Photo of the rock faces surrounding the Hetch Hetchy Dam and Reservoir. The bedrock is similar to that of Yosemite Valley, primarily granite, grano-diorite and, to a lesser degree, diorite. The low-water mark is evident against the rock face.
Photo of water being released from the Glen Canyon Dam in Arizona. The bridge that spans the the width of the river gorge is seen above the dam. Grand Canyon National Park begins just downstream of the dam.
Photo of the spillway at the Bonneville Lock and Dam, which slowly releases water from behind the dam back into the Columbia River. The riffles in the flow act as a ladder for spawning fish that allows them to travel upstream.
Photo of people viewing the spillway at the Bonneville Lock and Dam, which slowly releases water back into the Columbia River. The riffles in the flow act as a ladder for spawning fish that allows them to travel upstream.
Photo of the river and cliff faces on the Columbia River Gorge. The basalt cliffs are Miocene (17-12 million years ago). The gorge, however, was carved in the Pleistocene period (2 million - 700,000 years ago) and modified by the Missoula Flood (16,000 - 14,000 years ago).
Photo of the rock material in the area surrounding the Auburn Dam site, specifically depicting the rock size relative to a lens cap. The bedrock is mainly Jurassic/Cretaceous era granitic intrusives, metamorphics, and volcanic tuffs.
Photo of the Crystal Springs Dam located in San Mateo County, specifically depicting the dam face and overlying bridge. This dam was the first "arch dam" built in California. It predates the famous 1906 earthquake and was undamaged from it despite being within 1/4 mile of the San Andreas Fault (which experienced seven feet of offset at this location, but running parallel to the dam).