines show general contours and arrows indicate probable flow of water along berms toward the Operation 14 chultun and Operation 15 depression. Adapted from Hyde (Reference Hyde2011).

Operation 15 focused on determining the function of three landscape features posited to relate to water management activities: two berms and an associated depression (Gill Reference Gill, Trachman and Valdez2009). The relationship between water management features used to capture and redirect water for consumption and agriculture has been well documented throughout the Maya area and berms, in particular, have been found at a variety of nearby sites within the Rio Bravo Conservation Area including La Milpa and Guijarral (Dunning and Beach Reference Dunning and Beach2003; Hughbanks Reference Hughbanks, Adams and Valdez1995; Scarborough Reference Scarborough2003). The slope, alignment, and composition—limestone and chert construction cobbles ranging in size from 5–45 centimeters in diameter—of Feature 15-A present both internal and external features of a berm. The pitched, “roof-like” construction may have been used to divert water along its east and west margins (Gill Reference Gill, Trachman and Valdez2009). Similarly, Feature 15-B appears to have been used to slow and direct the flow of water downslope toward the southeastern depression. Ground survey of this depression revealed several cut marks in the limestone along its southern boundary and a large, poorly preserved limestone boulder was removed from its western half (Operation 15 F). Taken together, these findings suggest that the depression was quarried for construction material before serving in some capacity as a reservoir. Analysis of the ceramic material recovered in the Operation 15 excavations reveal a Late Classic construction and use of these features, which correlates with occupation dates documented for this area of the site (Dedrick Reference Dedrick, Trachman and Valdez2009; Gill Reference Gill, Trachman and Valdez2009).

At the north end of Group C is a semi-formal courtyard group of three mounds with a possible chultun and two depressions separated by a long berm to the east and southeast (Dedrick Reference Dedrick, Trachman and Valdez2009). At its southern end, this nearly 40-meter-long berm hooks to the east and appears to intersect with a small separate berm investigated as part of the Operation 15 excavations. The depression studied at Operation 15 is located southeast of this intersection and a ditch that appears to be a drainage feature begins at this feature and winds its way south to an additional depression (Brewer et al. Reference Brewer, Hyde, Stowe and Valdez2013). The primary objective of Operation 13 was to examine three structures that share a common basal platform, their immediate surroundings, and the role this segment of the community may have played in the economic activities of Medicinal Trail. In northwestern Belize, multiple hilltop-focused agricultural sites are composed of large, economically prosperous household groups surrounded by smaller household groups associated with visible agricultural features (Lohse Reference Lohse, Lohse and Valdez2004). The nature of these smaller households in the agricultural production of hilltop sites lacks in-depth study, and the similar configuration of Medicinal Trail offers an analogous dataset to consider. The water management component of the Operation 13 investigations was the series of excavations conducted at an apparent chultun within the center of Group C (Operation 14). Limited in scope, the primary purpose of this operation was to establish a basic soil stratigraphy and examine the bedrock morphology within the feature. Although no obvious modifications to the bedrock were observed, cultural material in the form of lithic flakes and ceramic sherds were collected. No dates were assigned to the ceramic material, and it is hypothesized that this depression functioned in tandem with the adjacent berms in order to collect, and possibly redistribute, water for agricultural purposes (Percy Reference Percy, Trachman and Valdez2009). As with other potential water management features surveyed and cursorily tested throughout the site, the hydrologic infrastructure associated with Group C requires additional excavation and analysis.

Wo’ Group Residential Reservoir (Operations 16B, 16C, and 16D)

The first reservoir tested was located 45 m southeast of the Wo’ Group residential complex then being investigated (Peuramaki-Brown et al. Reference Peuramaki-Brown, Morton, Castro, Hernández, Peuramaki-Brown and Reese-Taylor2018). Three excavations (16B, 16C, and 16D) were opened in this irregularly shaped, shallow depression resulting in a contiguous 1.5 × 1.5 m unit positioned on the eastern margin lip of the feature. The goal of these excavations was to investigate the possible presence of a water retention wall, channel, or other modification, targeting places with exposed limestone visible on the surface of the rim and with suggestive surrounding topography.

