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.
Earth and Planetary Sciences
Level of Degree
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
Karas, Paul Arthur. "Quaternary Alluvial Sequence of the Upper Pecos River and a Tributary, Glorieta Creek, North-Central New Mexico." (1988). https://digitalrepository.unm.edu/eps_etds/293