Answer:
(a) The sediments which are deposited by the erosion of Yosemite valley into lake McClure are mostly sand and gravel size.
(b) Most of the sediments that are derived from the Yosemite valley are of igneous nature but if we talk about the sedimentary grains that come from the Yosemite valley than they have very little quartz in they and have both type of feldspar that is potassium feldspar and plagioclase feldspar.