The document provides information about rock formation and classification. It defines igneous, sedimentary and metamorphic rocks. Igneous rocks form from cooling magma, either below the surface (intrusive) or above (extrusive). Sedimentary rocks form through compaction and cementation of sediments. Metamorphic rocks form from changes to existing rocks through heat, pressure and fluids. Rocks are classified based on texture, composition and formation processes. The rock cycle illustrates how rocks continuously change between the three main types through various natural processes.

1. ROCK FORMATION Multiple Choice Identify the choice that best completes the statement or answers the question.

19. In some metamorphic rocks, layering does not occur. The mineral grains grow and rearrange, but they don’t form layers. This process produces a nonfoliated texture.

67. Extrusive Rocks Extrusive igneous rocks are formed as lava cools on the surface of Earth. When lava flows on the surface, it is exposed to air and water, and cools quickly under these conditions.

112. 35. Obsidian

114. A. IGNEOUS

115. 36. Gneiss

117. B. METAMORPHIC

118. 37. Slate

120. B. METAMORPHIC

121. 38. Limestone

123. C. SEDIMENTARY

125. Andesitic Rocks Andesitic igneous rocks have mineral compositions between those of basaltic and granitic rocks. Granitic rocks contains lots of silica but lesser amounts of iron and magnesium Basaltic rocks form from magma that is rich in iron and magnesium and poor in silica

134. 44. Use the information about igneous rocks a-d to classify each one as intrusive or extrusive and basaltic or granitic. Fill in the chart with a,b,c,d Rock a- dark colored large grains Rock b- large crystals, high percentage of silica Rock c- fine grained texture, light colored Rock d- from Hawaiian volcano area no visible crystals 4 3 granitic 2 1 basaltic intrusive extrusive

136. 4 B 3 C granitic 2 A 1 D basaltic intrusive extrusive

137. 45. In a concept map, would you list basaltic lava under high silica content or low silica content.

139. Low silica content

159. true

163. 54. Nonfoliated rocks have very narrow layering.

171. true