Tectonic processes active in the Cascadia subduction zone region include accretion, subduction, deep earthquakes, and active volcanism of the Cascades. This volcanism has included such notable eruptions as Mount Mazama (Crater Lake) about 7,500 years ago, Mount Meager about 2,350 years ago, and Mount St. Helens in 1980. Major cities affected by a disturbance in this subduction zone would include Vancouver and Victoria, British Columbia; Seattle, Washington; and Portland, Oregon. The two tectonic plates involved in the subduction process at the convergent fault line are the Juan de Fuca plate and the North American plate. The Juan De Fuca plate being the denser oceanic plate is being subducted under the continental North American plate.
Jewel Cave is located in the Black Hills of South Dakota. The Black Hills were formed during the Tertiary Lamanide Oroginy. (See Figure 2 and 7). The Black Hills are doubly asymmetrical anticlines that are plunging to form a dome. Two rock types are from the Tertiary and the Quaternary period and are starting to intrude into the older rock types.
INTRODUCTION The Cretaceous Period, spanning 65.5-146 million years ago (Mya), was a world different from what we are familiar with today. Planetary changes during this period included the extinction of dinosaurs and drastic global warming. The breakup of the super continent Pangea had started about 30 Mya, and seaways had begun to form and cover landmass that had once been a part of the super continent (Geologic Time). Today, scientists know that one of these landmasses, the North American continent as we now know it, was at one point covered by a vast inland sea known as the Western Interior Seaway. The Seaway stretched from the Arctic Circle down to the warm waters of the Gulf of Mexico, and spanned most of the continent.
Along the southern boundary were three separate arches which were rising due to the Taconic orogeny: Kankakee, Findlay, and Cincinnati. The upward movement of these arches were integral in the depressive basins forming adjacent to them: Michigan, Illinois, and Appalachian. However, the original weakening of the continental lithosphere is suggested to have been caused by the introduction of a rising diaper (Haxby, Turcotte, Bird 1976). Erosional and weathered material from the nearby forming mountains were transported and deposited into the many basins west of the mountain belt. The sediment would continue to accumulate and accentuate the subsidence which was occurring and further deepen the basin.
Approximately 25 million years ago, all of Eastern Washington was flooded due to the eruption of the Columbia River Basalts. As the molten rock came to the surface, the Earth 's crust gradually sank into the space left by the rising lava. Explosions of magma filled the area and the coverage was extensive. The now Columbia River Plateau was filled with basalts and formed rivers through the areas of flow. Grande ronde and wanapum basalt was created by fissures about 17-15 million years ago and made up about 85% of the flow.
When the layers of the Earth move it causes the tectonic plates (aka: plate tectonics) to move which causes the Alaskan Way Viaduct to collapse. The layers of the Earth are the inner core, outer core, mesosphere, asthenosphere, upper rigid mantle, oceanic crust, and the continental crust. The Density Column lab showed how things can have different densities like the layers of the Earth. It also showed how things that are most dense stay more towards the bottom and least dense stuff stays more towards the top. The Density
However, it 's not only just because of man-made reasons. The coastal marshes disappearing can also be affected by natural causes. Sediment is being deposited into a river delta increasing the weight, which causes the entire area to sink (p. 11). Depositing may sound like a positive cause, but however if the course of the sediment changes then no new sediment will continue to be deposited. Another natural cause is oceans and hurricanes.
These winds are often the worst kind of destruction that surrounding land can suffer from. When these winds are active, the surrounding dirt and rock will carry with the winds and possibly increase water levels extraordinarily(Lassieur 3). These loose pieces of rock and dirt could also act as a sort of pollutant of the air. It could also blur the vision distance that you could see. Another reason for a
• The Rodinia broke apart into two different continents. • The mass that would eventually become modern Africa, Australia, South America, Antarctica and parts of Asia was called Gondwana, and it was located near the South Pole. • Laurentia would break up to become North America and much of Europe and it was located closer to the equator. Climate • The Earth was generally cold during the early Cambrian. • There were likely polar ice caps and a series of glaciations, as the planet was still recovering from an earlier Snowball
The water carried the debris through the Sacramento Valley, the Delta, and the San Francisco Bay. Rivers, clogged with sediment, would overflow into the floodplains of the lowland. Floods were destructive for the environment and for residents especially in the Central Valley. Recognizing the importance of managing the water levels, residents along the river attempted to build levees. These levees proved ineffective in solving the flooding problem.