Trade and Inter-Community Networks Around Managua, Nicaragua

CHIQUILISTAGUA ARCHAEOLOGY PROJECT

Land Cover

Chiquilistagua Archaeological Project Trade and Inter-Community Networks Around Managua, Nicaragua Evan Sternberg, Justin P. Lowry, and Jason S.R. Paling Trade and inter-community connections are keys to understanding how the ancient region around the modern city of Managua, Nicaragua, interacted and participated in the larger Central American and Mesoamerican trade corridor. This poster will present potential interpretations of long distance and local connections through a cost and pathway analysis using ArcGIS. This study will incorporate recent research on obsidian sources from the site of Chiquilistagua into the model of interactions, as well as an analysis of ceramic spheres. Adapting site catchment areas, using trade and pathway data, and incorporating sourcing analyses we can help to identify potential connections between sites and regions. These models may then be tested in future excavations around Managua, Nicaragua, to evaluate their utility.

Travel Speed Surface

This geospatial model is an attempt to reconstruct the material limitations that exist in the environment and which provide the physical limitations of travel and trade. By creating a regional and inter-regional scale analysis of Lower Central America we can then evaluate the assumption that the easiest and fastest paths would have been the actual locations of trade routes. This model uses data from elevation models (Shuttle Radar Topography Mission [SRTM] 1 Arc-Second), land cover data (Global Land Cover Characterization [GLCC]), and estimates for speed of foot travel for hikers (see NPS Trail Model).

Archaeological Sites

Obsidian Sources

Chiquilistagua

Guinope

Nindiri (see Sheets et al. 1990)

Ixtepeque

Vidor, Costa Rica (see Sheets et al. 1990)

Ixtepeque

Ni-Mt-Td-004

Guinope

Ni-Mt-Td-005

Guinope

Ni-Mt-Td-017

Guinope

Guinope

Guinope

Travel Cost Pathway – Local Source

These data were then combined to perform a travel cost model. First, we created a travel surface that incorporated speed based on elevation and subsequently combined land class based evaluations of relative speed. Here we incorporated the same Percent of Maximum Travel Speed (PMTS) values for elevation and land cover as the NPS Trail Model (2010). Water locations in the land cover data were all assigned 100% travel speed PMTS values, assuming the common use of water-based transport in the ancient trade networks of Mesoamerica (Drennan 1984). The final travel speed surface incorporates all previous layers as a mechanism for evaluating travel speeds in different elevations and land cover classes.

Cost Distance Surface

Back Link Surface

Digital Elevation Model

The future analysis of these models must include more nuanced measures of water-based transport (per Callahan 2003 and ORBIS http://orbis.stanford.edu/). Additionally, models for river navigation must be created that account for the size and feasibility of river transport. With the advancement of geographic models, we must also consider the importance of a comprehensive, chronologically grounded, atlas of archaeological sites for this region, as one does not currently exist. Another limitation to this model is the reliance on modern land cover classes. We may benefit from a paleoecological reconstruction of ancient land cover classes (see Gaillard et al. 2010). Once complete, these models should be tested against archaeological datasets and trade data to establish a baseline expectation for locations of trade routes, and with enough comparative data we can map the relative volume of interregional trade. Citations: Callaghan, R. T. 2003 “Prehistoric trade between Ecuador and West Mexico: A computer simulation of coastal voyages.” Antiquity, 77(298), 796804. Drennan, Robert D. 1984 "Long‐distance transport costs in pre‐Hispanic Mesoamerica." American Anthropologist 86, no. 1 105-112.

Travel pathways were then evaluated from associated locations with known trade connections. For this aspect, we relied on recent obsidian sourcing analysis conducted as part of the Chiquilistagua Archaeological Project (CAP), and described in Colin Quinn’s thesis (2015). A few (unpublished) obsidian pieces from Matagalpa, Nicaragua, and additional locations for sources and sites were taken from published results (see Sheets et al 1990). With these sites in mind, a cost distance raster was calculated, where each cell in the raster represents the accumulated distance and cost from origin points (Obsidian Sources). Second, a backlink surface was created, where each cell in the raster represents the least cost direction to those origin points (Obsidian Sources). Finally, a least cost pathway was created to connect destinations (archaeological sites) to each obsidian source along the cost distance and backlink surfaces.

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