Archaeology and Volcanism

V. Mesoamerican Archaeological Sites

A. Probable Effects of the Ilopango Eruption on Maya Cultural Development

Volcanic activity has also preserved a number of important archaeological sites in the New World. During the third century A.D., a caldera-forming eruption of the Volcan Ilopango devastated the highlands of El Salvador, Central America, covering a broad area under pyroclastic flows and a much larger region under thick layers of tephra. Whereas land lying within a radius of about 60 miles of the vent was rendered completely uninhabitable, areas lying father away suffered varying degrees of environmental damage, leaving a large population of survivors with no means of subsistence. Recent studies by Payson Sheets and others suggest that the eruption, occurring at the close of the Proto-classic Maya period (A.D. 200-300), had unusually long-term social and economic effects on the evolution of Maya culture. Besides totally destroying farmlands and villages in the most severely impacted zone around the volcano and disrupting agricultural production over a vast region, the eruption may also have been responsible for a massive redistribution of the Maya population, causing an estimated 320,000 survivors to migrate northward from Salvador to Belize and northern Guatemala. The influx of migrants, displaced by the Ilopango event, may have been a catalyst that helped accelerate the already in-progress development of Classic Maya civilization. Flooding lowland towns and villages north of Ilopango, these tens of thousands of refugees may have stimulated rapid social and political responses by the Maya leadership to accommodate the suddenly increased populations. After the eruption forced abandonment of the major highland trade route, rulers at Tikal gained control of regional commerce.

Excavations at sites scattered over central and western El Salvador which were affected by the Ilopango cataclysm reveal a wealth of Preclassic Maya artifacts. Located about 40 miles from Ilopango, pre-eruption Chalchuapa was a major residential, economic, and ritual center in the southeast Maya highlands, featuring numerous 50 foot high pyramids arranged around open plazas and elaborately sculptured monuments, some of which bore calendric dates. Numerous ceramic vessels, some with polychrome painting, were found under Ilopango's ubiquitous layer of light-colored ash, known locally as the tierra blanca. Digs at rural sites have uncovered farms, fields (many apparently irrigated), and villages The ruins of a farmhouse at the village of Joya de Ceren, buried under 16 feet of ash, disclosed much about the Maya villagers' diet and way of life, indicating that they ate corn, wild and domesticated beans, and squash, liberally spiced with an array of chilies. Enjoying a variety of shellfish, they cooked their food in cottonseed oil and wove cotton cloth that they may have traded for obsidian, a desirable raw material for tools in the New as well as the Old World.

B. Mount Arenal and the Prehistoric Culture of Costa Rica

In contrast to the long-term effects of the Ilopango disaster, repeated eruptions of the Mount Arenal in the rainforests of northwest Costa Rica do not seem to have had a significantly disruptive impact on the native population. Sheets' investigations around Arenal, one of Central America's most active volcanoes, indicates that village life, established about 2000 B.C., was remarkably stable. Despite at least nine explosive outbursts during the prehistoric period, villagers were resilient and maintained permanent settlements near the volcano. Whereas the Ilopango paroxysm was large enough to generate massive changes in Mayan society and mark a definable boundary between distinctive phases of Mayan cultural development, the frequent Arenal eruptions—averaging four per century—did not effect a comparable alternation in the culture of prehistoric Costa Rica. Aerial photographic surveys and digital remote sensing devices have detected numerous linear anomalies in the region, many of which have been identified as prehistoric footpaths, representing a long-established system of transportation and communication through the rainforests that persisted in spite of Arenal's many explosive eruptions.

GlossaryVolcanoes as Preservers of Archaeological SitesHerculaneum and Pompeii: Cities of the Early Roman EmpireAkrotiri: An Aegean Bronze Age CityCatal Huyuk: The Earliest Representation of a Volcanic EruptionMesoamerican Archaeological SitesNorth American Archaeological SitesGeomythology: Volcanoes in Prehistoric Oral TraditionsSummary

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