Density, Area, and Volume As Complementary Tools to Understand Maya Settlement an Analysis of Lidar Data Along

Journal of Archaeological Science: Reports 29 (2020) 102178

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‘Structure’ density, area, and volume as complementary tools to understand Maya Settlement: An analysis of lidar data along the great road between T Coba and Yaxuna ⁎ Travis W. Stantona, , Traci Ardrenb, Nicolas C. Barthc, Juan C. Fernandez-Diazd, Patrick Rohrera, Dominique Meyere, Stephanie J. Millera, Aline Magnonif, Manuel Pérezg a Department of Anthropology, University of California Riverside, 900 University Ave., Riverside, CA 92521, USA b Department of Anthropology, University of Miami, 900 University Ave., Riverside, CA 92521, USA c Department of Earth Sciences, University of California Riverside, 900 University Ave., Riverside, CA 92521, USA d NCALM, University of Houston, 5000 Gulf Freeway, Houston, TX 77204-5059, USA e CHEI, 2109 Atkinson Hall, University of California San Diego, La Jolla, CA 92093-0436, USA f Cultural Heritage and Archaeology in the Maya Area, 4005 Hampden St., Kensington, MD 20895, USA g Instituto Nacional de Antropología e Historia, Av. Revolución 1900, Tizapán San Ángel, San Ángel, Ciudad de México, CDMX, CP 01000, Mexico

ARTICLE INFO ABSTRACT

Keywords: In this paper we present an analysis of lidar data along Sacbe 1, the longest causeway in Mesoamerica, con- Maya necting the sites of Coba and Yaxuna. In addition to performing an analysis of the density of polygons (utilized as Lidar a proxy for structures), we calculate the density of basal area and construction volume of the raised features seen Causeways in the data set. The results indicate that Maya sites in this region were fairly discrete and that the causeway was Yaxuna built to incorporate previously existing settlements dating prior to the period 600–700 CE. Further, the causeway Coba was an attractor of settlement in the area of state expansion.

1. Introduction defining visible architectural features drawn as overlays on bare-earth topography model visualizations. In this paper we present an alter- Since its first application in the tropical lowlands of the Maya area native method whereby the area and volume of contiguous archi- (Chase et al., 2010, 2011, 2012, 2013), lidar has quickly transformed tectural features visible in the lidar data are calculated and compared settlement archaeology and is now an essential tool utilized by an ever (see also Chase 2017; Schmidt et al., 2018). We perform our analysis on increasing number of projects (Brewer et al., 2017; Canuto et al., 2018; a lidar dataset that unites the sites of Coba, Quintana Roo and Yaxuna, Chase et al., 2014; Hare et al., 2014; Hutson et al., 2016; Inomata et al., Yucatan in the northern Maya lowlands of Mexico. These cities were 2017; Magnoni et al., 2016; Prufer et al., 2015; Rosenswig et al., 2013). connected by an approximately 100 km long causeway during the 7th Rather than a replacement for ground survey, it is clear that this century CE when the city of Coba appears to have experienced a period technology serves as a powerful complement to traditional techniques of extensive state expansion (Stanton et al., in press). utilized by archaeologists for nearly a century (see Ford and Horn 2018; Hutson et al., 2016; Magnoni et al., 2016; Prufer et al., 2015). Ground 2. Previous research and lidar data collection survey, however, will take a long time to catch up to the vast amounts of lidar data being gathered in recent years. In lieu of efforts to ground- The great causeway connecting the cities of Coba and Yaxuna, validate high quality surface models in areas where previous mapping known as Sacbe 1 (sacbe meaning white [sac] road [be] in Yukatec data do not exist, researchers have spent long hours digitizing visible Maya), caught the attention of the first archaeologists to perform sys- features, attempting to make sense of complex spatial patterning that, tematic research in the Maya lowlands (see Bennett, 1930; Thompson for the most part, lack chronological data. To date, this work has pri- et al., 1932; Villa Rojas, 1934). When this feature was first reported, the marily focused on calculating the number and density of polygons researchers of the Carnegie Institution of Washington (CIW) project at

⁎ Corresponding author. E-mail addresses: [email protected] (T.W. Stanton), [email protected] (T. Ardren), [email protected] (N.C. Barth), [email protected] (J.C. Fernandez-Diaz), [email protected] (P. Rohrer), [email protected] (D. Meyer), [email protected] (S.J. Miller). https://doi.org/10.1016/j.jasrep.2019.102178 Received 15 October 2019; Received in revised form 16 December 2019; Accepted 16 December 2019 Available online 31 December 2019 2352-409X/ © 2019 Elsevier Ltd. All rights reserved. T.W. Stanton, et al. Journal of Archaeological Science: Reports 29 (2020) 102178

Fig. 1. Area of the lidar surveys covered in 2014 and 2017.

