Chapter 3 is about Earth’s structure and plate tectonics. Earth’s interior is consists of four layers inner and outer core, mantle, and Earth’s crust. Each layer is thicker than the layer above. Millions of years ago Earth was as one continent, but eventually the continents have spread out from each other. Continents are floating in the ocean and constantly moving towards or away from one another. The movement of continents is due to plate tectonics about 1-15 centimeters a year. Different plates move at a different rate. There are about a dozen of tectonic plates on the Earth. The plates have converged, diverged, and slipped past one another since Earth’s crust first solidified and cooled, driven by slow, heat-generated currents rising and …show more content…
The continents are old but the ocean floors are young do to volcanic activity from the ocean ridges. It is was difficult and complicated process for oceanographers and geologists to find about the shape of seabed. Seafloor features result from a combination of tectonic activity and the processes of erosion and deposition. Guyots are the flat-toped seamounts which were formed millions of years ago in the mid-ocean ridge crest due to volcanic eruptions. Magma from asthenosphere progressively shaped the seamount. Some seamounts were formed above the sea-level. Eventually, ocean floor moved and the seamounts were carried away as well, away from its source of lava and became non-active volcano or a seamount. This activity formed a chain of seamounts, tablemounts and islands. Some seamounts have its top above the sea-level. Seamounts with tops (islands) above the sea-level had their tops eroded by waves and wind, eventually, wearing the top down and thus formed a flat top. In millions of years, these flat-toped mounts (guyots) were submerged beneath the ocean and away from the mid-ocean …show more content…
There are two kinds of continental margins: passive and active. Passive and active continental margins are different in structure and have different features. Passive continental margins are near diverging plates and therefore, they tend to have minor earthquake or volcanic activity. Passive continental plates are also called Atlantic-type margins. Passive margins have broad continental shelves that reach about 350 kilometers or 220 miles in width and end at a depth of about 140 meters or 460 feet below the sea-level. The broad shelf extends far from shore in a gentle incline, typically 1.7 meters per kilometer that is 0.1°, or about 9 feet per mile followed by a steeper drop-off or a shelf break about 140 meters or 460 feet. Then begins a continental rise that reaches for about 300 miles farther into a deep basin. The features of the deep ocean basins include: oceanic ridges, abyssal plains, deep trenches, chains of volcanic
15. The pictures above show how the continents on Earth’s surface have changed position over a very long period of time. What explains this change? (S6E5e, f)
Earthquakes are a natural part of the Earth’s evolution. Scientific evidence leads many geologists to believe that all of the land on Earth was at one point in time connected. Because of plate tectonic movements or earthquakes, continental drift occurred separating the one massive piece of land in to the seven major continents today. Further evidence supports this theory, starting with the Mid-Atlantic ridge, a large mass of plate tectonics, which are increasing the size of the Atlantic Ocean while shrinking the Pacific. Some scientists believe that the major plate moveme...
could be used to explain and illustrate that previous theories were not entirely correct (Merali and Skinner, 2009, p.253). Through the analyzation of arrival times of these waves, Oldham had drawn an conclusion that p waves and s waves react differently in terms of being refracted, reflected or absorbed depending on the state of the material as shown in Figure 1.(Tarbuck, Lutgens, Tasa, 2013, p.143). Oldham had developed this theory of the Earth not being the same state due to these effects of seismic discontinuity which are shown in Figure 1., consisting of refraction, reflection and absorption. The changes that are displayed from this idea are; the speed of the waves due to a refraction occu...
The earth is split into four layers, inner and outer core, the mantle and crust. The top of the mantle and crust make up what is like the skin of our earth (see source 2). The skin is split up like a puzzle and we call these puzzle pieces’ tectonic plates (see source 1). These plates are constantly moving and the plate boundaries (edges of the plates) move and slide past one another. Sometimes as the plates move the plate boundaries become stuck. Pressure builds up in the stuck area over time and eventually breaks. This is why earthquakes occur due to the sudden movement of the plate sliding and breaking creating a fault line to go off. The fault line is the line on which the
...lision, sea levels were lower. The poles began to gain ice caps. Due to all the ice, the sea levels dropped even more. With the sea levels decreasing, there was more land between continents for animals to travel across. Due to the continually cooling climates, the earth entered an Ice Age. The lower sea levels and new mountain ranges contributed to it. There were a lot more ice caps than there are today.
7. Refer to Figure 22-6. What name is given to the core of the modern-day North American continent that formed in the Proterozoic?
