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Originally posted by punkinworks10
Originally posted by punkinworks10
As you have guessed this thread is about ancient California, I chose the name as an omage to Slayer69's many excellent threads, that led down many paths of personal discovery. I hope this one is as entertaining and informative as his.
First the where;
The where is central California's Great San Joaquin Valley, a vast alluvial plain that has been characterized as " the flatest place on earth. Along the nearly 700 mile length of the combined san Joaquin/ Sacramento valleys it only varies in elevation by 300 feet.
The San Joaquin Valley is a sediment-filled depression, called a basin, that is bound to the west by the California Coast Ranges, and to the east by the Sierra Nevadas. It is classified as a forearc basin, which basically means that it is a basin that formed in front of a mountain range.
The Valley dates back more than 65 million years ago to the Mesozoic, when subduction was taking place off the coast of California. However, the plate tectonic configuration of western North America changed during the Tertiary, and the ancient trench that once characterized offshore California was transformed into a zone of right-lateral strike-slip motion that we know today as the San Andreas fault. Nonetheless, the Valley still retains many features that characterized it prior to formation of the San Andreas transform.
Because the San Joaquin Valley is bound to the west by the California Coast Ranges, which represent a zone of folding and thrusting (i.e., an accretionary prism) associated with the ancient subduction zone, and bound to the east by the Sierra Nevadas, which represent the eroded roots of an ancient volcanic arc that was also associated with the subduction zone, some call the valley a remnant arc-trench gap.
The tectonic processes by which this arc-trench gap formed are complicated, as are the events by which the ancient trench became the San Andreas fault. These events are covered in more detail in the plate tectonics section of this website, and the four panels below show a snapshot of the key events.
When the San Joaquin Valley first formed it was an inland sea between two mountain ranges. This configuration remained even after formation of the San Andreas fault (below). However, as the volcanic cover of the Sierras was eroded off, the resulting sediment was dumped into the Valley below. At the same time, The Coast Ranges were also being worn down and dumped into the valley. Thus, the inland sea was filled to create the continental basin we know today.
The maps above show the San Joaquin basin during the middle Miocene (left) and the late Miocene (right) when the principle source rocks were deposited. From these source rocks most of the oil in the valley is derived.
When the basin was still an inland sea, diatoms and other plankton thrived in it, and when these organisms died they accumulated on the basin floor to create organic-rich shales that include the Eocene Kreyenhagen, and Miocene Monterey Formations. The integrated effects of heat and time then acted on the buried organic matter within these shales to create oil, and the detritus eroded from the Coast Ranges and the Sierra Nevadas provided reservoir rocks where the oil could accumulate.
edit on 6-12-2012 by punkinworks10 because: (no reason given)
Tulare Lake, named Laguna de Tache by the Spanish, is a freshwater dry lake with residual wetlands and marshes in southern San Joaquin Valley, California, United States. Until the late 19th century, Tulare Lake was the largest freshwater lake west of the Mississippi River and the second largest freshwater lake entirely in the United States, based upon surface area. The lake dried up after its tributary rivers were diverted for agricultural irrigation and municipal water uses.
The lake was named for the tule rush (Schoenoplectus acutus) that lined the marshes and sloughs of its shores. The lake was part of a 13,670-square-mile (35,400 km 2 ) partially endorheic basin, at the south end of the San Joaquin Valley, where it received water from the Kern, Tule and Kaweah Rivers, as well as from southern distributaries of the Kings. It was separated from the rest of the San Joaquin Valley by tectonic subsidence and alluvial fans extending out from Los Gatos Creek in the Coast Ranges and the Kings River in the Sierra Nevada. Above a threshold elevation of 207 to 210 feet, it overflowed into the San Joaquin River. This happened in 19 of 29 years from 1850 to 1878. No overflows occurred after 1878 due to increasing diversions of tributary waters for agricultural irrigation and municipal water uses, and by 1899, the lake was dry except for residual wetlands and occasional floods.
Tulare Lake was the largest of several similar lakes in its lower basin. Most of the Kern River's flow first went into Kern Lake and Buena Vista Lake via the Kern River and Kern River Slough southwest and south of the site of Bakersfield. If they overflowed, it was through the Kern River channel northwest through tule marshland and Goose Lake, into Tulare Lake.
Yosemite Valley ( /joʊˈsɛmtiː/ yoh-SEM-i-tee) is a glacial valley in Yosemite National Park in the western Sierra Nevada mountains of California, carved out by the Merced River. The valley is about 8 miles (13 km) long and up to a mile deep, surrounded by high granite summits such as Half Dome and El Capitan, and densely forested with pines. A multitude of streams including Tenaya, Illilouette and Bridalveil Creeks join in the valley, and flow out of the valley's mouth as the Merced River, which eventually flows to the Pacific Ocean. The valley is renowned for its natural beauty, and is widely regarded as the centerpiece of Yosemite National Park, attracting visitors from around the world
Originally posted by FinalCountdown
I really thought it was a hit and run
I knida feel bad now.
The Clovis culture (sometimes referred to as the Llano culture  ) is a prehistoric Paleo-Indian culture, named after distinct stone tools that were found at sites near Clovis, New Mexico, in the 1920s and 1930s. The Clovis culture appears around 11,500 RCYBP (radiocarbon years before present  ), at the end of the last glacial period, characterized by the manufacture of "Clovis points" and distinctive bone and ivory tools. Archaeologists' most precise determinations at present suggest that this radiocarbon age is equal to roughly 13,500 to 13,000 calendar years ago.
The Clovis culture was replaced by several more localized regional cultures from the time of the Younger Dryas cold climate period onward. Post-Clovis cultures include the Folsom tradition, Gainey, Suwannee-Simpson, Plainview-Goshen, Cumberland, and Redstone. Each of these is commonly thought to derive directlly from Clovis, in some cases apparently differing only in the length of the fluting on their projectile points. Although this is generally held to be the result of normal cultural change through time,  numerous other reasons have been suggested to be the driving force for the observed changes in the archaeological record, such as an extraterrestrial impact event or post-glacial climate change with numerous faunal extinctions.