Fig. 2. Villa’s (1934) map of Sacbé 1 (redrawn by Tatiana González).

Chichen Itza believed that the causeway connected that site with Coba, causeway system (Cortés de Brasdefer, 1981, 1984a, 1984b, 1984c; a large urban center located farther east towards the Caribbean (Fig. 1). Folan et al., 1983, 2009; Folan and Stuart, 1974, 1977; Gallareta However, after traversing the feature it was apparent that Yaxuna, a Negrón, 1981, 1984; Garduño Argueta, 1979). While the extensive and much smaller, but earlier site than Chichen Itza was the western ter- detailed maps of the domestic zones of the ancient city are well known, minus (Fig. 2). Despite the cursory survey by the CIW archaeologists this groundbreaking work had to contend with the arduous task of (Thompson et al., 1932; Villa Rojas, 1934) no systematic work was ground survey and transit mapping in a tropical forest environment, performed in association with Sacbe 1 until the Instituto Nacional de mitigating the amount of area that could be covered. While the cau- Antropología e Historia (INAH) project commenced at Coba in 1970s. seways present at the site, including the easternmost 4.5 km of Sacbe 1, The Classic period city of Coba is the largest known Prehispanic were mapped by the project, there was no eﬀort to problematize this settlement in the northern lowlands of Quintana Roo, and is among the causeway as a speciﬁc focus of research (see Benavides, 1976, 1981). greatest cities of the Maya world (Navarrete et al., 1979; Thompson The next work related to Sacbe 1 was undertaken on the opposite et al., 1932); for comparison, while detailed comparisons of Maya end of the causeway when David Freidel directed research at Yaxuna urban centers are more complicated and need to take chronology and during the 1980s and 1990s. Much like the work at Coba, Freidel’s structure density into account, Chunchucmil, a contemporaneous city project (Selz Foundation Yaxuna Project) mapped a relatively short on the western side of the northern lowlands had an area of only 25 km2 segment (400 m) of the causeway and other associated architectural for its urban core, with 64 km2 calculated for a broader zone including features within the boundaries of the site (Stanton et al., 2010). In the suburbs and surrounding hamlets, but some integrated areas in the case of Yaxuna, however, excavations were conducted within the cau- south such as Caracol, Belize measure up to 200 km2 (Chase et al., seway and at the terminus building (Ardren, 2003). These excavations 2010, 2013; Hutson, 2010; Magnoni et al., 2012). Sprawling across suggested that the causeway was constructed and used during the approximately 63 km2, this urban center has very large monumental Yulum ceramic complex (equivalent to the Palmas ceramic complex at constructions and numerous carved monuments depicting bellicose Coba [see Robles Castellanos, 1990]), approximately 550–700 CE, rulers standing over bound captives. On some of these monuments placing it during the period of Coba’s apex (see Johnstone, 2001; Loya (dating to the period of the construction of Sacbe 1) the kaloomte’ title González, 2008; Loya González and Stanton, 2013, 2014; Robles (reserved for the highest rank of Maya royalty) was utilized (Esparza Castellanos, 1990; Shaw and Johnstone, 2001; Stanton and Freidel, Olguín, 2016; Guenter, 2014). Serving as a pioneering example of set- 2005; Stanton et al., in press; Suhler et al., 1998; Tiesler et al., 2017). tlement pattern archaeology in the Maya lowlands, mapping work at During this same period Yaxuna appears to have diminished in its po- the site during the 1970s covered what we estimate to be around litical importance and several researchers have suggested that it was 55–60% of the denser settlement articulating with the internal integrated into a state formation centered on Coba (Stanton and Freidel,

