Pleito Sequence
The Pleito sequence contains four lithologic units: (1) the lower Pleito sandstone, (2) the majority of the lower Tecuya Formation, (3) the middle Pleito mudstone/ sandstone, and (4) the upper Pleito sandstone (Figure 2). The three informal members of the Pleito Formation are interbedded in their easternmost extents with the lower one-third of the Tecuya Formation. In the San Emigdio Canyon area, the Pleito depositional sequence consists of the type section of the Pleito Formation as designated by Nilsen et al (1973), including the lower sandstone, middle mudstone/sandstone, and upper sandstone intervals (Figures 2, 3). The upper sandstone pinches out west of San Emigdio Canyon. At Tecuya Creek, the Pleito sequence consists only of the lower Tecuya Formation. The lower boundary of the sequence is designated as the base of the transgressive boulder-cobble lag on the basal Tecuya conglomerate tongue in the central portion of the outcrop belt. West of the basal Tecuya conglomerate tongue pinch-out, the boundary is the contact between the upper San Emigdio and lower Pleito sandstones. The upper boundary of the Pleito sequence in the San Emig¬dio Canyon area is the top of the upper Pleito sandstone. This boundary is traceable eastward to Pleito Creek, where the upper sandstone interfingers with the Tecuya Formation. The upper boundary of the Pleito sequence is not possible to discern east of Salt Creek because the sequence becomes entirely conglomeratic and domi¬nantly nonmarine.
In the western study area, the Pleito sequence is approximately 1,000 m thick (Nilsen et al, 1973). At the type section in San Emigdio Canyon, the sequence is 614 m thick, and thins gradually eastward to approximately 250 m at its easternmost o...
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.... Regressive facies comprise pro-gradational shelf, nearshore, deltaic, and nonmarine deposits.
2. The San Emigdio and Pleito depositional sequences contain deposits of three contrasting deltaic systems. The lower San Emigdio sequence consists of Gilbert-type delta deposits. The upper San Emigdio and lower Pleito sequences contain shelf fan-delta deposits. The middle and upper parts of the Pleito sequence were deposited by a slope fan-delta.
3. The Eocene to early Miocene tectonic history of the southern San Joaquin basin is divisible into three con¬trasting periods. Regional uplift of Sierran basement during the Paleocene(?) to early Eocene was followed by an episode of rapid subsidence during the middle Eocene. This subsidence may have been driven by a tectonic load associated with the emplacement of the Salinian block to the south and southwest of the study area.
Marshak, S. (2009) Essentials of Geology, 3rd ed. New York: W.W. Norton & Company, ch. 11, p. 298-320.
The shelf-edge includes carbonate-to-clastic facies transition and tectonic uplift and erosion of the carbonates followed by deposition of the clastics. The Saint Peter Sandstone is a well-sorted, almost pure quartz arenite deposited during a major mid-Ordovician low stand. Clastics spread across an exposed carbonate platform by transportation. This is shown by the well-rounded, frosted texture of the quartz grains.
...e morphed it into the quartzite that is seen surrounding the butte (4). Rocks that undergo this process are called metamorphic rock, which is the same as the rock seen years ago by dinosaurs and other extinct creatures. The quartzite rocks were formerly seafloor sediment that was forced upwards, and then surrounded by lava basalt flows. Once erupted through fissures and floods through out most of the area, lava flow eventually created enough basalt to form a thickness of about 1.8 kilometers (1). All of this basalt flow eventually led to the covering of most mountains, leaving the buttes uncovered. The igneous lava flows and loess is reasons that the Palouse consists of such sprawling hills, and rich soil for farming (2). In result of the lava flows, the Precambrian rock Quartzite was formed. And lastly covered by the glacial loess, which were carried by the wind.
Polyphemus is a semi-human, man-eating monster with a single eye in the center of his forehead. He was referred to as a cyclops. He is the son of Poseidon and Thoosa, and lives on an island devoted to cyclops. Polyphemus means abounding in songs and legends.
Gabrysch, R. K. and C.W. Bonnett. "Land Surface subsidence at Seabrook, Texas US." Geological Survey 1977: 21-74. 48 pp.
