alluvial sediment. Mosaic Canyon Mosaic Canyon is a canyon in the north western mountain face of the valley which is named after a stream-derived breccia sediment with angular blocks of dolomite in a pebbly matrix. The entrance to Mosaic Canyon appears deceptively ordinary, but just a walk up the canyon narrows dramatically to a deep slot cut into the face of Tucki Mountain. Smooth, polished marble walls enclose the trail as it follows the canyon's sinuous curves. The canyon follows faults that formed when the rocky crust of the Death Valley region began stretching just a few million years ago. Running water scoured away at the fault-weakened rock, gradually carving Mosaic canyon. Periodic flash floods carry rocky debris (sediment) eroded from Mosaic Canyon and the surrounding hillsides toward the valley below. At the canyon mouth water spreads out and deposits its sediment load, gradually building up a large wedge-shaped alluvial fan that extends down toward Stovepipe Wells. This canyon was formed through a process of cut and fill which included periodic erosive floods followed by long periods of deposition and uplift. But due to the uplift when the next flood hit the area it would deeply cut the streambed which forms stairstep-shaped banks. Mosaic Canyon's polished marble walls are carved from the Noonday Dolomite and other Precambrian carbonate rocks. These rock formation began as limestone deposited during Late Precambrian (about 850-700 million years ago) when the area was covered by a warm sea. Later addition of magnesium changed the limestone, a rock made of calcium carbonate, to dolomite, a calcium-magnesium carbonate. The dolomite was later deeply buried by younger sediment. Far below the surface, high pressure and temperature altered the dolomite into the metamorphic rock, marble. The Noonday Dolomite has since been tilted from uplift. Mosaic Canyon was named for a rock formation known as the Mosaic Breccia. Breccia is an Italian word meaning gravel. This formation is composed of angular fragments of many different kinds of parent rock, and it can be seen on the floor of the canyon just south of the parking area. Natural Bridge Canyon Natural Bridge Canyon is found on the east side of the park and is one of the few canyons with an official trailhead. Located south of the Artist's Drive scenic loop, the canyon contains a natural stone bridge, accessible after a fifteen-minute walk from the parking area. Panamint Valley The Panamint