College of Agricultural, Food, and Environmental Sciences
Natural Resources Management and Environmental Sciences Department
BS in Environmental Earth & Soil Sciences
Rainbow Basin and Owl Canyon comprise deeply dissected uplands in the Mud Hills region near Barstow, California in the western portion of the Basin and Range geologic province. These erosional landscapes are formed in sediment deposited in a Miocene-time extensional basin. The basin was then filled with sediment before being inverted due to tectonic uplift beginning roughly 10 Ma. Sometime after 250 to 300 ka strath terraces were produced and preserved in the two drainage basins in Rainbow Basin, but not in the single drainage basin of Owl Canyon. The reason behind this difference is the main problem to be addressed by this study. This difference is ultimately explained by a contrast in critical stream power between the drainage basins stemming from a difference in the amount of sediment denuded from the hillslopes of the different catchments. Severe winter Pacific storms occurring between 11 and 14 ka may have led to the production and preservation of erosional strath terraces in Rainbow Basin while causing the aggradation of the channel in Owl Canyon. These severe winter storms tend to cause more denudation in larger drainages. Because the catchment of Owl Canyon is roughly three times the size of either of the catchments in Rainbow Basin, it is not unreasonable that this phenomenon would have raised critical steam power relative to stream power in Owl Canyon to a degree that it would cause aggradation in Owl Canyon while allowing strath production and sedimentation in Rainbow Basin.