Based upon the exposed limestone at the base of the unit, which displays evidence of cut marks on several blocks, this depression appears to have initially functioned as a quarry for building material (Figure 9). If limestone blocks were being mined for construction in the immediate vicinity, their most likely destination would be the adjacent Wo’ Group. Indeed, initial comparative analyses of ceramic material from the depression and Operation 17 F at the structure group itself indicate contemporaneity in Early/Middle Preclassic forms (Walker Reference Walker, Hernández, Peuramaki-Brown and Reese-Taylor2018). This apparent temporal (and type) relationship between operations, combined with the accessibility of the depression's location, support the notion that the feature could well have functioned as a quarry for Preclassic period building material at the Wo’ Group. The lack of either a channel or other culturally modified feature in this area of the depression or evidence of a clay sealant call into question the notion that this feature served as a residential water tank. Its surface area, depth, and location bordering a residential complex in an area lacking any other visible water features, however, support the idea that this depression may have been utilized as an opportunistic water source, or “quarry reservoir,” perhaps for non-potable purposes. In addition, the catchment area bordering the south, west, and southeast sides of the depression would have been positioned to either receive outflow from or shed runoff into the reservoir, probably for agricultural purposes. Similar depressions originating as quarries before being modified and used as reservoirs have been identified elsewhere across the Maya lowlands (Folan Reference Folan1982; Weiss-Krejci and Sabbas Reference Weiss-Krejci and Sabbas2002).

Figure 9.

South profile of Operations 16B, 16C, and 16D, showing location of cut stones. Drawing by author.

Suburban Alba North Residential Reservoir (Operations 16E–16I and 16 K)

The second small depression was located 130 m northeast of Structure A-1 of the Alba Group, near a series of nearby house mounds that had not yet been excavated. Three separate operations were initiated across the center and along the north rim of the feature. Sascab exposed at the base of the depression was flat, smooth, and was overlaid by a thick layer of sediment (Figure 10). The depression likely originated as a quarry associated with the construction of the nearby massive Alba Group monumental architecture, before becoming partly filled with in-washing sediment (C3 and C4 horizons), sealed with a now highly degraded plaster floor (C2 horizon), and further filled by accumulating reservoir sediments (C1 and AC horizons). Although not representative of the type of well constructed and maintained watertight seals overlying the bedrock in the larger central precinct reservoirs found within many Maya urban centers, this plaster surface would, nonetheless, have served to greatly increase water retention within the reservoir. The profiles of Operations 16E and 16 F revealed a similar deposition of reservoir sediments, but evidence of this former floor was visible only in 16 F, located in the center of the depression.

Figure 10.

Operation 16 F west profile, showing remnants of a highly weathered plaster floor. Photograph by author.

Contiguous operations 16G, 16H, 16I, and 16 K, located on the north rim of the depression, presented another interesting aspect of the tank. Large rocks exposed throughout this unit appear to be the result of deliberate cultural activity, based on their placement above the C soil horizon and their alignment (Figure 11). In addition, the collapse of these stones also appears to have dislodged other unnaturally placed stones. The type and nature of the feature that these stones would have comprised remains unknown, although it is evident that some type of construction activity was taking place around the perimeter of the reservoir.

Figure 11.

Base of Operations 16G, 16H, 16I, and 16 K, showing large placed stones. Photograph by author.

Excavation findings combined with a high density of ceramic material (n = 610) and a proximate spatial association with the Alba Complex support the idea that this depression functioned as a reservoir. The reservoir's surface area and calculated volume combined with the topography of the surrounding landscape, which could have shed water downslope into the reservoir from a large catchment surrounding it on the west, south, and east sides, further support the feature's water storage capabilities. Although the neighboring residential groups have yet to be excavated, it is likely that ceramics recovered in the depression will coincide with dates associated with these structures, supporting the idea that the reservoir was in use concurrent with occupation in this area of the site.

