GEOMORPHOLOGY OF TERRACES AND MORAINES IN THE UPPER RIO GRANDE BASIN, SAN JUAN MOUNTAINS, COLORADO, USA

Continuing research was conducted in the summer of 2016 to determine the relationships between soil development and age on glacial moraines and stream terraces in the upper Rio Grande Basin. The purpose is to model landscape evolution in the basin and study changing environments of the late Pleistocene and Holocene in the San Juan Mountains. In the South Fork study area, glacial moraines are related to the high river terraces (T1). There is a sequence of four terraces in both the South Fork and Rio Grande study areas. Research methods involve field mapping of moraines and fluvial terraces, field and laboratory analysis of soils, and the integration of GIS. Preliminary results link the lowest terrace (T4) of these high-order streams to terrace construction in lower-order tributaries (Carver and Beeton, 2014) and links the highest terraces (T1) to the Last Glacial Maximum. Submitted OSL and 14C samples, combined with the degree of soil development will help establish relationships between moraines, terraces, and climate change.