He believed that all of the continents were once joined together, forming a super-continent called Pangaea. These plates are thought to float on the underlying semi-molten asthenosphere and are moved by convection currents that derive their heat from the earth's crust. It states that this process isi continous and forms new land along the boundaries where the plates move apart - known as constructive margins - and destroys older crust where the plates are moving together - destructive margins. Later evidence also supported this theory - fossilised remains of a dinosaur, the mesosaurus, were discovered on the coasts of Brazil and Gabon. Wegeners ideas were proved even further, increasing our knowledge of tectonic events.
An inward tilt during eruption is much steeper than that of re-inflation. 6. What are "vesicles"? (page 99, para 1) Tiny bubbles that have gas trapped in them after the solidifying of the magma after eruption. 7.
He suggested that at the centre of oceans, molten material would rise from the Earth’s mantle, causing new sea floor to be created, pushing the ocean floor. He also suggested that there were ocean trenches where old sea floor would then go back into the mantle, and molten. He found that these ocean trenches, the deepest parts of the ocean, were very near continental plates. Hess theorized that the action of the sea floor spreading caused continents to move apart and so this being evidence for continental drift, showing why it happened. The evidence of sea floor spreading was further supported by Vine and Drummond, who studied the magnetic pattern of the sea floor.
In this convergent boundary, the denser Nazca Plate is being subducted beneath the less dense continental lithosphere of the South American tectonic plate. As the plate descends it causes earthquakes in the Benioff zone, and volcanoes occur here because of melting of the plate in the asthenosphere. The southern end of the plate dips at a steep angle, while the northern end may be experiencing flat-slab subduction (in which the oceanic plate slides below the continental plate at a very low angle). A low angle of subduction may explain the relative lack of volcanic activity in the Northern part of Chile, compared to the extremely active southern volcanic mountains. Whereas Eyjafjallajokull is in Iceland, an MEDC.
The deepest part of the ocean is located in a trench south of Japan and north of Papua New Guinea c. The depth of the trench exceeds the height of Mount Everest. d. The depth of the trench is estimated at 5000 meters. e. The trench is called the Mariana Trench. 9. The nebular hypothesis suggest that: a. all bodies in the solar system formed from an enormous gas cloud.
Tension [pic] d. Compression 6. What is Earth's core composed of? [pic] a. hydrogen and iron b. magnesium and silicon [pic] c. iron and nickel d. nickel and silicon 7. A large ocean wave that is generated by vertical motions of the seafloor during an earthquake is called a(n) __________. a. upwelling current b. seiche [pic] c. tsunami d. tidal range 8.
Due to high temperatures in the mantle of around 3000 degrees centigrade, this oceanic crusts melts and then rises due to the convection currents in the aesthenosphere . As it joins with trapped seawater and sediment, it melts the overlying continental crust, and the magma plumes rise to the surface. They contain more silica so are more viscous, which plugs up the volcano, meaning pressure build up. This is why these volcanoes are so explosive. Another type of plate boundary are constructive, which is the margin between two diverging plates where new magma
Mt Kosciusko Field Trip Report Geological History of the Australian Alps The geological history of the Australian Alps starts when the majority of east Australia was submerged underwater at around 800 million years ago. At this time there were large sediment layers that covered the sea floor. By around 450 million years ago, the earth began to move underneath the continental plate causing uplifting and folding (Australian Alps National Parks, 2010, Geology and geomorphology of the alpine landscape para.6). Magma rose up through the layers at temperatures reaching up to 1000°C. The magma that reached the sea bed due to weakness in the crust cooled quickly and formed a layer of basalt above the sediments (see diagram 1).
Where is the park located and what are its' dimensions? The base of the Cascade Range was constructed as the Earth's crust folded and uplifted, pushing the seas westward. Molten rock pushed toward the surface, creating both violent eruptions and forcing an incredible amount of lava upward through enormous cracks. Within the past 750,000 years these explosive eruptions built a string of volcanoes on this plateau base. This Cascade Range of volcanoes extends from Canada's Mount Garibaldi to Lassen Peak in northern California.
There is a convergent boundary on the west side of the United States. At a convergent boundary, two plates collide, and the denser plate is subducted. Volcanoes and earthquakes are common as a result of pressure and friction. There is also a transform boundary forming the San Andreas Fault which is between an oceanic plate subducting under a continental plate. 3.