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located block that included the majority of Chichen Itza, and two one kilometer wide transects. One of these transects connected the survey blocks around Chichen Itza and Yaxuna while the other was a rather short transect along the first four kilometers of Sacbe 1 towards Coba (Magnoni et al., 2016). These data were collected with an Optech Ge- mini, which can record up to four discrete returns per laser shot (first, second, third, and last), from 500 m above the ground level and at a nominal ground speed of 65 m/s. The scanner was operated at ± 14 degrees and 45 Hz, generating a swath width of 250 m with the swaths of adjacent lines overlaping by 50% laterally. The system range resolution is about three meters, which implies that the sensor will not be able to detect distinct returns from objects that are separated by less than this distance along the trajectory of the laser pulse (such as returns coming from the top of short vegetation and the ground). The sensor was configured with a pulse repetition frequency (PRF) of 125 kHz and a beam divergence of 0.8 milliradians, which yielded a laser footprint diameter of 0.4 m from the nominal flight altitude. The combination of all of these parameters yields a nominal laser pulse density of 15 pulse/ m2, which, if distributed uniformly, would yield an 18% surface illumination. In 2014 rainfall was unusually high and there was much more vegetation than during the later 2017 survey. Our 2014 data collection was characterized by a problematic vegetative noise of about one meter height for a lidar survey at Yaxuna (Magnoni et al., 2016). At around the time this first lidar survey was undertaken the project began to focus on the relationship Yaxuna had with Coba during the 7th century CE. The Proyecto Sacbe Yaxuna-Coba (PSYC), under which our work at Coba has been conducted, is an offshoot of our broader efforts to understand longstanding questions of social, political, and economic integration from the view of households in the northern Maya lowlands. We use the term integration to frame ideas about the structure, degree, and kind of social interactions among members of a population. Understanding the complexities of how people structured their social interactions (e.g., hierarchical vs. heterarchical, kinship vs. state orga- nizations), the degree to which those interactions fostered a sense of integration (closely integrated vs. loosely integrated), and the kinds of interactions they developed, maintained, and dissolved (e.g., economic, ritual, political), informs us tremendously about how ancient societies self-perpetuated and helps us to create more nuanced narratives of the past. Bundling these three concepts under the rubric of integration provides a lens to look at archaeological data in a more inclusive fashion that acknowledges the intersectional nature of social relations. Within this research framework, Stanton and Ardren initiated work (still ongoing) which focused on the excavation and comparison of households at Coba, Yaxuna, and one intermediate site along the causeway. Part of the research design of PSYC included expanding the lidar Fig. 3. Hillshade images of central Yaxuná DEM; top (2017), bottom (2014). survey to include a one kilometer wide transect of Sacbe 1 in its entirety as well as a block survey around Coba. Unfortunately, as is apparent in 2005; Tiesler et al., 2017). Yet despite the dating of the causeway, very the data, the survey design missed approximately 30 km of Sacbe 1. The little was known about the economic, political, and social dynamics causeway is much more erratic in orientation than previous surveys and along the causeway around the 7th century CE and none of the settle- remote sensing (Google Maps) suggested, appearing to veer off to sites ment between Coba and Yaxuna had been well-documented. that existed prior to its construction and off the flight plan (Rohrer and In 2007, the Proyecto de Interacción del Centro de Yucatán (PIPCY) Stanton, 2019). Given our broader question concerning Coba as well as reinitiated work at Yaxuna, specifically in the area of Sacbe 1, ex- other research interests the 2017 lidar survey also included some other tending the map nearly 3.5 km further to the east to the peripheral site areas; in particular several one kilometer wide transects (e.g., Coba-Ixil, of Tzacauil using a total station (Hutson et al., 2012; Stanton et al., Coba-Xelhá), some smaller block surveys around sites nearer to Yaxuna 2008). However, most of the work at the site since 2008 focused on and on the Island of Cozumel (in conjunction with the researchers understanding events centuries earlier (e.g., Collins, 2018; Fisher, working on the island), and some expansion of the lidar survey areas 2 2019; Stanton, 2017; Stanton and Collins, 2017) or later (Magnoni around both Yaxuna and Chichen Itza. In total 394.6 km of lidar were et al., 2014; Stanton et al., in press) than the period of the construction flown in 2017, but the environmental conditions and equipment per- and use of Sacbe 1. In 2014 PIPCY had the opportunity to fly a rela- formance were notably different from the 2014 lidar survey, influen- tively small lidar survey. In collaboration with the nearby INAH project cing the fidelity of data (see Fernandez-Diaz et al., 2014, 2016). In at Chichen Itza directed by José Osorio León and his colleagues, the contrast to the very wet conditions during 2014, rainfall was exceed- National Center for Airborne Laser Mapping (NCALM) flew 66.8 km2 of ingly low in 2017 and by the time the lidar survey was initiated there lidar (Fig. 1). This area covered the entire site of Yaxuna, a centrally had been several wildfires across the survey area, including Yaxuna (Stanton et al., n.d). These conditions considerably reduced the

