A piece of land that bifurcates the ancient Maya site of Ek Way Nal, Belize, provides an opportunity to investigate the relationship between sea-level rise, mangrove development, and ancient Maya settlement (Figure 1). Ek Way Nal, with 10 buildings, is one of the largest mapped salt works in Paynes Creek National Park (McKillop Reference McKillop2019; McKillop and Sills Reference McKillop and Sills2022, Reference McKillop and Sills2023; McKillop et al. Reference McKillop, Harlow, April Sievert and Michael2019). Building construction, including salt kitchens and residences, extends from the Late through the Terminal Classic periods (AD 550–900; McKillop and Sills Reference McKillop and Sills2023:Figure 7). The exposed strip of land is covered by living red mangroves (Rhizophora mangle) between Buildings A and D, both radiocarbon dated to the Late Classic, AD 550–800 (McKillop and Sills Reference McKillop and Sills2023). A sediment core was excavated from the strip of land to determine if the ancient site was below the mangroves, with mangrove peat deposited as sea level rose after the site was abandoned. Alternatively, the strip of land may have divided the two areas of the site in antiquity.
Map of the Maya area showing the Paynes Creek Salt Works and selected nearby sites.
Paleoenvironmental studies combined with archaeology provide insights into ancient coastal landscapes, human-environment modifications, and settlement. These approaches combine sea-level rise data with palynology, soil and sediment analysis, and microfossils (Murray-Wallace and Woodroffe Reference Murray-Wallace and D. Woodroffe2014). Multiproxy approaches including sediment cores from nine Lesser Antilles islands reveal human settlement patterns not evident in the archaeological record (Siegel et al. Reference Siegel, Jones, Pearsall, Dunning, Farrell, Duncan, Curtis and Singh2015:276). Similarly, coring a freshwater lagoon in southern Belize, shows that land-use changes are preserved in sediments (Walsh et al. Reference Walsh, Prufer, Culleton and Kennett2014).
In the western Caribbean, sea-level rise varied with topography, increasing 1–3 m over the past 6,000 years (Torrescano and Islebe Reference Torrescano and Islebe2006; Toscano and Macintyre Reference Toscano and Macintyre2003). At the ancient Maya site of Marco Gonzalez sea levels rose a meter in 3,500 years (Dunn and Mazzullo Reference Dunn and Mazzullo1993). At Wild Cane Cay and Pelican Cay, near the Paynes Creek Salt Works, sea-level rise submerged part of both sites. Living red mangroves grow taller to keep their leaves above water, trapping sediment and organic material in their prop roots, forming peat, which is a proxy for sea-level rise (Toscano and Macintyre Reference Toscano and Macintyre2003; McKee et al. Reference McKee, Cahoon and Feller2007; McKillop et al. Reference McKillop, Cory Sills and Harrison2010). The 1.5 m K’ak Naab’ core excavated from the sea floor in Paynes Creek, about 50 m south of the Ek Way Nal core, provides a 4,000-year sea-level record (McKillop et al. Reference McKillop, Cory Sills and Harrison2010). Radiocarbon dated fine red mangrove roots and an average organic content of 65%, comparable to Twin Cays, indicates the rate and timing of sea-level rise (McKee et al. Reference McKee, Cahoon and Feller2007).
At the Ta’ab Nuk Na salt work in Paynes Creek National Park, two marine sediment cores were excavated, one next to a building and one at the site’s western edge (Foster et al. Reference Foster, McKillop and Sills2024). Analysis of the cores indicates that the site was abandoned before sea-level rise submerged the site. This study focuses on excavation and analysis of marine sediment from Ek Way Nal and compares the results with cores from Ka’ak Naab,’ Ta’ab Nuk Na, and Pelican Cay (McKillop Reference McKillop2002; McKillop et al. Reference McKillop, Cory Sills and Harrison2010; Foster et al. Reference Foster, McKillop and Sills2024).
Methods
A 1 × 2 m unit was excavated in 10 cm levels to a depth of 1.7 m on the strip of mangrove land to determine if the site extends beneath the mangrove peat or if the land bisected the site in antiquity (Figure 2). The excavation provided vertical faces from which to extract a column sample (Figures 3 and 4). Seventeen samples were excavated in 10 × 10 cm blocks from the north wall using a stainless-steel knife. The sediment was exported to LSU and refrigerated before study.
A map of Ek Way Nal showing the location of wooden posts and the core on a strip of land bisecting the site.
Photograph of Cher Foster excavating a 10 cm3 marine sediment sample from the Ek Way Nal core.
Results of loss-on ignition from the Ek Way Nal core showing the percent organic matter in 10 cm increments. Shaded region shows cultural material.
