Jurassic-age volcanic rocks (see the top of the timescale image). Stretching and lakes Basin and Range-associated stretching of large parts of crust below southwestern United States and northwestern Mexico started around 16 million years ago and the region is still spreading. This stretching began to affect the Death and Panamint valleys area by 3 million years ago. Before this, rocks now in the Panamint Range were on top of rocks that would become the Black Mountains and the Cottonwood Mountains. Lateral and vertical transport of these blocks was accomplished by movement on normal faults. Right-lateral movement along strike-slip faults that run parallel to and at the base of the ranges also helped to develop the area. Torsional forces, probably associated with northwesterly movement of the Pacific Plate along the San Andreas Fault (west of the region), is responsible for the lateral movement. Igneous activity associated with this stretching occurred from 12 million to 4 million years ago. Sedimentation is concentrated in valleys (basins) from material eroded from adjacent ranges. The amount of sediment deposited has roughly kept up with this subsidence, resulting in the retention of more or less the same valley floor elevation over time. Pleistocene ice ages started 2 million years ago, and melt from alpine glaciers on the nearby Sierra Nevada Mountains fed a series of lakes that filled Death and Panamint valleys and surrounding basins (see the top of the timescale image). The lake that filled Death Valley was the last of a chain of lakes fed by the Amargosa and Mojave Rivers, and possibly also the Owens River. The large lake that covered much of Death Valley's floor, which geologists call Lake Manly, started to dry up 10,500 years ago. Salt pans and playas were created as ice age glaciers retreated, thus drastically reducing the lakes' water source. Only faint shorelines are left. Biology Habitat varies from salt pan at below sea level to the sub-alpine conditions found on the summit of Telescope Peak, which rises to . Vegetation zones include creosote bush, desert holly, and mesquite at the lower elevations and sage up through shadscale, blackbrush, Joshua tree, pinyon-juniper, to limber pine and bristlecone pine woodlands. The salt pan is devoid of vegetation, and the rest of the valley floor and lower slopes have sparse cover, although where water is available, an abundance of vegetation is usually present. These zones and the adjacent desert