On behalf of the Texas Department of Transportation (TxDOT), SWCA Environmental Consultants (SWCA) conducted test excavations on the San Antonio River Mammoth site (41BX1239) and 41BX1240 and surveys in the area of potential effects (APE) of the Interstate Highway (IH) 37 bridge project at the San Antonio River in southeastern Bexar County, Texas. Work was initiated to address the requirements of Section 106 of the National Historic Preservation Act (1966) as Amended and the Antiquities Code of Texas. The purpose of the investigations was to identify, delineate, and evaluate the significance of all archaeological and historic properties potentially affected by the undertaking and, if warranted, recommend the scope of additional work. Of particular concern, site 41BX1239 contains the remains of at least two mammoths with possible evidence of cultural association based on the initial investigations by Texas A&M in 1997. However, subsequent faunal analysis, conducted by Olga Potapova and Larry D. Agenbroad of the Mammoth Site in Hot Springs, North Dakota, found inconclusive evidence for definite or valid cultural modification to the specimens studied.

The testing investigations on the San Antonio River Mammoth site included the re-exposure of the original Texas A&M 1997 site trench; limited hand-excavated units to further assess the prior interpretations of the deposits and recover a sample of bone; and a detailed geomorphological assessment. The work identified a bone bed consisting of the remains of at least two mammoths. Flotation of recovered sediments from these hand excavations identified flakes of siliceous material that are consistent with micro-debitage produced by the use and retouch of stone tools.

Although at the highest thresholds of certainty, the cumulative evidence is likely yet insufficient to conclusively prove human interaction with the mammoth remains, the additional data gathered herein lend some credence to the prior interpretation of the site as archaeological rather than strictly paleontological. Concurring with the previous determination, the site is considered eligible for inclusion to the National Register of Historic Places (NRHP) and for listing as a State Archeological Landmark (SAL). However, the investigations determined the site deposits are located outside the APE of the current undertaking, and therefore the project will not affect deposits associated with the San Antonio River Mammoth site.

The investigations of 41BX1240 identified only a very sparse scatter of primarily surficial materials in a heavily disturbed context with no associated features or diagnostic materials. Accordingly, the site is not recommended as eligible for listing on the NRHP or for designation as a SAL. The survey identified no new archaeological sites. Based on the avoidance of 41BX1239, it is SWCA’s recommendation that no archaeological properties will be affected by the IH 37 bridge rehabilitation.

Licensing Statement

This is a work for hire produced for the Texas Department of Transportation (TxDOT), which owns all rights, title, and interest in and to all data and other information developed for this project under its contract with the report producer. The report may be cited and brief passages from this publication may be reproduced without permission provided that credit is given to TxDOT and the firm that produced it. Permission to reprint an entire chapter, section, figures or tables must be obtained in advance from the Supervisor of the Archeological Studies Branch, Environmental Affairs Division, Texas Department of Transportation, 125 East 11th Street, Austin, Texas, 78701

Mammoth_Site_Appendix_A.pdf (5935 kB)
Appendix A

Mammoth_Site_Appendix_B.pdf (2502 kB)
Appendix B

Mammoth_Site_Appendix_D.pdf (545 kB)
Appendix D

Appendix D.xlsx (92 kB)
Appendix D-data

Mammoth_Site_Appendix_E.pdf (281 kB)
Appendix E


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