Page 41 - Curriculum Visions Dynamic Book

There is much evidence for the rock cycle. We can see volcanoes adding new material to the crust as ash and lava, and we can see rivers, wind, ice, and waves carrying eroded rock to the oceans, where it is deposited.
The deposited material settles in layers and gradually compresses under the weight of more sediment to make layers of rock. This kind of rock is called sedimentary.
Much of the sediment accumulates around the edges of continents. Since they are also often the boundaries of plates, there is also a mechanism for scraping the sedimentary rocks off the ocean floor and making them into land (see pages 32–34).
Thus, from being deep under the ocean, the rocks eventually find themselves forced up onto the crust, usually as parts of new mountain systems.
Sometimes the fact that rocks are sedimentary is easy to see because they are still in level layers. But more often they have been contorted, so they now make broad arches or dips or even stand on edge.
ash Fragments of lava that have cooled and solidified between when they leave a volcano and when they fall to the surface.
lava Hot, melted rock from a volcano. magma Hot, melted rock inside the Earth
that, when cooled, forms igneous rock.
sediment Any particles of material that settle out, usually in layers, from a moving fluid such as air or water.
sedimentary Rocks deposited in layers.
water cycle The continuous cycling of water, as vapor, liquid, and solid, between the oceans, the atmosphere, and the land.
 These Grand Canyon cliffs show
a typical staircase of layers that are the signature of sedimentary rock. In this case they have not been buckled. Sedimentary rock of this kind is produced on no other planet.
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