Table of Contents Chapter 4: Rocks Section 4.1: The Rock Cycle

The Rock Cycle 1 The Rock Cycle The rock cycle shows the three types of rock— igneous, metamorphic, and sedimentary—and the processes that form them. Click image to view movie.

Igneous Rocks 2 Magma Because (2) magma is less dense than surrounding solid rock, it is forced upward toward the surface. When magma reaches Earth’s surface and flows from volcanoes, it is called lava. The difference between magma and lava is location: magma underground and lava on surface

Texture (3) Texture refers to the size of a rocks mineral grains. (4) coarse—large mineral grains fine---small mineral grains glassy—no mineral grains

Igneous Rocks 2

Question 5 Extrusive Intrusive Formed from lava Formed from magma Formed on the surface Cools quickly Fine or glassy texture Small grains or no grains EX: rhyolite Pumice basalt obsidian scoria Intrusive Formed from magma Formed underground Cools slowly Coarse texture Large mineral grains EX: granite gabbro

Classifying Metamorphic Rocks 3 Classifying Metamorphic Rocks Heat, pressure, and hot fluids trigger the changes. Each resulting rock can be classified (7) according to its composition and texture.

Question 8 Foliated Has visible layers EX: gneiss slate schist Nonfoliated Does not have visible layers EX: marble quartzite

Question 9 Igneous to metamorphic Granite --- gneiss Basalt --- schist Sedimentary to metamorphic Shale --- slate Sandstone ---- quartzite Limestone --- marble Metamorphic to metamorphic Slate --- phyllite

Formation of Sedimentary Rocks 4 Formation of Sedimentary Rocks (11) Igneous rocks are the most common rocks on Earth, but because most of them exist below the surface you might not have seen too many of them. 75 percent of the rocks exposed at the surface are sedimentary rocks.

Formation of Sedimentary Rocks 4 Formation of Sedimentary Rocks Sediments come from (12) already-existing rocks that are weathered and eroded. Sedimentary rock forms when sediments are pressed and cemented together, or when minerals form from solutions.

Classifying Sedimentary Rocks 4 Classifying Sedimentary Rocks Like igneous and metamorphic rocks, sedimentary rocks are classified (13) by their composition and by the manner in which they formed.

Weathering and Erosion Sedimentary Rocks 4 Weathering and Erosion When rock is exposed to air, water, or ice, it breaks down chemically and mechanically. (14) weathering is the process which breaks rocks into smaller pieces. These pieces are classified by size. erosion is the movement of weathered material

Sedimentary Rocks 4 Compaction

Sedimentary Rocks 4 Cementation

(15) Detrital (Clastic) Chemical Formed from rock sediments on the surface Formed by compaction and cementation EX: Sandstone, shale conglomerate,breccia Chemical Formed by precipitation of minerals or evaporation of water. EX: Limestone

(15) Organic Formed from remains of living things Formed by compaction and cementation EX: coal, shell limestone