Loss-on Ignition
A 2 cm3 sample was taken from the center of each sediment block, placed into labeled tinfoil trays, and dried in an oven at 60°C for 24 hours. The samples were removed and ground using a mortar and pestle until the contents passed through a No. 25 geological (fine mesh) sieve. The samples were placed in labeled ceramic crucibles, weighed, and put in a muffle furnace at 105°C for four hours. They were removed, weighed, and placed in the muffle furnace. They were burned for eight hours at 600°C to remove all organic matter, removed, and weighed again.
Microscopic Sorting
Separate samples were taken from six levels of the core for microscopic sorting. Each sample was placed in a No. 25 geological sieve, rinsed to remove loose sediment, and placed in a petri dish of water. The material in the petri dishes was viewed under a microscope. Needle-nosed tweezers were used to separate items and place them into labeled 12 mL glass vials according to material (fine red mangrove roots, coarse red mangrove roots, pottery, quartz sand, stone, and wood). The fine red mangrove roots were removed from their vials and weighed wet on an electronic balance. They were then placed in a drying oven in their glass vials for six hours at 60°C. The roots were weighed again for a dry weight and archived (Foster et al. Reference Foster, McKillop and Sills2024).
Results
Cultural material excavated from the 1 × 2 m unit was recovered from 20 to 100 cm depth with the highest densities from 30 to 60 cm (Foster et al. Reference Foster, McKillop and Sills2023:Figure 8). Most artifacts were briquetage—broken pieces of pottery used in boiling brine over fires to make salt (McKillop Reference McKillop2002, Reference McKillop2019; McKillop and Sills Reference McKillop and Sills2023). Charcoal was recovered from 30 to 90 cm with the highest density, approximately 4,000 pieces, from 40 to 50 cm (Foster et al. Reference Foster, McKillop and Sills2023:Figure 10). The native palm endocarps Attalea cohune (cohune) and Acrocomia aculeata (coyol) were found from 30 to 80 cm (Foster et al. Reference Foster, McKillop and Sills2023:Figure 11).
Loss-on ignition revealed variability in the percentage of organic matter in the marine sediment, ranging from 25.4% to 78.4% (Figure 4). The average organic matter was 53.38%. The highest values for organic matter (above 70%) were from 60 to 70 cm and 130–174 cm depth.
All sediment sorted microscopically contained fine and coarse red mangrove roots (Table 1). The identification of red mangroves forming the organic component of the sediment, together with the high organic content identified from LOI, is consistent with the definition of red mangrove peat (McKee et al. Reference McKee, Cahoon and Feller2007). Quartz sand and charcoal were present from 0 to 60 cm but absent in levels 80–90 cm and 160–170 cm. Pottery was found in samples 20–50 cm. The weight of dry roots ranged from 0.01 to 0.43 g. The heaviest weight of fine red mangrove roots was from 20 to 30 cm depth. The lowest was from 10 to 20 cm and 160–170 cm depth.
Results of Microscopic Sorting Including Fine R. mangle Roots (g) and if the Samples Contained Coarse Roots, Charcoal, Quartz, and/or Pottery.
The Relationship between Mangrove Development and Site Occupation
The Ek Way Nal sediment column documents sea-level rise by red mangrove peat before and after occupation. The peat above the cultural levels indicates that red mangroves grew in shallow water post-abandonment, sometime after AD 765–906 based on radiocarbon dated nearby wooden building posts (McKillop and Sills Reference McKillop and Sills2023). A similar record of mangrove development occurred at Ta’ab Nuk Na, where mangrove peat was radiocarbon dated to Postclassic and historic times (Foster et al. Reference Foster, McKillop and Sills2024; see Flynt et al. Reference Flynt, McKillop and Sills2026). Artifacts embedded in the mangrove peat to the north and south of the strip of land at Ek Way Nal indicate that red mangroves grew after the site was abandoned.
Loss-on ignition at Ek Way Nal shows higher organic matter in the lower levels compared to the upper levels, which include cultural material. Site occupation and the introduction of pottery and other cultural material changed the composition of the marine sediment and reduced the organic content. Similar findings are from Ta’ab Nuk Na, where marine sediment cores averaged 27% organic content (Foster et al. Reference Foster, McKillop and Sills2024), compared to 65% in the off-site core at K’ak Naab’ (McKillop et al. Reference McKillop, Cory Sills and Harrison2010). Microscopic sorting reveals that the Ek Way Nal core is comprised of fine red mangrove roots indicating continuous sea-level rise. Dry root weights at the western edge of Ta’ab Nuk Na range from 0.05 to 0.14 g, whereas near a building they range from 0.04 to 0.09 g (Foster et al. Reference Foster, McKillop and Sills2024). In contrast, dry root weights at Ek Way Nal range from 0.01 to 0.43 g with heaviest weights between 20 and 40 cm. Quartz sand in the sediment core derives from sand-tempered pottery. Charcoal in the cultural levels reflects ancient Maya wood burning in antiquity. An absence of charcoal, quartz sand, and pottery in the lower sections of the sediment core suggests no human impact before the Late Classic period.
