Earth and Planetary Sciences ETDs

Publication Date

Winter 12-14-1988

Abstract

Quaternary alluvial deposits preserved on terraces along the Pecos River and a tributary, Glorieta Creek, provide a record of the evolution of these two drainages. Alluvium deposited by the Pecos River can be subdivided into six units on the basis of relative topographic position and degree of soil development on original surfaces. Deposits consist of thin (1 to 10m) veneers on scattered strath terrace remnants. Only four Quaternary alluvial units have been identified along Glorieta Creek. Alluvium deposited by this stream forms nearly continuous fill terraces of thickness equal to or greater than the Pecos River alluvium. Alluvial deposits of the Glorieta Creek basin represent significantly greater sediment storage than the Pecos River terraces given the relative sizes of these two drainages.

Comparison of soil features, particularly calcic and argillic horizon development, with dated soil chronosequences elsewhere in the southwestern U.S. allows estimation of absolute ages for the Quaternary alluvial deposits of the study area. These age estimates are supported by several other relative age-dating tools including soil development indices, pH, organic carbon accumulation, and micromorphological analyses.

Two mid-Pleistocene, one late-Pleistocene, and two Holocene terraces exist along the Pecos River. Alluvial deposits of Glorieta Creek differ from the Pecos river sequence in timing and morphology. One late-Pleistocene and two Holocene terrace levels are preserved in the Glorieta Creek basin. The lack of significant alluvial fill in the Pecos River sequence suggests an overall trend of down-cutting interrupted by periods of relative stability since the mid-Pleistocene. Conversely, alluvium in the Glorieta Creek sub-basin reveals a complex history of late Pleistocene and Holocene aggradation and incision. Dissimilarity in the sequence and morphology of alluvial deposits of the main channel and tributary are probably related to differences in basin size and to the unique response of each fluvial system to changes in internal or external factors.

Degree Name

Earth and Planetary Sciences

Level of Degree

Masters

Department Name

Department of Earth and Planetary Sciences

First Committee Member (Chair)

L. D. McFadden

Second Committee Member

Stephen G. Wells

Third Committee Member

Roger Yates Anderson

Language

English

Document Type

Thesis

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