The exposed geology of the Death Valley area records many events
associated with plate tectonics. The oldest rocks in the area that now
comprise Death Valley National Park and environs are extensively
metamorphosed by intense heat and pressure and are at least 1700
million years old. Rifting of the supercontinent Rodinia some 700 to
800 million years ago (mya) allowed sea water to invade until the
continental crust broke, giving birth to the Pacific Ocean. The
region's first known fossils of complex life were buried at the base
of the submerged precipice. Some 80 million years ago a subduction
zone formed off the coast as the Farallon Plate started to dive below
the North American Plate; volcanoes and uplifting mountains were
created in the region as a result. Stretching of the crust under
western North America started around 16 mya, creating the Basin and
Range province. By 2 to 3 mya this province had spread to the Death
Valley area, ripping it apart and creating Death Valley, Panamint
Valley and surrounding ranges. These valleys partially filled with
sediment and, during the wet times of ice ages, with lakes such as
Lake Manly. By 10,500 years ago these lakes were increasingly cut off
from glacial melt from the Sierra Nevada, starving them of water and
concentrating salts and minerals. The desert environment seen today
developed after these lakes dried up.
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Today's selected anniversaries:
Thomas Edison received a patent for his mimeograph machine.
German airship LZ 127 Graf Zeppelin embarked on a flight to
circumnavigate the world.
Betty Boop made her first appearance as an animated cartoon character
in Max Fleischer's Talkartoon.
Holocaust: The Mauthausen concentration camp was opened.
Indonesia, Malaysia, the Philippines, Singapore and Thailand founded
the Association of Southeast Asian Nations.
Wikiquote of the day:
"It seems that if one is working from the point of view of getting
beauty in one's equations, and if one has really a sound insight, one
is on a sure line of progress." -- Paul Dirac