Shoreline Butte

Shoreline Butte. Prehistoric Shores. , Prehistoric Shores , Prehistoric Lake Manly, fed by melting Sierra Nevada glaciers and surrounded by trees, would have looked very different from what you now see. With no exit from the valley, the lake grew to a depth of 500 to 600 feet and stretched for 100 miles, leaving Shoreline Butte as an island , and this spot was under 400 feet of water! , , Today, ancient beach lines on Shoreline Butte mark the fluctuating levels of Lake Manly like rings around a bathtub. Wind-driven waves deposited sand and gravel or eroded cliffs along the water's edge, creating features known as strandlines. Geologists have identified more than 12 strandlines, which are best observed when the sun is at a low angle. At the base of Shoreline Butte is the Amargosa River, an intermittent waterway that flows underground for most of its 185-mile length, or after heavy rainstorms drain into the valley. , , Runoff from cooler and wetter climatic conditions during the last Ice Age created five large lakes that gradually disappeared as average temperatures increased and moisture decreased. , , original marker text: , Lake Manly , How vivid is your imagination? , Can you visualize the desert scene before you as it would have appeared approximately 20,000 years ago? Imagine, if you can, this valley filled with a lake, 90 miles long, 6 to 11 miles wide and up to 600 feet deep. Feel the cool wind on your face as it blows down the lake from the north. Can you see and hear the wind driven waves, rhythmically washing against the dark basaltic lava butte before you? If your mind has conjured up these images, then you have "seen" Pleistocene Lake Manly., Lake Manly existed here as an indirect effect of glaciation during the Ice Age. As glaciers in the Sierra Nevada began to melt due to climatic changes during this period, water flowed from the mountains and filled the low lying areas or basins. As one basin filled, water overflowed into another (see diagram). In this manner Owens Lake was formed and overflowed south through Rose Valley and into Indian Wells Valley forming China Lake. China Lake spilled over into Searles Basin producing Searles Lake which then flowed through the Slate Range filling Panamint Valley. Upon reaching the level of Wingate Pass at 1,976 feet, Panamint Lake spilled over into Death Valley creating Lake Manly. This process occurred in several stages., Lake Manly dried up about 10,000 years ago. Since that time the Valley has been dry and subject to seasonal flooding except for a period about 2,000 years ago when water accumulated to form a pond about 30 feet deep. It, too, has disappeared., If you look closely, you will notice a series of horizontal terraces or benches running roughly parallel across the butte before you. Exposed to the full force of wind driven waves, these terraces are actually ancient shorelines carved by the relentless action of the waves. Among the best evidence for the existence of Lake Manly, these terraces also represent evidence of its fluctuating water level. From these shorelines comes the name for this feature , Shoreline Butte. How many distinct terraces can you count?, If you are traveling north through Death Valley you may wish to look for other evidence of Lake Manly. Similar faint shorelines are visible at Mormon Point. North of furnace Creek, about 1.8 miles along the route to Beatty, the road cuts through a gravel bar of water worn pebbles and cobbles that still mark the shoreline of this ancient lake., At least four other episodes of glacial advances and retreats have occurred during the last 2 million years. Lake Manly was formed as a result of one of these episodes. There may have been similar lakes here prior to Lake Manly. This recurring cycle of events can only provoke us to wonder if sometime in the future another lake of glacial origin will again cover the floor of Death Valley.