Tectonic Plates

In 1596- Abraham Ortelius took note that the coastlines of the continents seemed to be too fitting together. He initiated a theory that stated that the continents were probably joined at one point in time and were torn apart between Europe and Africa. In the year of 1912, Alfred Wegener stated that the continents were once joined in a supercontinent called Pangea.

II: Plate tectonics shows the features and movement of the Earth. The theory of plate tectonics says that the outer shell of the earth is broken down into pieces often called plates (Korenaga). These plates hover over the mantle creating movement (Marshak). With plate tectonics you can determine the earth’s features without actually seeing it.

The theory of plate tectonics states that the Earth’s lithosphere (top layer of the Earth’s crust) is split up into rigid sections called plates that are moving relative to one another as they move on top of the underlying semi-molten mantle. These plates are either continental, The North American Plate, or oceanic, The Nazca Plate.

Plate Tectonics is a scientific theory which study how the Earth’s plates are driven and shaped by geological forces to keep them in constant movement. The theory explains the present-day tectonic behavior of the Earth, particularly the global distribution of mountain building, earthquake activity, and volcanism in a series of linear belt. (Pitman, W.C., 2007)

The theory of the continental drift is that the continents have slowly drifted to their current location. Alfred Wegener believed that all the seven continents were once a supercontinent known as Pangea. A discovery that came from climate clues like glacial deposits in South America, Africa, Australia and India. Rock and fossils matching evidence found in South America and Africa.

The theory of Pangaea suggests that the continents were once stuck together into one huge continent. Eventually they started drifting into separated landmasses, which gave birth to the modern continents.

Plate tectonics is the scientific theory that attempts to explain the movements of the Earth's lithosphere that have formed the landscape features we see across the globe today” (Briney). Geology defines “plate” as a large slab of solid rock, and “tectonics” is part of the Greek root word for “to build.” Together the words define how the Earth’s surface is built up of moving plates. The theory of plate tectonics dictates that individual plates, broken down into large and small sections of rock, form Earth’s lithosphere. These fragmented bodies of rock move along each other atop the Earth’s liquid lower mantle to create the plate boundaries that have shaped Earth’s landscape. Plate tectonics originated from meteorologist Alfred Wegener’s theory, developed in the early 20th century. In 1912, he realized that the east coast of South America and the west coast of Africa appeared to piece together like a jigsaw puzzle. He further examined the globe and deduced that all of Earth’s continents could somehow be assembled together and proposed the idea that the continents had once been linked in a single supercontinent called Pangaea. To explain today’s position of the continents, Wegener theorized that they began to drift apart approximately 300 million years ago. This theory

Earth's plates and continents do not always just stay in one place. They shift, collide, and move apart, causing destruction in many different parts of the world. The movement of plates causes volcanic eruptions, changes in the oceans, and perhaps the most dangerous of all, earthquakes. Earthquakes may have the most devastating effects on people and cities.

The Plate Tectonic Theory developed in the late 1960’s, when people noticed how continents either side of the Atlantic Ocean seemed to almost fit together. Francis Bacon, an English Philosopher was aware of this as early as 1620. Topographical and geological evidence built up and allowed Alfred Wegener to publish a theory in 1912, suggesting that the continents were once all joined together in a supercontinent he called Pangaea. Wegener proposed that at some time, the land masses had drifted apart until they occupied their current positions on the globe. There was lots of evidence to support his theory including

The Earth is always changing because of plate tectonics. Plate tectonics describes the behavior of earth's out shell, with pieces bumping and grinding each other about. Most of the world's active volcanoes are located along or near the boundaries between shifting plates and are called plate-boundary volcanoes. The Hawaiian Islands are one of the best examples of an intra-plate volcanic chain. They are developed by the northwest-moving Pacific Plate passing over an inferred hot spot that inmates the magma generating and volcano-formation process. The Ring of Fire in parts of the Pacific Ocean contain many active volcanoes which Mt. St. Helens is a part of. The zone along plate boundaries are the most geologically active regions on Earth.

The breaking apart of this supercontinent was due to the movement of the Earth's Tectonic Plates. Tectonic Plates are large masses of the lithosphere or outer layer of the Earth's surface. The layers included in the Lithosphere are the Crust up to the upper layer of the Mantle. The Oceanic Crust is thinner and denser than the Continental Crust and can be found underneath the ocean. It is also more active than the Continental Crust that stretches 200 km below the Earth's surface. This crust drifts and moves either horizontally or vertically causing geological phenomenons such as earthquakes, volcanic eruptions, etc. The major tectonic plates are North American, Caribbean, South American, Scotia, Antarctic, Eurasian, Arabian, African, Indian, Philippine, Australian, Pacific, Juan de Fuca, Cocos, and Nazca. These plates move an estimate of 1 to 10 cm per year causing interaction at plate boundaries. When two plates are colliding or moving toward each other it is in Convergent boundaries. If these two plates are Oceanic Crusts, they are in Subduction zones wherein the denser plate in forced beneath the less dense plate and would eventually melt or destroy. On the other hand, when two plates move away from each other it is in Divergent boundaries. New crust material from molten magma formed below may fill the space between these plates or become ocean basins.

Tectonic plates never stop moving and continue to change the surface of the earth in present day. The movement of tectonic plates is the main reason for the formation of the Panama Isthmus with an arc of islands that eventually connected to create a link between North and South America. With the Panama Isthmus came many changes to the world. Animals were introduced to new areas. Fossil records help scientists understand what animals made their way across the land bridge into both Americas. The closing of the link between the Pacific and Atlantic oceans altered the environment and climate of the world. The world today would be very different if the isthmus had not formed; with tectonic plates in constant motion, the world will continue to change and be completely different in the future than it is today.

A German meteorologist and explorer Alfred Wegener put forth the theory of continental drift in the early 1900’s. Wegener pointed out that the earth’s continents looked as if they were all connected at one point in time. He also pointed out that some of earth’s features, including the long S-shaped mountain structure formed on the Atlantic seafloor, could fit snugly against the corresponding western seafloor of Europe and Africa (Sieh and LeVay 1998). Wegener proposed that all of the earth’s continents once formed one single landmass, which he named Pangaea or “all-land”. He concluded that Pangaea had broken up and separated due to the unidentifiable forces estimated 300 million years ago (Sieh and LeVay 1998). Geologists did not fully understand at the time that Earth’s continents could drift (Hazen 2012). After all, the continents do not float in the oceans. They are made from a solid material connecting to the mantle, a sphere of solid rock

The thicker sections fo the plates are the continents; the thinner parts make up the ocean beds. When two plates meet, the result is geologic upheaval on a vast scale. Such an encounter occurred about 20 million years ago in the region between North and South America. The Cocos Plate, a piece of the Pacific crust some 300 miles wide, moved eastward until it met the crustal plate underlying the Caribbean. The eastern edge of the Cocos Plate was driven beneath the western edge of the Caribbean Plate. As the Cocos Plate was forced downward, the friction, as well as the hear deep within the earth, liquefied its rock into magma, which found release by thrusting up in a chain of volcanoes. The volcanic islands that resulted formed a line of stepping-stones between the northern and southern

In general there are three types of boundary activity, the first in divergent this is where two plates are moving away from each other and therefore new land is being formed from the mantle underneath. The second is called subduction this occurs when two tectonic plates are moving towards each other - it is along these types of boundaries where mountain are generally found. The third and final type is called transform, this occurs when two plates are moving side by side and this is where earthquakes are normally