Science - Need help with Plate Tectonics! (1 Viewer)

[cs01001]

I am currently trying to do some revision for the Science trial, I was reading over my Plate Tectonics note, and something just didn't make sense to me...

Can someone please explain to me what "Continental & Oceanic Crusts" are? and also I am not quite sure what "Ocean and Ridges" are".

Please help me out!

Thanks~~

 

[agentcheeseball]

I hope that this is of help.

You have two types of crusts the one continental and the one oceanic. The continental is if the crust is part of the plate that is land while the oceanic is the part that is under the ocean on the sea floor.

Now you can get ocean ridges and sea floor spreading. Sea floor spreading is when there are two oceanic plates which drift apart under the sea and magma rises up and is cooled to fill the gap between the plates. This cools and becomes part of the oceanic plates and forms sea floor spreading from memory. You can also have when the two oceanic crusts meet and are of similar weight and so instead compress upon one another folding the plates up agaisnt each other creating a ridge.

You can also have submerging of the two plates when the continental plate pushes an oceanic plate underneath it and the oceanic plate melts into magma.

 

[z600]

Continental Plates are a piece(s) of crust with a piece of land on it. Eg, The Indian-Australian Plate (not technocal but idiotproof)
Oceanic Plates are piece(s) of crust with the ocean above it.

Ocean ridges are the result of something call seafloor spreading. This is when two oceanic plates moving away from each other<-----THis is caused by rising magma. Magma rises and cools in the ocean thus creating new sea floor. This makes new crust as other crust are destoyed as a result of subduction.

To be technical, i think you should use plates rather than crust. Plates are pieces that makes up the Earth's crust.

Man i hate the rocks topic and the evolution topic.....

I am not too good with geology, if i am wrong anywhere, feel free to correct it.

 

[Zephyrio]

Here are my notes on it. I hope they help

Earth Plates

• In 1915, a German scientist, Alfred Wegener, suggested that Africa, South America, Australia, Antarctica and India were joined about 200 million years ago.
• This super continent, called Gondwana, gradually broke apart and the continents separated.
• Wegener’s hypothesis was called Continental Drift.
• The theory of continental drift proposes that about 250 million years ago, the present-day continents were all joined together in one supercontinent called Pangaea. They separated into a northern supercontinent called Laurasia, and a southern supercontinent called Gondwanaland about 180 million years ago and have, since then, have continued moving apart.
• Evidence to support Wegener’s ideas include:
  • Similar limestone deposits are found in Australia, Antarctica and southern Africa.

[FONT=&quot]o[FONT=&quot] [/FONT][/FONT]Fossils of an ancient plant called Glosspteris are widespread in all five continents and absent from Europe, Asia and North America.
[FONT=&quot]o[FONT=&quot] [/FONT][/FONT]Fossils of Mesosaurus, a crocodile-like reptile are found in Southern Africa and in South America.
§[FONT=&quot] [/FONT]In the middle of the ocean, a mountain range higher than any on the continents was mapped. This was called the Mid-Atlantic Ridge and it was later found to run from the Arctic, right down the middle of the Atlantic Ocean near the Antarctic Circle in the south.

[FONT=&quot]At the Mid-Atlantic Ridge, new rocks are being made as hot material rises from the Earth’s mantle and pushes the older rocks away from the ridge line.

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• Scientists infer that the Earth’s crust is made of slowly moving plates which spread out from mid-oceanic ridges. Because the oceanic plates are heavier than the continental plates, they slide under them and melt into the asthenosphere.
• The idea that giant sections of plates of crustal rock move over the Earth’s surface became known as the theory of PLATE TECTONICS, a modification of the old Continental Drift hypothesis.

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