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Fig. 4. Structure count (polygons) density across the study area. vegetative noise (on the average of 20–30 cm in 2017) and increased Optech Titan MW, which are documented to be considerable, including the fidelity of the bare earth models. The lidar data were also collected a range resolution of nearly 1.5 m or about of half of its predecessor the using different equipment in 2017, in this case using a Teledyne-Optech Gemini and larger surface illumination (Fernandez-Diaz et al., 2016). Titan MW which is newer generation multispectral, multichannel and Regardless, what is clear is that the 2017 flight collected much more multilook airborne lidar which operates at three laser wavelengths detailed ground data. Platform edges and smaller features, such as al- (1550 nm, 1064 nm, and 532 nm) (Fernandez-Diaz et al., 2016). The barrada walls, are much more visible in the second survey data. nominal flying height and ground speed were 550 m AGL and 70 m/s. fi The instrument was con gured with a scan angle and frequency of ± 3. Analysis of the lidar data 27 degrees and 29 Hz with a total laser repetition frequency of 525 kHz (175 kHz per channel). The combination of the above parameters yields 2 Analysis of the lidar data is still ongoing, and includes several a planned laser pulse density of 25 pulses/m and a swath width of phases. First, a program to ground-validate the data (potential ar- fl 560 m, which were own with a 50% overlap between adjacent swaths. chaeological features) is underway by teams of mappers using lidar ff The laser beam footprints of the di erent channels range between 16.5 products on globally positioned tablets; to date ground validation ef- and 55 cm in diameter, the combined unique surface illumination (not forts have been conducted at Coba, Yaxuna, Oxkindzonot, and Ekal, the including adjacent footprint overlap) is in excess of 200%. latter two sites located along Sacbe 1. These ground validated areas In order to gauge the difference in the fidelity of the lidar surface represent less than 1% of the total lidar survey, but give us a much fl models between the 2014 and 2017 ights, a small area of overlap was better understanding of how certain features are represented in the collected in central Yaxuna and along the westernmost four kilometers surface models, as well as how ground topography and vegetation im- ff of Sacbe 1 (Fig. 3). Given the substantial di erence in vegetative con- pact certain parts of the survey area (cf. Cap et al., 2018:46; Hutson ditions, however, it is difficult to assess how much of the improvement 2015; Hutson et al., 2016; Magnoni et al., 2016; Prufer et al., 2015). in the surface models is due to the technical advances of the Teledyne- Detailed maps of architectural and other features (small aguadas,

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Fig. 5. Structure basal area density across the study area. metates, etc.) visible on the surface are drawn on top of printed images edges of features that show more tell-tale indicators of elevated archi- of lidar at 1:40 scale; these are then digitized and georeferenced in the tectural construction such as sharp corners that may indicate platforms; laboratory. Some of this ground-validating overlaps with previously we did not include structures that were recorded through previous mapped areas of the settlement. Maps created by earlier projects, in mapping, but are not clearly visible in the lidar data as we are still in particular those published by Garduño Argueta (1979) and Folan and the process of digitizing earlier maps. Plazas/patios enclosed by visible his colleagues (1983) at Coba and the Selz Foundation map at Yaxuna structures on at least three sides are included within the area of the (Shaw 1998; Stanton 2000; Suhler et al., 1998) are in the process of polygons, but not those with only two sides enclosed unless the plaza/ being digitized and georeferenced over the lidar; visualized as the DEM patio is on a clearly raised platform. Other features such as causeways with the hillshade overlaid at 50% transparency. In areas where we have and visible albarradas (linear wall features) have also been digitized as not had the opportunity to ground-validate, these maps give us im- polylines along their centers. Facilitating this work in some areas of the portant spatial data based on the observations of researchers who survey is the fact that some of the terrain, especially in the eastern area documented spatial features on the ground in the 1970s and 1980s. The around Coba, is characterized by fewer limestone hummocks which combination of conventional maps with lidar data provides a greater presented issues when identifying features at Yaxuna in 2014 (Magnoni sense of how many architectural features may actually be present in et al., 2016). areas where no ground survey has been performed. It is important to stress, however, that we have only drawn polygons Finally, we have completed the preliminary identiﬁcation of archi- around features that appear to be elevated such as platforms and pyr- tectural features visible in the lidar in areas that have yet to be surveyed amids. There are many features in the lidar dataset, such as single on the ground. Guided by our previous work identifying structures in course walls composed of boulders that are not located on elevated the lidar of central Yucatan (Magnoni et al., 2016), we have drawn structures, but are clearly visible in the data. Some of these features polygonal shapes (which we use as a proxy for ‘structures’ here, al- represent ancient property walls (cf. Fletcher, 1978, 1983), and others though in practice most of these polygons include several features that are clearly the remains of foundation braces for pole and thatch con- would be considered structures on plan maps, see below) around the structions. While these features are being digitized as polylines, we will

