Texas Historical Commission




In January through March 1993, archeological and geomorphological investigations were conducted at two clay dune sites, 41WY50 and 41WY60, in the outfall area of the Hidalgo-Willacy Drainage Ditch system. This work represents the final investigations of a cultural resource management program conducted for the U.S. Army Corps of Engineers and the local sponsors, Hidalgo County Drainage District No. 1 and Willacy County Drainage District No. I, by Prewitt and Associates, Inc. The results of the archeological investigations were poor. Neither site yielded materials of unquestionable cultural origin, although several small basin-shaped hearth features were encountered. Based on radiocarbon assays from soil humates and the stratigraphic provenience of the features, it is speculated that the occupation(s) at 41WY50 is late Archaic and the occupation(s) at 41WY60 is Late Prehistoric to Historic. Both sites represent very short term occupations and most likely do not represent repetitive use on a seasonal or yearly basis. These investigations suggest that, since the development of the modem coastal environments approximately 3,000 to 4,000 years ago, the south Texas coast between Baffin Bay and the Holocene delta of the Rio Grande has been a resource-poor and inhospitable area that probably was utilized only sparsely or intermittently. The geomorphological investigations were more successful, adding valuable data ahout paleoenvironments and the formation of the modem coastal environments of the Lower Rio Grande Valley. The clay dunes formed through the eolian transport of fine to very fine quartz sand and fine to very fine sand-sized aggregates of clay from adjacent wind-tidal flats during the late Holocene. Stable carbon isotope studies of soil humates suggest that the clay dune plant community was and still is dominated by C, and/or CAM plants. These investigations also disclosed fluctuations in sea level during the late Holocene. An abandoned wind-tidal flat, encountered at 41WY50, indicates that sea level was at least I m higher than present mean sea level between 2300-1100 B.P.


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