the Amargosa and Mojave Rivers, and possibly also the Owens River; it was also the lowest point in the Great Basin drainage system. At its height during the Last glacial period some 22,000 years ago, water filled Lake Manly to form a body of water that may have been deep and long. Much smaller lakes filled parts of Death Valley during interglacials; the largest of these was deep and lasted from 5000 to 2000 years ago. Panamint Lake filled Panamint Valley to a maximum depth of ; when it was full, Panamint Lake overflowed into Lake Manly somewhere around the southern end of the Panamint Mountains. Lake Manly and its sister lakes started to dry up about 10,000 years ago as the alpine glaciers that fed the rivers that filled the lakes disappeared and the region became increasingly arid. Fish that had migrated into the lake system from the Colorado River started to die off; the only survivors are the minnow-sized Death Valley pupfish and related species that adapted to living in springs. Ancient weak shorelines called strandlines from Lake Manly can easily be seen on a former island in the lake called Shoreline Butte. Stream gradients increased on flanking mountain ranges as they were uplifted. These swifter moving streams are dry most of the year but have nevertheless cut true river valleys, canyons, and gorges that face Death and Panamint valleys. In this arid environment, alluvial fans form at the mouth of these streams. Very large alluvial fans merged to form continuous alluvial slopes called bajadas along the Panamint Range. The faster uplift along the Black Mountains formed much smaller alluvial fans because older fans are buried under playa sediments before they can grow too large. Slot canyons are often found at the mouths of the streams that feed the fans, and the slot canyons in turn are topped by V-shaped gorges. This forms what looks like a wineglass shape to some people, thus giving them their names, "wineglass canyons". Formation of the Walker Lane - part of an incipient plate boundary? The Quaternary tectonics of the Death Valley area show the increasing impact of right-lateral strike-slip faulting. Death Valley itself is currently an active pull-apart basin developed between the Northern and Southern Death Valley Faults, with mainly normal faulting along the Black Mountains Fault zone between these two major strike-slip fault zones. These faults form part of a