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Fig. 6. Structure volume density across the study area. not include them in this analysis as we are continuing to work through one small ancillary building in a domestic group. Therefore, we have these data. Finally, the reader should keep in mind that the analysis decided to analyze the data not only in terms of number density of the presented here is based on our current draft of digitized features. As we ‘structures’, or better termed polygons (Fig. 4), but in terms of the basal move forward with different methods to visualize data we may refine area (Fig. 5) and built volume (Fig. 6) of construction as well, all of the features as some details may become clearer. which may have very different implications for understanding settle- In terms of the GIS analysis of the data, we focused on two primary ment patterns, but all three are metrics that can be easily calculated variables in addition to ‘structure’ count (polygon) density; volume and from polygons drawn around the external extents of contiguous archi- basal area of construction. Many projects have made calculations based tectural features if high resolution topography is available; importantly, on the density of structure counts (e.g., Canuto et al., 2018; Garrison we left the causeways out of the settlement analysis and calculated their et al., 2019; Inomata et al., 2018). However, we see several issues with area and volume separately. Moreover, we feel that the calculations this approach. First, currently there is no clear method for defining based on volume and area have the potential to be more easily com- what constitutes a structure for the kind of analysis we perform here. parable to other datasets based on structure density given the issues Does every mound or visible foundation brace need to be counted as a mentioned above. separate structure with a corresponding polygon? Do we group all All analyses were done using ArcGIS 10 Desktop software. The basal structures that share a common basal platform together as one struc- area of ‘structures’ was calculated for the polygons using standard ture? If not, do we count the basal platform as a separate structure? For ArcGIS tools for area (Calculate Geometry tool under the shapefile’s analyses of structure densities to be comparable among projects, these attribute table). The 8,130 polygons in the lidar dataset presented here kinds of questions need to be resolved and a standard methodology have a total area of 3,361,028 m2 with a mean area of 413 m2. The employed for digitizing features. Second, regardless of how the field minimum area of a polygon was 8.5 m2 and the maximum eventually standardizes the digitization of structures, we cannot find was 94,823 m2 for a monumental group. ourselves in the position that one large pyramid “counts” the same as A multi-step process was necessary to determine volumes of

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Fig. 7. Distribution of polygons across the study area.

‘structures’ utilizing our inventory of ‘structures’ as polygons and the where every pixel is a measure of the structure’s volume contained lidar bare-earth DEM as inputs. First, we used the Zonal Statistics tool to within the column above that pixel in m3 (a “m3 per pixel raster”). The extract the minimum elevation value (MIN operator) from the bare- Zonal Statistics tool was used to sum the raster values within each earth lidar DEM within each polygon and to create a new raster with ‘structure’ (SUM operator), which provides the ‘structure’ volume in m3; the minimum elevation value assigned to every pixel within each this all assumes, of course, that the construction is not built over some polygon (a “foundations only raster”). Essentially this method creates a natural rise, such as a hummock, and that the polygon trace is accurate flat base assumed to be the foundation of the ‘structure’. This method (result is a “m3 per structure raster”). Data contained in this raster can works well in this region of low slopes, but for regions with structures then be added (Append tool) to the original structure shapefile. For ease built on sloping terrain interpolating elevations into the foundation is of further spatial analyses, the polygons were converted to points (one likely a better approach (cf. methodology of Chase 2017). The point per ‘structure’ averaged on the polygon’s centroid with area and minimum elevation structure DEM was then merged with the true bare- volume data imprinted). earth DEM (Mosaic to New Raster tool), giving priority to the minimum Other operators and tools can be utilized to achieve the same result. elevations at the locations of the structures (this created a synthetic The Mosaic to New Raster step is not essential for the calculation but DEM with minimum elevation flat platforms within every structure, a helps to confirm that DEM differencing is correctly handled. Our “DEM with foundations raster”). By then subtracting the minimum workflow solely utilizes existing ArcGIS tools and functions but we note elevation structure DEM from the true DEM (Minus tool), we created a that a similar procedure could be adapted into open source GIS software new raster with pixel values giving the vertical distance between the (e.g. QGIS, GRASS). The 8,130 structures have a total volume top of the ‘structure’ and its assumed platform elevation (a “structure of 7,278,673 m3 (equivalent to approximately 2,900 Olympic swim- height raster”; outside of the ‘structures’ the raster values subtract to ming pools) with a mean volume of 895 m3. The minimum volume of zero). Because we were interested in determining volume in m3 we then one contiguous construction enclosed by a polygon was 4.2 m3 and the needed to multiply values in this raster by 0.25 (0.5 times 0.5 for the maximum was 715,212 m3. Point quantity (#) or structure-count, area size of our DEM’s pixels using the Times tool) to create a new raster, (m2), and volume (m3) were then analyzed in terms of density per

