Mrs. Giblin Earth Science Ch. 3 Notes Rocks Mrs. Giblin Earth Science
A Rock is… any solid mass of mineral or mineral-like matter that occurs naturally.
3 Types of Rocks: Igneous – magma or lava cools and hardens. Sedimentary – sediments settle out of a fluid and become cemented together. Metamorphic – existing rocks are changed by heat and pressure.
Igneous Rocks Intrusive – cool beneath Earth’s surface. Extrusive – cool on the Earth’s surface. Texture: The longer the cooling time, the larger the crystal size. Coarse-grained-large crystals, cooled slowly Fine-grained-small crystals, cooled quickly Glassy-very small crystals, cool very quickly
Composition: Porphyritic-large crystals surrounded by fine-grained material. Granitic-quartz and feldspar rocks-light-colored. Basaltic-contain Mg and Fe-dark in color. Andesitic-in between granitic and basaltic. Ultramafic-almost entirely dark minerals. Felsic-light in color, low in density. Mafic-dark in color, higher in density.
SEDIMENTARY ROCKS
Deposition-dropping of particles Formation: Weathering-breaks down rocks Erosion-moves particles Deposition-dropping of particles Compaction-squeezes sediments together Cementation-dissolved minerals fill the spaces in between sediments.
Classification: Clastic-weathered bits of sediments are compacted together. size of particles used to group clastic rocks. Rounded particles-conglomerate Angular particles-breccia Chemical or Biochemical-dissolved minerals precipitate out of water and are cemented together. Water usually evaporates off. Special Features: Horizontal layering Fossils-animals, plants Trace fossils-tracks, footprints, mud cracks
CLASTIC ROCKS Breccia Conglomerate
0.2-0.006cm 0.006 –0.0004cm Sandstone Siltstone
CHEMICAL ROCKS Rock Salt Rock Gypsum
Limestone
Coal
FOSSILS
NYS Fossil- Eurypterid
Sedimentary Rocks in NYS Letchworth State Park Sandstone, Limestone, Shale
Watkins Glen Taughannock Falls Sandstone
Thatcher Park-Shale
Metamorphic Rocks
Formation: Formed by increased heat and pressure. Contact metamorphism-hot magma moves into the rock. Regional metamorphism-large-scale deformation. A whole mountain or cliff can deform. Agents of Metamorphism: Heat-cause chemical reactions. Minerals may recrystallize. New minerals may form From magma Heat increases as you move closer to the mantle.
Classification of Metamorphic Rocks: Pressure-increases as you get deeper also. Increased pressure causes minerals to become more compressed…more dense as well. Solutions-water may surrround crystals and make it easier for the ions to move.(Hydrothermal solutions-hot water solutions) Classification of Metamorphic Rocks: Foliated-”banding” caused by minerals realignment when crystallizing. Shale-> slate gneiss -> quartzite Non-foliated-no banding present Ex. Marble, quartzite
Anthracite Coal
Schist
Metaconglomerate