The rate of seafloor spreading was minimal during the Ordovician Period but thanks to high oceanic ridges, the seafloor became elevated and many parts of the continents were flooded. Shallow seas within the continents were thus formed. Sea levels fluctuated constantly maybe due to the rates of plate motion, ice caps, etc. The major tectonic plates were moving during this period so volcanism was extensive, peaking twice during the early Paleozoic Era. Mountain building belts were created wherever plates converged as well.
The theory of plate tectonics, only recently introduced to the world, transforms the thought that the earth has been the same since its beginning. The theory alters the view of the average person almost in the way that Columbus showed the world was round. The theory of plate tectonics was developed from the theories of continental drift and sea-floor spreading and states that the earth’s surface is divided into several large plates, which are constantly in motion.
Primary coasts are divided into two categories: submergent and emergent coasts. Submergent coastlines result from a general sea-level rise and crustal subsidence. Most of the eastern United States has submergent coastlines. One example is the Chesapeake Bay. Emergent coastlines result from the land being lifted, either by tectonic activity or rebound from the weight of heavy glaciers, which exposes the former sea bottom bit by bit forming continuously new shoreline.
Since the beginning of human kind there has been a cloud of wonder of how our planet was formed. Scientist interested in this field through out the years have developed many different theories to how our planet came about. Before the Twentieth Century, scientists and geologists thought that mountain structures were due to the massive tightening of the earth caused by the gradual cooling of molten rocks. In 1900, American scientist Joseph Le Conte, published an article in the Appleton's Popular Scientific Monthly. He described that the problem in understanding mountain building was establishing the cause of sideways pressure. It was not until 1910, that an American Geologist named F.B.Taylor, proposed the idea of a continental drift. Other scientists dismissed Taylor's idea, because there was just not enough proof. However, Taylor's idea was then backed up by a German scientist named Alfred Wegener. He proposed that the continents surrounding the Atlantic Ocean, Africa and South America fit together like a jigsaw puzzle. His broad range of studies enabled him to incorporate his theory of Plate Tectonics. Wegener, later in 1915 while in the German military published his idea that interpreted how his continental drift theory worked. He proposed that a huge landmass called Pangea, meaning ("all land") existed 200 million years ago. He furthered explained that this super continent began to drift apart very slowly throughout millions of years into what it looks like now. Wegener went on several expeditions through out his life to the continents of South America and Africa.
First you might need to know definition of tectonics. It is a theory in geology. The lithosphere of the Earth is divided into a small number of plates which float on and travel independently over the mantle and much of the Earth’s seismic activity occurs at the boundaries of these plates. That is the official definition of Plate tectonics. secondly, this plate covers many parts of continents. plate boundaries don’t go according to Continents boundaries, they make their own boundaries. The North American plat...
They are the earth’s crust; they move very slowly every year. As the tectonic plates slide over each other they cause earthquakes. Earthquakes produce various damaging effects this includes damage to structures of buildings, bridges and other standing formations which then...
Our Earth was formed 4.6 Billion years ago. This formation is partly due to the colliding of tectonic plates found under the Earth’s crust. These plates have greatly impacted the way in which the Earth’s outer layer looks and the type of terrain found across its vast surface. One example of these plates at work are volcanoes. Volcanoes are formed through the process of volcanism. This process occurs when “magma- a mixture of molten rock, suspended mineral grains, and dissolved gases formed in Earth 's interior — is forced to the surface.” (Reed,2013) The concept of isostacy is the “ideal theoretical balance of all portions of Earth’s lithosphere as though they were floating on the denser underlying layer is isostacy.” (Reed, 2013) When considering
Earth system refers to the earths interacting physical, biological, and chemical processes. The system consists of land, oceans, atmosphere and poles. The earth system has four spheres, including the geosphere, the hydrosphere, the atmosphere, and the biosphere. The geosphere refers to the solid parts of the earth system, including earth’s rocky crust, mantle, and the metallic core. Within the geosphere is the lithosphere, which only refers to the uppermost layers of solid earth. The uppermost layers of solid earth are the oceanic and continental crust rocks. Just below the crust is the mantle, which is composed mostly of magnesium and iron silicate minerals. The mantle accounts for about 2/3 of the
Due to the fact that rocks are composed of high intensity of elastic and brittle material, they therefore store considerable amount of strain energy that results from elasticity, during the action of plate tectonic. The brittleness leads to development of concurrent cracks on the rocks as a result of plate’s action.