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The first cluster to the west of Ekal might be part of the site of Sacal, although Villa places the site a bit further to the west. Accounting for these clusters, the largest distance between sites along the causeway visible in the lidar is about 8 km; a distance easily walked in under a day. These data would suggest that travelers along this causeway would have had an ample number of places to rest and obtain food and water. Interestingly, the areas between sites are relatively devoid of architecture large enough to see in the lidar, suggesting that there was a fairly strict distinction between town and forest among the Prehispanic Maya (cf., Stanton et al., n.d.; Taube 2003). We also note that while there is some architecture outside of the larger clusters, it is quite possible that some of this isolated architecture may be from other periods. For example, around Yaxuna we have noted that Postclassic sites tend to be very small and dispersed (Stanton et al., in press). While Fig. 7 provides a way to visualize how architecture identifi- able in the lidar is spatially distributed, it does not capture the density of construction. In Fig. 4 we can see how the polygons used for visualization in Fig. 7 translate to a point density analysis. Each polygon was converted into a point (located at the center of the polygon) and, as mentioned in the previous section, visualized as a structure density per km2 using the Point Density tool with a 300 m search radius onto 50 m Fig. 8. Distribution of polygons in central Oxkindzonot (note that polygons pixels. As might be expected, the highly visible clusters of architecture represent the interpreted basal area of each structure). seen in Fig. 7 have similar patterns as the areas of highest point density in Fig. 6. The sites with the most substantial public architecture (Coba and Yaxuna) have the highest values for point structure-count density km2 using the Point Density tool with a 300 m search radius onto 50 m indicating an expected correlation between monumental architecture pixels (Figs. 4–6). and numbers of contiguous archaeological features; in general site centers have larger contiguous features than their peripheries. The 4. Results larger sites along Sacbe 1 also extend further, although it must be noted that the continuous values around these sites is the result of the 300 m Beginning with Fig. 7 we can appreciate the distribution of digitized search radius onto 50 m pixels method we selected. We found these structure polygons (here representing causeways and architectural values to give us the best visualization as the architectural clusters features) across the dataset. The black areas are the polygons drawn stood out more upon visual inspection, but changing them will alter around the contiguous architecture visible in the lidar. Many of the how the data look. There are also some areas that were not so apparent clusters visible in this figure are previously registered sites; those along in Fig. 7 that show up more in Fig. 4. For example, there are some Sacbe 1 were all originally reported by Villa (1934) in his ground- spikes between the sites of Kauan and Tuzil Chen in the point density breaking reconnaissance. As mentioned earlier, there are several in- analysis (Fig. 4) that are not so apparent in Fig. 7. Thus, the point stances in which the lidar veers off of Sacbe 1. In each of these cases density analysis is a way to draw out sites with larger amounts of ar- there is a Prehispanic site reported by Villa; we have placed the site chitecture with small horizontal footprints. names with question marks on Fig. 7 in the approximate areas Villa As we might expect, the area density analysis (Fig. 5) is in some fl places them on his map (see Fig. 2). As is readily apparent, most of the ways a re ection of the visualization of the areal extent of the polygons architecture near Sacbe 1 visible in the lidar dataset already corre- in Fig. 7. Unsurprisingly, Coba and Yaxuna, the two sites with the most fi sponds to a registered site. Some scatters of architecture between Hay monumental architecture, have the largest values. Yet in this gure we Dzonot and Tuzil Chen which might be grouped into two clusters (one see some spikes in secondary sites with substantial public architecture, between 2 and 4 km and the other from 7 and 10 km west of Hay in particular Ekal, Kauan, and Oxkindzonot, which were not as visible Dzonot) as well as a cluster approximately 3.5 km to the east of Ekal. in the point density analysis. Large temple complexes and enclosed,

Fig. 9. A comparison of the density of area, volume, and structure count (polygons) in central Yaxuná.