Suburban Fidelia North Residential Reservoir (Operation 16J)

The only depression not located on the Alba-Fidelia transect, this small tank was located 130 m north of Structure F-1 of the Fidelia Complex. An L-shaped mound group is located immediately adjacent to the northern edge of the reservoir and the working hypothesis, based on its layout and recovered ceramic dates from nearby test excavations, was that this location was the likely setting for an Early Classic period farmstead. Another apparent reservoir that contains a possible sluice gate or dam feature is located 80 m to the south. Earlier investigations in this area included a 2 × 2 m excavation unit placed between these two depressions, from which DNA samples were recovered from soil containing both cotton and maize indicators (Anaya Hernández Reference Anaya Hernández, Reese-Taylor and Hernández2013). A water retention feature in the south depression could have served to allow and regulate the release of water into this field separating the two tanks, with the agricultural water runoff then funneling into the Suburban Fidelia North reservoir. This collected runoff could have then been recycled for non-potable uses, such as additional pot irrigation.

The current shallow profile of the small reservoir is the result of over one thousand years of sedimentation and soil formation following its use and abandonment. A series of exposed stones that appear to be aligned, possibly indicating the remains of a cultural feature, are located along the western margin of the depression, which also forms its highest present edge. Within the depression, evidence of a decomposing floor and superjacent reservoir sediments like those examined in the Suburban Alba North reservoir are visible in the profile (Figure 12). Nearly 150 centimeters below the surface, the C3 horizon consists of weathered remains of a floor constructed of hard-tamped clay mixed with sandy sascab, a technique still used today to line irrigation ditches and other hydrologic features in the Yucatán (Dunning et al. Reference Dunning, Weaver, Smyth, Zapata and Stanton2014). Above this surface, a thick layer of clayey reservoir sediments (C2 horizon) accumulated over time, with broken ceramics and other artifacts intermixed. Episodic seasonal desiccation of these sediments appears evident in the development of slickensides, a product of shrinking and swelling clay, which also caused distortion in the underlying floor. During the final years of its use, or post-abandonment, the depression then began to fill with colluvial sediment (C horizon) derived from the disintegration of the adjacent residential complex, out of which the modern soil developed over a millennium. Two small charcoal fragments were recovered from the southwest corner of the unit at a depth approximately 1.55 meters below the surface and submitted for ¹⁴C dating. This analysis returned a date of 1570 ± 30 with the calibrated age 415–560 cal a.d. (p = 0.95; calibrated at 2-sigma with the program INTCAL13 [Reimer et al. Reference Reimer, Bard, Bayliss, Beck, Blackwell, Ramsey, Buck, Cheng, Edwards, Friedrich, Grootes, Guilderson, Haflidason, Hajdas, Hatté, Heaton, Hoffmann, Hogg, Hughen, Kaiser, Kromer, Manning, Niu, Reimer, Richards, Scott, Southon, Staff, Turney and van der Plicht2013]), correlating strongly with the presence of Middle Classic ceramic material also present at this depth (Walker Reference Walker, Hernández, Peuramaki-Brown and Reese-Taylor2018). Similar to the Suburban Alba North reservoir, dates attached to recovered ceramics coincided with dates associated with the neighboring residential complex, indicating that this reservoir was in use during the occupation of this area of the site.

Figure 12.

Operation 16J north profile, showing location of colluvium deposits. Drawing by author.

This relatively small, but originally deep, depression appears to have functioned in a water management capacity based on multiple spatial, physical, and cultural characteristics. The position of the depression immediately adjacent to an agricultural field (with another probable reservoir located on the west side of the field) and a structure group; its depth combined with the presence of a weathered plaster floor and evidence of intermittent desiccation/rehydration cycles in the stratigraphy; and high densities of ceramic material (n = 208) throughout the unit suggestive of cultural activity all support the notion that this depression served as a household reservoir, possibly to collect water from, or distribute water to, the bordering agricultural field.