The red mangrove peat on the strip of land at Ek Way Nal resembles the Maya site on Pelican Cay, a nearby offshore island (McKillop Reference McKillop2002:156–159). Excavations revealed red mangrove peat devoid of artifacts to 40 cm depth. Pottery sherds, charcoal, and palm endocarps were found between 40 and 70 cm depth. The soil was mangrove peat mixed with gray mud between 40 and 60 cm depth, with white sand and finger coral (Porites spp.) between 60 and 115 cm depth. Below 115 cm was a mangrove peat layer devoid of artifacts (McKillop Reference McKillop2002:Figure 5.6). Wood charcoal from the cultural deposits was radiocarbon dated to cal AD 450–650, placing the site from the end of the Early Classic (AD 250–550) to the beginning of the Late Classic (AD 550–800; McKillop Reference McKillop2002:158).
The K’ak’Naab’ core provides an off-site comparison of sea-level rise for the nearby Ek Way Nal core, but without admixture of cultural material. The Ka’k’ Naab’ core was extracted from the sea floor 45 cm below the water surface to a depth of 150 cm. Loss-on ignition indicates the organic content is high, averaging 65% (McKillop et al. Reference McKillop, Cory Sills and Harrison2010:Figure 2). The sediment was primarily R. mangle roots. The depths of radiocarbon-dated layers below the water surface were used to evaluate the timing and rate of sea-level rise. The ground surface at the beginning of the Early Classic (cal AD 410–590) was 132.7 cm below modern sea level. The end of the Late Classic (cal AD 1020–1200) was 75.2 cm below modern sea level. Sea levels rose a total of 57.7 cm during the Classic period, which is a rate of 0.087 cm per annum (McKillop et al. Reference McKillop, Cory Sills and Harrison2010:203–204). This corresponds to the late Holocene sea-level curves reported elsewhere in the Caribbean (Toscano and Macintyre Reference Toscano and Macintyre2003).
Conclusions
A 1.7 m sediment column from Ek Way Nal records sea-level rise before, during, and after site occupation. Loss-on ignition indicates highly organic sediment, with fine red mangrove roots, a proxy for sea-level rise. The presence of cultural material from 20 to 100 cm depth records continuous settlement through the modern strip of land. Red mangrove peat above the cultural levels shows sea-level rise after the site was abandoned. The nearby island site of Pelican Cay with 40 cm of red mangrove peat above the site also shows sea-level rise after abandonment. Sea level also rose after Ta’ab Nuk Na was abandoned, as indicated by mangrove peat deposition followed by flooding, which left the site underwater (Foster et al. Reference Foster, McKillop and Sills2024).
The K’ak’ Naab’ core, located off-site near Ek Way Nal, revealed continuous sea-level rise during the Classic period, at a rate of 0.08 cm per annum (McKillop et al. Reference McKillop, Cory Sills and Harrison2010:203–204). This is consistent with rates of sea-level rise elsewhere in the Caribbean and western Atlantic (Toscano and Macintyre Reference Toscano and Macintyre2003; Torrescano and Islebe Reference Torrescano and Islebe2006) and provides a temporal framework for the Ek Way Nal core. The documentation of Classic Maya sites such as Ek Way Nal partially or completely buried under red mangroves suggests that other ancient Maya sites are hidden in the modern mangrove landscape of Belize, along the Yucatán coast of Mexico, and in tropical landscapes worldwide where mangroves grow.
Acknowledgments
The research was carried out under excavation permit IA/H/2/1/22(05) and export permit IA/H/3/1/19(02) in 2019 to Heather McKillop from the Belize Institute of Archaeology. The field team included Rachel Watson, Hollie Lincoln, Rianna Bowen, Kaitlin Samples, Conner Flynt, John Young, and the authors. We thank Amy Hernandez, Amanda Meaux, and Josephine Hanegan for assistance with microscopic sorting and loss-on ignition.
Funding Statement
This research was supported by the National Science Foundation under Grant 1826653 to Heather McKillop and E. Cory Sills.
Data Availability Statement
Remaining sediment samples are stored in the archaeology laboratory at LSU, Baton Rouge. Digital documents are catalogued with the Underwater Maya Project materials at LSU and UT Tyler.
Competing Interests
The authors declare none.