8 T.W. Stanton, et al. Journal of Archaeological Science: Reports 29 (2020) 102178 often raised, public plazas definitely impact this analysis. The site of CRediT authorship contribution statement Oxkindzonot (Fig. 8) is a good example of this, whereby a large public space has a significant impact on the area values (Fig. 5). As noted Travis W. Stanton: Conceptualization, Formal analysis, Funding elsewhere (Stanton et al., n.d.), the high values for area match well with acquisition, Investigation, Project administration, Methodology, the causeways at Coba. In one sense, this pattern relates to the sig- Visualization, Writing - original draft. Traci Ardren: Funding acquisi- nificant drop-off in values passing the termini of the internal site cau- tion, Investigation, Project administration, Methodology, Writing - seways; suggesting to us that the causeways represent a cultural original draft. Nicolas C. Barth: Data curation, Formal analysis, boundary enclosing the site settlement. In another sense, we can note Investigation, Methodology, Visualization, Writing - original draft. that the settlement around Coba gets drawn farther away from the site Juan C. Fernandez-Diaz: Data curation, Formal analysis, core along the two intersite causeways, Sacbe 1 to Yaxuna and Sacbe 16 Investigation, Methodology, Resources, Visualization, Writing - original to Ixil, indicating that intercommunity routes attracted settlement close draft. Patrick Rohrer: Investigation, Writing - review & editing. to Coba itself, likely due to economic reasons and easier access to roads. Dominique Meyer: Data curation, Investigation, Methodology, Finally, the volume analysis (Fig. 6) patterns fairly similarly with Resources. Stephanie J. Miller: Investigation. Aline Magnoni: the area analysis (Fig. 5). In general, high value areas marking sites are Investigation, Writing - review & editing. Manuel Pérez: Investigation. the same in both figures. This makes sense, especially for the sites with monumental architecture as monumentality implies a substantial in- Acknowledgements vestment in voluminous buildings. At a more microscale, however, the area and volume analyses do differ in some important instances. At We thank the Consejo de Arqueología of the Instituto Nacional de Yaxuna, for example, we can see that the larger values for area and Antropología e Historia for granting the permits to conduct this re- volume are somewhat different with the higher values for volume being search; all data are cultural patrimony of Mexico. This research was more restricted around the monumental architecture than the higher generously supported by the National Science Foundation (#1623603), values for area, which is drawn out away from the site core by less Jerry Murdock, Fundación Roberto Hernández, and Selz Foundation. voluminous, but aerially substantial (low, but broad) domestic archi- We also appreciate the support and guidance of María José Con Uribe, tecture (Fig. 9). These differences are not so much appreciated at the José Manuel Ochoa Rodríguez, and Fernando Robles Castellanos in our macroscale (Figs. 5 and 6), but we can clearly see those differences efforts to work at Coba, as well as two anonymous reviewers whose when comparing them at the site scale. Even more substantial, are the insightful comments helped us rethink some aspects of the research. differences between the values of area/volume and the density of David Asplund, Natalie Vasquez, and Diego Villarreal assisted in digi- polygons. The highest values for the point density shift much more to tizing the polygons. Finally, we thank the communities of Coba, Nuevo the west; away from the monumental architecture where the high va- Xcan, San Juan, San Pedro, and Yaxunah for allowing us to conduct lues for area and volume are located. The reason for this is that there research in their ejidos, as well as the landowners of the ranch at Ekal. are substantial clusters of smaller residential architecture to the west of the monumental core of the site. Many of the house structures in this References area of the site are not arranged around patios and are counted in- dividually, thus increasing the count density values for the polygons in Ardren, T., 2003. Memoria e historia arquitectónica en la estructura 6E-13 de Yaxuna. this area. Thus, in part these high values are a function of the fact that Temas Antropológicos 25 (1,2), 129–145. Benavides Castillo, A. 1976. El sistema prehispánico de comunicaciones terrestres en la this area is a residential area. We must point out that how researchers región de Cobá, Quintana Roo, y sus implicaciones sociales. Unpublished choose to draw enclosing polygons will greatly impact