Yax-3 Hinterland Aguada (Operation 22A)

The fourth depression excavated at Yaxnohcah is located roughly 500 meters northeast of the Yax-3 group's center. The size (30 m north-south × 30 m east-west) and roughly circular shape of this feature resembles a natural karst sinkhole with a clay plug in its bottom (Nicholas Dunning, personal communication 2016). Unlike the other small tanks tested, this depression contained vegetation indicative of the presence of water for at least part of the year (Figure 13). Fairly dense stands of saw grass and sedges, including Cyperus and Rhynchospora species and the cattail Typha dominguensis, were documented. These species have been associated with seasonally inundated aguadas elsewhere in the Maya area, including the sites of Tikal (Dunning et al. Reference Dunning, Griffin, Jones, Terry, Larsen, Carr, Lentz, Dunning and Scarborough2015) and Pulltrouser Swamp (Darch Reference Darch, Turner and Harrison1983). The fact that the depression was currently completely dry is not surprising considering investigations took place in mid-May, near the end of the annual dry season. Its profile as an active aguada was further supported by the presence of modern artifacts noted around the perimeter, including a chiclero (gum tapper) boiling pot, multiple glass bottles, and a shoe, suggesting recent historical use of the feature. Two small metal fragments were collected 70 cm below the ground surface, also evident of recent activity. The nearest ancient structure to the aguada, located 30 m west, has not been investigated but falls well within an accessible radius to take advantage of this reservoir. Additional residential groups are located 100 m northeast and 125 m southwest.

Figure 13.

Pre-excavation image of the Yax-3 Hinterland Aguada. Photograph by the author.

The depression is oval-shaped and currently fairly shallow, due to continual sedimentation and soil formation. A rise or “rim” is evident along the south edge, increasing significantly from west to east around the aguada's perimeter. This rim is also visible, but less defined, on the north side of the feature. A single 1 × 1 m unit was placed in the center and excavations reached a total depth of nearly two meters below present ground surface. Although no surface water was present, massive surface cracks visible in the stratigraphic profile are indicative of recent soil dehydration. These cracks continue over 50 centimeters into the profile through an increasingly sticky and moist clay matrix. The modern soil is a vertisol exhibiting significant shrink-swell behavior and subsequent clay movement (argilliturbation) over time. Aguadas have proven to be important sources of paleoecological data, the sediments within them often deposited in standing water with anaerobic conditions leading to the preservation of pollen and other microfossils (Akpinar-Ferrand et al. Reference Akpinar-Ferrand, Dunning, Lentz and Jones2012; Beach et al. Reference Beach, Luzzadder-Beach, Flood, Houston, Garrison, Román, Bozarth, Doyle, Lentz, Dunning and Scarborough2015b). In an effort to identify ancient vegetation present in the localized area surrounding the aguada, 15 pollen samples were collected from the south wall of the unit at 10-cm intervals between depths of 20 and 150 cm below ground surface. Analysis of these samples is ongoing.

A total of 94 ceramic sherds were recovered, tentatively dated to the Classic period (Debra Walker, personal communication 2016). Although the density of ceramic material was relatively consistent throughout the majority of the excavation unit, no artifacts were encountered in the dense, sticky clay (approximately 20 centimeters deep) overlying the sascab base of the aguada. Combined with a lack of cultural material at this depth, the composition of this thick bajo clay suggests that it acts as a natural aid in water retention. A pronounced topographical depression represents a natural place to collect water and, as has been reported elsewhere in the Maya lowlands, aguadas may begin to collect water due to the natural consequences of sedimentation by clays (Beach et al. Reference Beach, Luzzadder-Beach, Flood, Houston, Garrison, Román, Bozarth, Doyle, Lentz, Dunning and Scarborough2015b; Dunning et al. Reference Dunning, Luzzadder-Beach, Beach, Jones, Scarborough and Culbert2002). Whether deliberately deposited or not, the clay lining within the Yax-3 hinterland aguada would have increased the reservoir's ability to store water and supplement ground and surface water, or provide water in dry periods. Although lacking evidence of a former floor or sealed surface, the present vegetation and significant surface cracks are indicative of a current water feature. Based on associated ceramic dates, this feature appears to have originated naturally and, after partially filling with in-washing clay reservoir sediments, served as a reservoir beginning in the Classic period. It is possible that the reservoir was in use earlier, with antecedent sediment and associated ceramics having been removed by later (Classic period) dredging. Many aguadas have stratigraphic disjunctions as a result of periodic ancient dredging (e.g., Dunning et al. Reference Dunning, Griffin, Jones, Terry, Larsen, Carr, Lentz, Dunning and Scarborough2015).

