Volcanism and Valley-fill Sedimentation
Igneous activity associated with the extension occurred from 12 to 4 Ma. Both intrusive (plutonic/solidified underground) and extrusive (volcanic/solidified above ground) igneous rocks were created. Basaltic magma followed fault lines to the surface and erupted as cinder cones and lava flows. Some volcanic rocks were re-worked by hydrothermal systems to form colorful rocks and concentrated mineral formations, such as boron-rich minerals like borax; a Pliocene-aged example is the 4,000-foot (1,200 m)-thick Artist Drive Formation. Gold and silver ores were also concentrated by mineralizing fluids from igneous intrusions. Other times, heat from magma migrating close to the surface would superheat overlaying groundwater until it exploded, not unlike an exploding pressure-cooker, creating blowout craters and tuff rings. One example of such a feature is the roughly 2000 year old and 800 feet (240 m) deep Ubehebe Crater (photo) in the northern part of the park; nearby smaller craters may be less than 200 to 300 years old.
Sediment filled the subsiding Furnace Creek Basin as the area was pulled apart by Basin and Range extension. The resulting 7,000-foot (2,100 m)-thick Furnace Creek Formation is made of lakebed sediments that consist of saline muds, gravels from nearby mountains and ash from the then-active Black Mountain volcanic field. Boron, which is abundant in this formation, is dissolved by ground water and flows out onto the northern end of the Death Valley playa. Today this formation is most-prominently exposed in the badlands at Zabriskie Point. Additional subsidence of the Furnace Creek Basin was filled by the four-million-year-old Funeral Formation, which consists of 2,000 feet (610 m) of conglomerates, sand, mud and volcanic material. Another smaller basin to the south was filled by the Copper Canyon Formation around the same time. Footprints and fossils of camels, horses, and mammoths are in all three of these Pliocene formations.
About 2–3 Ma, in the Pleistocene, continental ice sheets expanded from the polar regions of the globe to cover lower latitudes far north of the region, starting a series of cold glacial periods that were interrupted by warmer interglacial periods. Snowmelt from alpine glaciers on the nearby Sierra Nevada during glacial periods fed rivers that flowed into the valleys of the region year round. Since the topography of the Basin and Range region was largely formed by faulting, not by river erosion, many of the basins have no outlets, meaning they will fill up with water like a bathtub until they overflow into the next basin. So during the cooler and wetter pluvial climates of the glacial periods, much of eastern California, all of Nevada, and western Utah were covered by large lakes separated by linear islands (the present day ranges).
Lake Manly was the lake that filled Death Valley during each glacial period from at least 240,000 years ago to as late as 10,500 years ago; the lake typically dried up during each interglacial period, such as the current one. Lake Manly was the last in a chain of lakes that were fed by 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 585 feet (178 m) deep and 90 miles (140 km) long. Much smaller lakes filled parts of Death Valley during interglacials; the largest of these was 30 feet (9.1 m) deep and lasted from 5000 to 2000 years ago. Panamint Lake filled Panamint Valley to a maximum depth of 900 feet (270 m); 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".
Read more about this topic: Geology Of The Death Valley Area