What is the driving mechanism of plate motion?
Plate Tectonics Driving Mechanism The forces that drive the motion of plates are assumed to be associated with the Earth's internal heat and involve flow of material in the asthenosphere. Various mechanisms have been proposed: * Convection Cells - Thought to be primary driving force for plate motion. Unequal heat distribution in the mantle may produce convection cells below the lithosphere. Hot material rises (correlates to spreading center), spreads laterally, cools and sinks deeper into the mantle to be reheated. Two convection cell models: 1. Shallow Convection Cell Model - Convection cells are restricted to the asthenosphere. Difficult to explain the source of heat for convection and the reason convection is restricted to the asthenosphere. 2. Deep Convection Cell Model - Entire mantle is involved in convection. Outer mantle is source of heat. Problem explaining how convection involved both the asthenosphere and lower mantle and how heat is transferred from the outer core to the mantle. * Mantle Plumes (not in book) - Hot spots, or plumes, of hot rising mantle material are known to exist around the world. Hot spots occur primarily at spreading centers (black smokers), although a few occur in the centers of oceanic plates and result in the formation of volcanic island chains. Hot plume upwarps overlying lithosphere which cracks and moves laterally away from the plume. Downward flow of the mantle must occur somewhere to balance the upward flow in the plumes. * Push-Pull Model - Lithospheric plates are pushed apart at hot spreading centers. Cold lithospheric plates are dense and tend to sink into the mantle, pulling the rest of the plate with it. Each part of the model can operate independently and are gravity driven. * Expanding Earth (not in book) - Model holds that the Earth has expanded through its history, so that overall new crust is being created at spreading centers. Has few supporters. Would require a 50% increase in the volume of the Earth over the last 200 million years.
Which is more correct: the theory of plate tectonics or the theory of continental drift? According to evidence, what actually did happen 200+ million years ago and how does it support each theory?
Continental drift is the description of how the continents have moved around over time. Plate tectonics is the explanation of why they do that. As currently stated, they should be equally correct, and simply complement each other.200+ million years ago the Earth happened to have most of its continental mass in a single body (Pangaea). This, by the way, was probably not a unique phenomenon, but simply one that occasionally repeats, as the continents wander around the Earth (to be discussed further below).At that time, forces (plate tectonics) generated in the mantle began to break up that ‘super-continent’, so that the Americas split off from Africa and Eurasia, and various pieces of the latter began to drift around relative to each other; so that since then, the Atlantic has been created by a spreading plate boundary in its center. Over a long period of time, the Americas will continue to drift westward relative to the others, and in a very long time (another 2 or 3 hundred million years, will crash into the eastern side of the Eurasian continent, forming another super-continent. This has happened before (about 450 million years ago, when the Appalachians and Alps were formed by the formation of Pangaea, and probably another 4 or 5 hundred million years before that — but the further back in time you go, the harder it is to find evidence of earlier collisions and breakups because of the erosion and weathering during that interval, and the effects of repeated collisions and breakups).
Is subduction the driving mechanism of plate motion on this expanding Earth?
Expanding Earth?Sorry sweetheart, but the Earth isn’t expanding. Its diameter is as stable as one could expect for something extant in a cosmos where change is the only constant.Subduction is the mechanism whereby the Earth’s tectonic plates are pulled down into the Mantle, turned back into magma, and recycled. Subduction zones are often termed “plate destruction margins”. For example, the reason Japan gets earthquakes is that its islands exist right on top of one such margin, where friction energy generated as the tectonic plates involved grind past each other, is released in the form of ground movement.The other type of plate margin, the creative margin, is, as its name suggests, the one that physically builds and widens the involved tectonic plates. For example, Iceland, which sits directly atop the creative plate margin known as the mid-Atlantic rift, grows by several inches every year thanks to the margin’s continual release of lava, which forms fresh terrain.It was in the 1960s that Plate Tectonics became an accepted scientific fact; before then, some scientists did believe that the Earth was getting bigger. (Otherwise they had no way to account for the fact that the North Atlantic is growing by the same several inches as Iceland.) But it isn’t: the two types of plate margins, creative and destructive, can be said in a way to maintain between them a balance, so that there is always the same amount (give or take) of total planetary surface.The science is out there on the internet and has been proven for a lot longer than I’ve been alive. The last time the Earth expanded, it was a planetisimal in the early days of the Solar System, roughly 4.53 billion years ago.Answer sources: my A-level in Geology.
What is the driving mechanism of plate tectonics?
The answer that your science teacher is looking for is probably "mantle convection"... But if you really want to impress your teacher, you should know that that answer is actually incorrect. Plates do not ride along on top of convection cells in the mantle like a conveyor belt. It's an outdated concept. That's what Earth scientists used to believe, but now they understand that even though convection does happen in the mantle, the effect of mantle convection on the movement of plates is probably too minor to be able to drive plate tectonics. The true answer is not "mantle convection,"... but instead, it is a force called "slab pull!" Slab pull results from the sinking of subducted lithospheric plates at subduction zones. The immense weight of the sinking plate pulls down the rest of the plate as well, causing the whole plate to move at the surface. There are other forces moving plates as well, but slab pull is the main one. ... Impress the teacher and the whole class by mentioning "slab pull!" This is a relatively new idea, so only scientists who study the Earth know about it. Don't be surprised if the uneducated masses still think that the answer is mantle convection. (If anyone tells you that slab pull is not the answer, just direct them to the references that I have cited below.) ...
What do many geologists think is the driving force of plate tectonics? explain?
In the late 50s and early 60s ocean research vessels were trying to map the deeps of the oceans because of deep diving submarines and discovered curious magnetic bands that appeared to spread out from a central point. That led to the discovery of spreading ridges and then the geologists were able to see just how plate techtonics worked!
Explain how seafloor spreading provides a mechanism for continental drift.?
Six questions on geology? Why didn't you take a class in home economics instead? You know, it wouldn't hurt to open that textbook and LEARN something. So which McDonald's do you plan on working at when you grow up?
How did continental drift lead to plate tectonics?
By the shape of the continents, particularly Africa and South America, it appeared both used to be connected. They drifted apart. This helped lead to the theory of continental drift which was later used in the more specific theory of plate tectonics. Plate tectonics provided the mechanism. Continental drift was more of an observation.
Could you describe the theory of plate tectonics and how it explains the presence of fossils from the same plants and animals in locations separated by great distances and large bodies of water?
Think of the Earth as a cracked hardboiled egg. The plates are joined but like the shell can be pulled apart or one piece of shell pushed over another.Organisms that existed when the plates were joined can have their bones preserved as fossils. When the continents separate the fossils eventually have an ocean between them. A nice example of the mobile continents and fossil record is in this picture.The rifting and seafloor spreading that pull and push plates apart are also responsible for causing plate collisions. These zones and sutures would be easier to visualize if the oceans were removed.In order to fully describe the mechanism of plate tectonics could not be done in this venue. The link provides a serviceable explanation of plate tectonics principles. The Theory of Plate Tectonics