The most abundant source of sediment is the terrigenous material. The biogenous sediment is next, but it takes a thousand years to get about 1 centimeter of this material on the floor of the ocean. Hydrogenous and cosmogenous sediments are much less common. The hydrogenous sediments may be from manganese and other salts that don't dissolve well in certain types of water. Cosmogenous sediments come from asteroids or possibly comet remains.
THE CONTINENTS There are seven continents now, these are considered the major continuous landmasses around earth. These are permanent as far as we are concerned but were not very permanent in the past. You’ve studied 7 continents, but Europe and Asia are often combined to form Eurasia when it comes to geology. Australia is part of a larger region of islands collectively called Oceania, which includes the Pacific Islands. About 29 percent of the earth is covered with the continents. There is more continental earth above the equator than below it. Australia is confusing; it is a big island and a small continent, at least 4 times bigger than Greenland. Greenland is our largest island, part of North America. Continental crust is different from oceanic crust. It has more granite in it that contains a lot of aluminum silicate material. Oceanic crust is mostly basalt or hardened lava-like material. As mentioned, the continental crust is less dense overall and is older than the crust in the oceans. Expect the crust in the continents to be about 40 kilometers thick compared to only 6 kilometers thick in the ocean depths. The lithosphere is divided into plates that began much smaller. The continents are the older centers of these plates. Most plate boundaries are not near the edges of the continents themselves. The study of plate tectonics is how these plates move, shift, and subduct over time. All continents have flattened areas and mountainous ones. Shields are a major part of Africa but not as much as you'll find in Asia, which is more mountainous. Each continent has its own unique climate that affects everything else about it.
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