eater and greater load of sediment. The situation changed in the Mesozoic era about 240 million years ago when a new subduction boundary formed as plates started to dive under the new western edge of North America, drastically changing the landscape of California. Typically, subduction brings about volcanic activity which in this case generated a north-south chain of volcanoes align the length of what is now California, producing the granites of the Sierra Nevada, peninsular Ranges, and Mojave Desert (Sharp and Glazner 4-5).
Clark County is the southernmost county in Nevada, and the rocks in the area include igneous, metamorphic, and sedimentary types. Large exposures of a younger floodplain and its deposits are known as the Las Vegas Formation and are distributed along the Las Vegas Valley. Las Vegas Valley cuts diagonally across most of Clark County and follows a line of strong deformation indicated by bending of the north-trending ridges toward the west along the north side of the valley, and toward the east along the south side of the valley (Longwell, Pampeyan, Bowyer, and Roberts 1-6).
Most of Nevada is desert, and two d
...