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. . 5 t""'; CO lJ') - Upstream from the broad floodplain east of Juniper Canyon the Yampa River c. also follows a meandering path. But there, in the segment of the river be- tween Craig and Seeley Ranch, the meanders are cut into deep valleys walled by northward-dipping layers of resistant Cretaceous sandstone. Thus, these meanders are not able to shift laterally as they do on the broad floodplain to the west, and are said to be "entrenched." These entrenched meanders, like Juniper and Cross Mountain Canyons. were formed by the superposition process. Prior to the uplift which initiated the downcutting described previously, the Yampa River apparently meandered freeley across the flat Tertiary sediments which covered the dipping Cretaceous layers. Then, when downcutting was initiated,the river was trapped in its meandering path and, after removing the flat Tertiary strata, eventually entrenched itself through the resistant sandstone layers as they became uncovered by the river's erosion. Another geomorphic process outstandingly displayed in the Juniper - Cross Mountain Project area is mass wasting - the work of gravity. In Cross Moun- tain Canyon especially, one can see abundant evidence of large landslides and rock falls, which, quite obviously, are still actively occurring. The Paleozoic and Precambrian rock strata which make up the steep canyon walls are severely jointed vertically; and high on the canyon walls can be seen many fresh scars where large masses of rock and single boulders have broken away along the joint planes and come tumbling down, producing the abundant talus which has accumulated near river level. Besides being an interesting geological phenomenon, this process poses a real threat to the planned Cross Mountain Canyon Dam. Huge landslides have obviously happened within the recent past, and they will surely happen again.