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.
Wegeners ideas were proved even further, increasing our knowledge of tectonic events. Sea floor spreading shows that rock is being both created and destroyed. In the 1950s and 1960s, ages of the ocean floor were measured. The surveys suggested that very young rocks, ageing less than 1 million years old, are found near ridges and older rocks, ageing over 200 million years, are found near the continents. Evidence of sea floor spreading can be found in the Atlantic, where it is believed that the North American and Eurasian plates are moving apart at a constructive plate margin.
What is "summit deflation"? (page 94, para 2 to page 95) Summit deflation, which is measured by tilt meters in parts per million, is when the slope of a volcano changes usually relatively prior to an eruption. 4. How does Kilauea's magma move upward
Whereas Eyjafjallajokull is in Iceland, an MEDC. The initial eruption of Eyjafjallajokull lasted from 20th March- 23rd June, however the eruption was declared officially over in October 2010. It is located on a spreading ridge, where convection currents are driving apart the North American plate (moving west) and the Eurasian plate (moving east) along a divergent plate boundary. This is creating the Mid Atlantic ridge, along which the age of the rocks either side of the ridge and the palaeomagnetism have been used as evidence of the plate tectonics theory. Both eruptions caused disruption to aviation, particularly Eyjafjallajokull which was a relatively small eruption.
a. strain buildup only b. location of foci c. magnitude of P-waves [pic] d. reoccurrence rates of earthquakes in an area and the rate of strain buildup 2. What are most earthquakes associated with? a. rift valleys b. mid-ocean ridges c. divergent plate boundaries [pic] d. plate boundaries 3. At what point in the graph would a rock be permanently deformed? [pic] a. at the start of the stress [pic] b. past
There were also the same fossilised pollen species and rock sediments on these coastlines. Wegener’s ideas were further proved and built upon by other ‘geographers’ which has increased our understanding of tectonics events today. Sea floor spreading was discovered which showed that rock is always being created and destroyed; this lead us to believe in the existence of plates and plate boundaries across the lithosphere. Sea floor spreading has been shown to exist in the Atlantic Ocean where the theory is that the Eurasian and North American plates are moving apart, at what is called a constructive plate boundary. This is where magma rises through a rift and cools
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).
Geologically, Aruba is more complex. The geological formation of Aruba’s geography is composed of three major rock groups; Igneous, metamorphic and sedimentary. To the reader who just looks at the textbook, this means that Aruba (the Island) was there long before the late 15th century when the Spanish first came here. Actually, Aruba was formed from the process of volcanism some 90-95 million years ago. The Island of Aruba is the result of lava hardening from a volcano that occurred almost 100 million years ago underwater.
("Geology," 2008) It resulted in the folding of the area and shortened the north/south length of the area by about 8.7 miles. (Jaritz, 2008) “Kata Tjuta, near the end line of this bulldozing movement, was tilted only by15 degrees. But Uluru was rotated and almost tipped over at a steep angle close to 90 degrees.” (Jaritz, 2008) The near vertical sediment layers evident within the formation of Ayers Rock are due to this major earth movement. The continuing formation of Ayers Rock occurred slowly after the Alice Springs Orogeny. About 65 million year ago, the climate of the area had become extremely wet, and this brought river sand, swamp deposits, and small traces of coal to the area.
Scientists have since seen these patterns as precursory to eruptions at many other volcanoes, including the 2004-2008 eruption of Mount St. Helens. At Mount St. Helens the value of an extensive system of seismic sensors has greatly improved our ability to determine the location and depth of earthquakes, and our ability to understand the physics of magma systems underground. The lack of short-term seismic or other geophysical indications in the hours and days prior to the May 18, 1980, debris avalanche, as well as prior to many short discrete explosions both before and after May 18, underscores that fact that scientists and public officials will not always have warning sufficient to issue short-term predictions of impending eruptive activity. Today, seismic