The Rock Cycle. The Rock Cycle: There are many different things that can happen to a rock that will change it into a different type of rock. Ex. Weathering/erosion/compaction/cementation Melting/cooling Heat/pressure. Igneous Rocks. Igneous rocks are created when
Igneousrocks are created when
magma from inside the Earth
cools and hardens. There are
two kinds of igneous rocks and
they look quite different:
Intrusive rocks cool and harden underground very slowly. This creates large, easy to see mineral grains or crystals.
Granite is the most common type of intrusive igneous rock.
Extrusive rocks cool above ground much quicker. This prevents mineral grains or crystals from forming.
This happens on the side of volcanoes and creates obsidian.
Or on the ocean floor near mid ocean ridges. This creates basalt.
Sedimentary rocks are formed when rocks are weathered and eroded by wind, water and glaciers. These sediments (gravel all the way down to sand) get transported (mostly by water) untilthey settle to the bottom of the rivers, lakes, and oceans. This happens year after year, layer after layer. Those layers get pressed and compacted together. Eventually the water dries up and they become a new rock.
When sedimentary or igneous rocks are buried deep underground they are exposed to heat from magma below and pressure from the weight of the ground above. This heat and pressure will change the sedimentary or igneous rock into a metamorphic rock.
Shale (sedimentary) . . . . . . .to . . . . . . . Slate (metamorphic)
Sandstone (sedimentary) . . . . . to . . . . . Quartzite (metamorphic)
Limestone (sedimentary) . . . . . . . to . . . . . . . .Marble (metamorphic)
Granite (igneous) . . . . . . . to . . . . . . Gneiss (metamorphic)