Many will attest to the grandeur of the natural feature that exists in northern Arizona, but the formation of the Grand Canyon has befuddled geomorphologists to this day. This confusion can be attributed to the Kaibab Plateau, an anomaly considering the Colorado River traverses it seamlessly. Four prevalent hypotheses have been proposed since the 19th century, starting with the lake overflow proposition first brought up by John Newbury and then reinforced by Eliot Blackwelder. Newbury argued that a structure must have ponded an ancient lake causing an overspill to cut into the Grand Canyon. This argument holds that the river must have come after the plateau’s existence. Unbeknownst to Newbury, the structure would be the Kaibab Plateau.
Periods that the folding occurred in which formed the outlines of the basin as it
The sharp differences in elevation between the Badwater Basin and the surrounding mountains that include the highest point in the continental US (Mt. Whitney at 14,494 feet) stand as a representation of the regions violent tectonic past. The mountains themselves are considered fault block mountain ranges meaning that they were formed when blocks of rocks were squeezed through the Earth's crust along parallel faults or were loosened from the crust when it separated at a fault. In the valley, both of these methods not only were the cause of the current mountains formation less than four million years ago, but also are causing the mountains to be uplifted while the valley floor drops even further. This phenomenon is one of the reasons why the lowest and highest points in the continental...
The Grand Canyon is one of the most amazing natural wonders in the world. It was originally deposited sediment that was lithofied, and turned into sedimentary rock. The rock was then carved out by hydraulic processes (Warneke). These processes, all combined, took almost three to six million years to form the Grand Canyon. Continued erosion by wind and rain in the present time continues to shift what the canyon looks like, and make it different as time goes on ("Grand Canyon Facts").
Huang, Ter-chien. The Sediments and Sedimentary Processes of the Eastern Mississippi Cone, Gulf of Mexico. Tallahassee: Florida State University, Sedimentological Research Laboratory, 1969. Print.
Eckel, Edwin B., ed. Nevada Test Site. Memoir 110 Boulder, CO: The Geological Society of America, 1968
...se two tectonic plates generated intense friction and pressure that generated enough heat to melt rocks. The descent of denser oceanic Farallon Plate into the asthenosphere produced magma that was made from basalt or andesite. Which is dark colored rocks with little silica. The buoyant magma pushed through the silica-rich continental crust, partially melting the crust that it moved though, and becoming more granitic in composition. About 100 million years ago, the granitic magma pooled at depths of only 2 to 5 miles beneath the surface (United States of America). The granitic terrain that makes up the Sierra, was once thought to have only local variations but was produced from one large mass of rock. It has been discovered however that hundreds of intrusions caused the variations in the granite that is displayed in Yosemite and in the Sierra Nevada range (Huber).
2000 An Introduction to Grand Canyon Prehistory. Pp 6-7. Grand Canyon, Ariz.: Grand Canyon Association.
Stephen .G,Malcolm.W, Guy H,(2014), GEOL20001 The Geology of Southeast Australia, School of Earth Sciences, University of Melbourne, pg. 23-25
With its abundance of genera, the Burgess Shale is one of the world’s most important fossil fields. It’s discovery in 1909 led to over 100 years of paleontological study in the Canadian Rockies, a majority of which has been carried out in two quarries known as the Walcott and Raymond quarries (Hagadorn, 2002). Though he was originally in search of trilobites in the Burgess Shale Formation, paleontologist Charles Walcott also discovered a diverse group of soft- and hard-bodied fossils, from algae and sponges to chordates and cirripeds (Hagadorn, 2002). Soft-bodied fossils are incredibly rare due to their delicate structure and susceptibility to decay, so it is hard-bodied fossils that more regularly occur in fossil findings. However over 75,000 soft-bodied specimens have been found in the Burgess Shale formation (Hagadorn, 2002). These specimens are preserved in layers of shale formed from deposits of fine mud. One of the most significant species discovered is the Pikaia gracilens. Believed to be an early chordate, the Pikaia gracilens existed very close to the beginning of the evolutionary path that ultimately lead to humans (McGraw-Hill Encyclopedia, 2006).