New Mexico Geological Society Annual Spring Meeting — Abstracts

The Llano Estacado (or Southern High Plains) of northwestern Texas and eastern New Mexico has one of the highest concentrations of the oldest (“Paleoindian” 11,500-8000 ¹⁴C years B.P.) archaeological sites in North America, including such well-known localities as Lubbock Lake, Clovis, Plainview, and Midland. Research on these Paleoindian localities began in the 1930s and resulted in some f the earliest stratigraphic and chronologic sequences for the Paleoindian occupation of North America. Geologic studies were an integral part of the work at the outset.

Most of the intensely investigated Paleoindian sites are in the three settings where archaeological sites are preserved in well-stratified contexts: draws, playas, and dunes. The draws are now-dry tributary valleys of the Colorado and Brazos Rivers, which contained flowing streams, ponds or marshes during Paleoindian times. The playas are small, shallow basins numbering in the thousands which dot the High Plains landscape and once contained permanent lakes. The dunes include extensive sand dune fields that were initiated during the Paleoindian occupation, and small dunes that fringe some playas.

Geoarchaeological research in the broader context of late-Quaternary stratigraphy, soils, landscape evolution, and paleontology provide important clues to the changing environments of Paleoindian hunter-gatherers. The first (Clovis 11,500-11,000 ¹⁴C years B.P.) occupants of the area found abundant water in draws and playas, and game, including a variety of nowextinct fauna such as mammoth, camel, horse, and bison. Later (11,000-10,000 ¹⁴C years B.P.) inhabitants likewise lived among a diverse array of resources, perhaps reflected in the large number of sites and wide array of artifact styles for this period (Folsom, Midland, Plainview, Milnesand). The time is also characterized by extinction of most megafauna, and increasing aridity with a declining water table. Late Paleoindian times (10,000-8000 ¹⁴C years B.P.), characterized by Firstview and related unfluted lanceolate projectile points witnessed further aridity and declining water in draws and playas along with formation of dunes on uplands. Site frequencies also decline. This environmental and archaeological trend culminates in the prolonged aridity of the early-middle Holocene “Altithermal.”