these values. We Licenciatura thesis, Maestro en Ciencias Antropológicas en la Especialidad de chose to draw them around contiguous architectural features. If in- Arqueología, Universidad Nacional Autónoma de México, D.F. Benavides Castillo, A., 1981. Los caminos de Cobá y sus implicaciones sociales (proyecto dividual superstructures on top of basal platforms are drawn, the ana- cobá). Instituto Nacional de Antropología e Historia, Mexico, D.F. lysis may look somewhat different, emphasizing the fact that how we Bennett, R.R., 1930. The ancient Maya causeway in Yucatan. Indian Notes 7, 347–382. define ‘structures’ matters for the field to compare settlement datasets Brewer, J.L., Carr, C., Dunning, N.P., Walker, D.S., Hernández, A.A., Peuramaki-Brown, between regions. M., Reese-Taylor, K., 2017. Employing airborne lidar and archaeological testing to determine the role of small depressions in water management at the ancient Maya site of Yaxnohcah, Campeche, Mexico. J. Archaeol. Sci. Rep. 13, 291–302. 5. Final comments Canuto, M.A., Estrada-Belli, F., Garrison, T.G., Houston, S.D., Acuña, M.J., Kováč, M., Marken, D., Nondédéo, P., Auld-Thomas, L., Castanet, C., Chatelain, D., Chiriboga, C.R., Drápela, T., Lieskovský, T., Tokovinine, A., Velasquez, A., Fernández-Díaz, J.C., Lidar is becoming an increasingly more common and important Shrestha, R., 2018. Ancient lowland Maya complexity as revealed by airborne laser method in archaeology in general and in tropical forest environments scanning of Northern Guatemala. Science 28 (361). https://doi.org/10.1126/science. such as the Maya lowlands in particular. As the field experiments with aau0137. Cap, B., Yaeger, J., Kathryn Brown, M., 2018. Fidelity Tests of LiDAR Data for the more ways of analyzing and visualizing data, we will continue to make Detection of Ancient Maya Settlement in the Upper Belize River Valley, Belize. large strides in our understanding of past settlement systems. In this Research Reports in Belizean Archaeology 15, 39–51. paper, we have suggested that area and volume density analyses of Chase, A.S.Z., 2017. Residential inequality among the ancient Maya: operationalizing household architectural volume at Caracol, Belize. Res. Rep. Belizean Archaeol. 14, architectural features visible in the bare-earth topography can be an 31–39. important complement to the simple counting of ‘structures’.Ona Chase, A.F., Chase, D.Z., Weishampel, J.F., 2010. Lasers in the jungle: airborne sensors macro-level, polygon count, area, and volume densities can all be easily reveal a vast Maya landscape. Archaeology 63 (4), 27–29. Chase, A.F., Chase, D.Z., Weishampel, J.F., Drake, J.B., Shrestha, R.L., Clint Slatton, K., fi On a more micro-level, however, these used to locate and de ne sites. Awe, J.J., Carter, W.E., 2011. Airborne LiDAR, archaeology, and the ancient Maya different ways of analyzing the data can help us understand the spatial landscape at Caracol, Belize. J. Archaeol. Sci. 38, 387–398. distribution of settlement in different ways; for example highlighting Chase, A.F., Chase, D.Z., Fisher, C.T., Leisz, S.J., Weishampel, J.F., 2012. Geospatial re- monumental constructions or areas of dense settlement such as those volution and remote sensing LiDAR in Mesoamerican archaeology. Proc. Natl. Acad. Sci. USA 109 (32), 12916–12921. found at Yaxuna (Fig. 9). Continued refinement of these techniques has Chase, A.F., Chase, D.Z., Awe, J.J., Weishampel, J.F., Iannone, G., Moyes, H., Yaeger, J., promise and the volume analyses in particular will be important for Kathryn Brown, M., 2014. The Use of LiDAR in understanding the ancient Maya – understanding the labor involved in architectural construction. Re- landscape: Caracol and Western Belize. Adv. Archaeol. Practice 2 (3), 147 160. fi Chase, A.F., Chase, D.Z., Weishampel, J.F., 2013. The use of LiDAR at the Maya site of gardless, how we de ne structures and draw polygons will have a Caracol, Belize. In Mapping Archaeological Landscapes from Space: in Observance of substantial impact on how data are visualized and how comparable the 40th anniversary of the World Heritage Convention, edited by D. Comer and M. datasets will be. As chronological data are slowly collected, archae- Harrower, pp. 179–189. New York: Springer. Collins, R.H., 2018. From sedentism to Sprawl: early urban process at Yaxuná, Yucatan, ologists will continue to make great strides in transforming our Mexico 1000 BCE to 250 CE. Unpublished Ph.D. dissertation, Department of knowledge of how Maya settlement transformed over time.

9 T.W. Stanton, et al. Journal of Archaeological Science: Reports 29 (2020) 102178

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