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TYPES OF ROCK and THE ROCK CYCLE. IGNEOUS ROCK- formed when molten rock cools and solidifies. As the rock cools, minerals crystallize and grow. Extrusive igneous rock - cools quickly on the Earth ’ s surface (small crystals) Ex: Basalt, Obsidian
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IGNEOUS ROCK-formed when molten rock cools and solidifies. As the rock cools, minerals crystallize and grow.
Extrusive igneous rock- cools quickly on the Earth’s surface (small crystals) Ex: Basalt, Obsidian Air bubbles are sometimes trapped (pumice, scoria)
Intrusive igneous rocks- cools slowly under the Earth’s surface (large crystals) Ex: granite, gabbro
2. SEDIMENTARY ROCK- formed from compressed or cemented layers of sediment *starts with rock being weathered (broken down) by wind/rain/ice *then the sediments move to lakes and seas and sink
Layers form as larger sediments sink first and smaller sediments stay “suspended”
Named based on the size of the fragments they contain: Conglomerate = pebbles Sandstone = sand Mudstone = mud (if it’s flaky it’s called shale) Limestone = made mostly of fossils and shells of sea creatures
SEDIMENTARY ROCKS: Sediments compacted and cemented
3. METAMORPHIC ROCK- rock that changes form under heat/pressure deep within the Earth * Heat and/or pressure is great over long amounts of time, but the rock does not melt. Limestone --------> Marble
METAMORPHIC ROCKS: Changing under heat/pressure