Grand Canyon Rocks “Those who write about the Canyon generally begin by saying that it is indescribable; then they undertake to describe it.” Joseph Wood Krutch

Grand Canyon: Rock Cycle Igneous Metamorphic Sedimentary Igneous rocks were the first rocks to form on Earth. They form from molten Earth materials. The crust is thin, varying from less than 10 km under the sea to over 50 km where there are massive mountains. Under the crust is a huge mass of rock called the mantle. Earth’s mantle is about 4200 km deep. Both the crust and mantle are solid rock.

Grand Canyon: Rock Cycle The crust and the uppermost region of the mantle make up the lithosphere, the dynamic surface of our planet. A localized mass of molten rock in the mantle or crust is called magma if it stays below the Earth’s surface. The same molten rock is called lava if it makes its way through the crust and flows out on the surface. When magma or lava cool, they crystallize to form igneous rock.

Grand Canyon: Rock Cycle Igneous rocks are identified by their composition (mineral content) and texture (the size of crystals they contain). The types of minerals that form depend on the starting composition of the magma or lava. Intrusive igneous rocks form from magma that intrudes into Earth’s crust but does not get to the surface. It cools and crystallizes slowly below the Earth’s surface.

Grand Canyon: Rock Cycle Extrusive igneous rock: basalt, rhyolite, obsidian, and pumice. Molten rocks that breaks through Earth’s crust is called lava. Lava cools quickly when it is subjected to cooler surface and temperatures and forms extrusive igneous rocks.

Grand Canyon: Rock Cycle Metamorphic rocks are changed rocks. In the past they may have been igneous, sedimentary, or even other forms of metamorphic rocks. The source rock changes because of heat and pressure, usually associated with the uplift of mountain building.

Grand Canyon: Rock Cycle Metamorphic rocks can be recognized by certain features that appear during metamorphism. Foliation: Crystallinity: Mineral Composition:

Grand Canyon: Rock Cycle Foliation: Mineral crystals flatten during metamorphism, arranging themselves along a plane.

Grand Canyon: Rock Cycle Crystallinity: Rocks changed by metamorphism might exhibit randomly arranged, coarse crystals that are fused together.

Grand Canyon: Rock Cycle Mineral Composition: Certain minerals are more commonly found in metamorphic rocks. (garnet, kyanite, pyrite, and brucite).

Grand Canyon: Rock Cycle The transformations that change one type of rock to another are commonly known as the rock cycle. The processes, erosion, melting, alteration by heat and pressure, are the keys to the transformation that define the rock cycle.

Grand Canyon: Rock Cycle The oldest known rocks on Earth come from the Mackenzie District of Canada’s Northwest Territories. They have been dated at 4 billion years old. To the best of our knowledge, the entire original surface of Earth has been recycled. Scientists have not been able to find even the tiny scrap of the original surface.

Grand Canyon Rock Cycle Lithosphere outer zone of Earth made of crust and the outermost part of the mantle. Mantle Crust hot, connecting molten rock. solid outer shell of solid rock plates. Outer Core Inner Core solid iron and nickel. molten iron and nickel.

Grand Canyon Rock Cycle Igneous Metamorphic Sedimentary

Grand Canyon Rock Cycle Rock formation: Clay * Shale @*# Slate # Schist # Gneiss # * Pressure @ deep underground # high temperature that “cooks” the rock. I S M

Grand Canyon Rock Cycle Rock Identification A Rock Identification B Rock Rock type Description Properties Number and name (fizz?) Textbook: pgs 42-46.