Lesson 23 Figure 11 coarse nearshore deposits and fine clay. Continental shelf, while fine sediments cover the sea floor. Calcareous ooze Siliceous ooze Coarse nearshore deposits. Section 14.3 Three types of seafloor sediments, biogenous sediment, and hydrogenous sediment. Terrigenous sediment consists of mineral grains that have been routed from continental rocks and then transported to the ocean.
Samuel Engbring Grand Canyon Paper March 7,2012 Rock Layers of the Grand Canyon The Grand Canyon is an amazing place to see many different layers of rock dating all the back from the Precambrian to the more recent (geologically speaking) Mesozoic era. This canyon was starting to form about five to six million years ago by erosion from the Colorado River and other water sources. On our field trip much of this was seen by our two stops at Cameron and desert view. That gave great overviews of the canyons layers. The oldest of the strata is the Unkar group which dates all the way back to 1,100-1,250 million years ago.
Sediment accumulation of the Juan de Fuca plate may be up to several kilometers thick at the Cascadia deformation front. Early seismic work done by Raitt in 1963 showed a subdivision of the crust into two main seismic layers 2A/2B; this was later expanded to recognize a 3rd layer . These boundaries have been defined by highly porous basaltic lavas, and low-porosity diabase dykes displays p-wave velocities ranging from <2.5 km/s at the ridge axis to >4km/s over mature sections of the ocean crust. The average thickness displayed by layer 2A ranged from 320±80 - 460±80 m. 2B P-wave velocity averages are higher at 5.2 km/s with velocity lows at the ridge axis (4.4±0.3 km/s) and the overall average velocity of mature ocean crust being about 5.2±0.3 km/s. The strongest impact of the velocity difference is thought to be attributed to mineral precipitation around active hydrothermal circulation centres driven by the heat from active hot magma chambers.
It all began 1.5 billion years ago about 50 miles west of current day Glacier National Park. It was here that sediment was being deposited into a very large shallow lake called a sea basin. Over time these layers of sediment were transformed into sedimentary rock formations. One is known as the Appekunny Formation, colors of light green Argillite (slightly metamorphosed mudstone) can be seen in this formation throughout the park today. A burgundy color of Argillite can also be seen in another formation in the park named Grinnell.
What theory did Alfred Wegener propose? The theory of "continental drift" Explain the "continental drift" theory -the edges of the continents make a rough fit -the Appalachian mountain range breaks off in Newfoundland and reappears across the Atlantic ocean in Ireland, Scotland, and Scandinavia -the similarity of European and American fossils up to 180 million years ago and the dissimilarity of more recent fossils What was Wegener's explanation for the 2 predominant elevations of the Earth's surface? Wegener hypothesized that the difference in heights was due to continents being made up of less dense rock that the rocks of the oceanic basins. What did Wegener's hypothesis about the different elevations mean for his theory? It enabled the idea that the lighter and thicker continental blocks to float over the oceanic crust like icebergs What are the arguments against Wegener's theory?
How erosion formed the Grand Canyon How erosion formed the Grand Canyon The Grand Canyon was created by the action of the Colorado River over about 6 million years of erosion. The Colorado River basin has developed in the past 40 million years and the Grand Canyon itself is probably less than 6 million years old. The formation of the Grand Canyon was accomplished by the constant erosion of the rock by the Colorado River over some 17 million years. Over time the river was able to carve a very deep channel into the Colorado Plateau. The rock layers in the Grand Canyon range from 250 million to about 2 billion years old.
Theory 1: Tension forces a) Tension forces act on the layers of rock. b) Gradually two parallel faults appear and the central block begins to subside (sink). c) Land in between sinks in forming a rift valley. The land on either sides stays in place. After subsidence a depression with steep fault scarp sides i.e.
Causes When a dense oceanic plate collides with a less dense continental plate the denser oceanic plate subducts under the less dense continental plate. Japan is situated on the Eurasian plate, which is a continental plate, the pacific plate subducts under the Eurasian plate, forming a deep sea trench. The Indian Ocean Tsunami was caused as the Indian continental Plate was subducted by the Burma plate which is considered part of the Eurasian oceanic plate. When the Oceanic plate subducts under the Continental plate friction and pressure build up and the continental plate can snag on the oceanic plate until the tension is finally released sometimes after millions of years. The break in tension causes a jerk and the sea floor to spring upwards.
One of Yosemite natural wonders are two giant monoliths known as, Half Dome and El Capitan. Half Dome is one of the biggest rocks in Yosemite. Half Dome was made by a glacier during the Ice Age. (National Park Service) The rock soars over 8,842 feet and 4,733 feet above the valley floor. (Shannon Tech) It is located in Yosemite Valley, near Mariposa County on the southeast side of the park.
Sometimes, nature speeds the process up with hurricanes. Barrier islands buffer the mainland from storms and create shelter for a variety of plant and animal species on the islands themselves as well as in the bayous on the mainland. The islands that make up Gulf Islands National Seashore are made of quartz sand eroded and washed down rivers from the Appalachian Mountains. A sand dune these days was possibly once, thousands of years ago, a mountaintop near the South Carolina border. Powerful currents pushed the quartz sand into the Gulf of Mexico.