Yax-3 Group Reservoir (Operation 22C)

The final small water feature investigated to-date at Yaxnohcah is located within the Yax-3 residential group currently being investigated by YAP (Anaya Hernández et al. Reference Anaya Hernández, Peuramaki-Brown, Reese-Taylor, Hernández, Peuramaki-Brown and Reese-Taylor2018). Massive exposed limestone blocks visible around the feature's rim, particularly along its south and west boundaries, and the presence of multiple structures within 75 meters of the reservoir (including a large structure bordering its eastern edge) indicate that this depression likely originated as a quarry associated with the construction of this residential complex before being modified and used as a small reservoir. Unfortunately, excavation could not be carried to bedrock in this depression because of time constraints and safety concerns.

Excavation of the depression produced a wealth of cultural and physical data, including a significant density of ceramic material. This consisted of multiple shallow vessel rim sherds, including one large Polvero Black bowl rim fragment with slip still largely intact. The ceramic mix from this operation tentatively dates from the Late Preclassic to Late Classic periods (Debra Walker, personal communication 2016). A charcoal sample recovered from the south wall (125 cm below ground surface) returned the date 2270 ± 20 with the calibrated age 400–210 cal b.c. (p = 0.95; calibrated at 2-sigma with the program INTCAL13 [Reimer et al. Reference Reimer, Bard, Bayliss, Beck, Blackwell, Ramsey, Buck, Cheng, Edwards, Friedrich, Grootes, Guilderson, Haflidason, Hajdas, Hatté, Heaton, Hoffmann, Hogg, Hughen, Kaiser, Kromer, Manning, Niu, Reimer, Richards, Scott, Southon, Staff, Turney and van der Plicht2013]), lending further support for use of the reservoir during the Late Preclassic. The weathered remains of two distinct surfaces visible in the profile represent multiple periods of use and refurbishment of the reservoir that appears to coincide with this range of ceramic dates (Figure 14). Atop a layer of in-washed sediment, the 5C horizon consists of a now highly weathered plaster floor beneath a thick, dark layer of reservoir sediments accumulated along with cultural material (4C horizon). These sediments also contained manganese and iron oxide concretions, indicative of the presence of abundant soil water at this depth of the depression. Above this is a degraded floor composed of a mixture of very dark, hard-tamped clay and sandy sascab similar to the former surface uncovered in Operation 16J. Another layer of reservoir sediments (2C horizon) and colluvium sediment resulting from the disintegration of the adjacent residential complex are located beneath the well-developed modern soil.

Figure 14.

North profile of the Yax-3 Group Reservoir, showing evidence of multiple highly weathered floors.

Taken together, the physical and cultural data recovered from this operation indicate that the depression likely originated as a limestone quarry during the Late Preclassic, or perhaps earlier. After subsequently filling with a layer of in-washing sediment, the tank was sealed with a plaster floor for use as a reservoir during this period. Following the accumulation of additional reservoir sediments, perhaps indicating a period of disuse or abandonment in this area of the site, the tank was again sealed with a clay-and-sascab surface to improve its water retention. The presence of a similarly constructed floor in the Operation 16J tank north of Fidelia—also dating to the Classic period—suggests this technique was employed as a low-cost (relative to plaster) solution for seasonal water storage throughout Yaxnohcah during this time.