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I Will Be Able To… • Arrange and define 4 stages of sedimentary rock formation. • Describe the difference between intrusive and extrusive igneous rock. • Recognize the difference between foliated and unfoliated • List common uses for 3 different types of rocks • Apply the rock cycle • Distinguish between the 3 classifications of rocks • Illustrate how a rock becomes a metamorphic rock • Evaluate rocks to determine their classification and names
Definition • Rocks are the hard part of the earth • Rocks are composed of one or more minerals • Rocks can be made up of organic matter
How to Classify Rocks Color Mineral Composition Texture Grain size Grain shape Grain pattern
Color • This is a quick easy to observe property that can point you in the right direction. • Helps identify mineral composition Granite
Texture • Grain size • Grain pattern • Grain shape
Grain Size Fine Grained Medium Grained Course Grained
Grain Shape Rounded grain Angular grain
Grain Pattern Banded Non Banded
Three Classifications of Rocks • Igneous • Sedimentary • Metamorphic
Igneous rocks Fire rocks
Igneous • Igneous Rocks are formed form lava or magma.
Extrusive • Rocks formed form lava. These are also called volcanic rocks. • Pumice • Basalt • Obsidian
Intrusive • Formed from magma • Granite • Gabbaro • Diorite
Cooling Rates • Fast cooling have shinny reflections. • Slow cooling have visible crystals
Granite • Light-colored, coarse- grained, no pattern • Mostly quartz, feldspar, mica, and hornblende • Often used for buildings and monuments
Basalt • Dark-colored, fine- grained, extrusive • Formed where lava erupted onto surface • Most widespread igneous rocks • Found locally in the Palisades along west shore of Hudson River, Connecticut River valley
Gabbro • Dark-colored, coarse- grained intrusive • Similar composition to basalt—plagioclase feldspar with some pyroxene and olivine
Obsidian • Natural volcanic glass • Forms when lava cools very quickly • Usually dark, but small pieces may be clear • Fractures along curved (conchoidal) surface • Used as spear and arrow points, knives
Uses Buildings Countertops Soap Aggregate
Sedimentary Rocks Packed Rocks
Sedimentary • Formed from fragments of rocks and minerals that break up or dissolve into water.
Formation Process • Erosion • Deposition • Compaction • Cementation
Erosion • Wearing away of rocks by wind, water, or ice.
Deposition • Sediment settling out of the wind or water that is carrying it.
Compaction • Process of sediment settling together
Cementation • Process of dissolved minerals crystallizing and gluing rock sediments together.
Types • Clastic • Organic • Chemical
Clastic • Sedimentary Rocks composed of sediment and rock fragments that have been deposited, compacted and cemented.
Pink sandstone • Pink or reddish in color • Composed of quartz and feldspar minerals • Texture • Medium Grain Size • Angular or Rounded Grain • Well sorted, no banding • Slightly porous
Conglomerate • Color • Tan to dark brown with nearly any color spots • Fragments of all types of rocks usually cemented by quartz, iron oxides, or calcite. • Texture • Very course • Rounded Grain • Non banded
Breccia • Color • Light brown or tan with grey white or black spots • Composed of all types of rocks and cemented by salts • Texture • Very course • Angular • Non banded
Organic • Made from the organic material that has been deposited, compacted and cemented
Coal • Color • Black or dark grey • Texture • Medium-Fine grained • Angular or rounded • Non banded
Organic/Fossil Sandstone • Color • Light colored, white to yellow or tan • Texture • Medium or fine grained • Angular fragments • Non banded • May have distinct fossils
Diatomite • Color • Light brown or tan • Composed of silica from hard celled algae • Texture • Fine grained • Rounded or Angular • Non banded • Powdery
Chemical • Rocks that are formed form minerals that were once dissolved in water usually left behind after evaporation.
Rock Gypsum Alabaster Rock Salt
Uses Building Stones Cement Fiberglass Fuel
Metamorphic Rock Changed Rock
Metamorphic • Formed by heat and pressure of other rocks deep in the earth
Regional • Plates get pushed under and thus pressurized and heated • Plates get pushed up into mountains
Contact • Lava veins shooting up near rock give off intense heat
Foliated • These rocks have a banded texture. • Can layers of the same rock or of crystals