Chapter 4 - Rocks What can be learned by studying rocks… We can learn mo better about earth. So what is a rock??? It’s a mixture of 1 or more minerals. Easy.

The Rock Cycle Shows how any rock may be transformed from one type into another. It’s a continuous process that causes rocks to change.

Vocab terms Magma – underground molten rock Lava – above ground molten rock Crystallization – formation of minerals from cooling magma/lava Weathering – any process that breaks down rocks into smaller pieces (sediment)

Vocab terms Erosion – transportation of sediment Deposition – accumulation of sediment Metamorphism – changing one type of rock into another by heat/pressure/chemicals Lithification – compaction and cementation of sediment

Igneous Rocks…from fire 2 main types Intrusive (large crystals) From magma Underground Cools and forms slowly Extrusive (small crystals) From lava Above ground Cools and forms quickly

Igneous Rocks Classification 2 ways to classify igneous rocks 1 = Texture 2 = composition 1. Texture (3 types) Coarse grained – slow cooling, large crystals Fine grained – fast cooling, small crystals Glassy – super fast cooling, glassy Porphyritic – slow and fast cooling, has both large and small crystals

Andesitic (intermediate) Ultramafic 2. Composition Granitic (felsic) High in silica (SiO4), light colored, lower density Basaltic (mafic) Low in silica, dark colored, high in iron and magnesium higher density Andesitic (intermediate) Ultramafic

Sedimentary Rocks Your teacher rocks!

Sedimentary Rocks From (Latin) sedimentum = settling Made from sediments of any type 4 agents of erosion (transportation) Water Wind Glaciers Gravity

3 Types Sedimentary Rock Clastic = formed from sediment Chemical = formed from precipitation or evaporation…dried up soda on a table Biochemical (organic) = formed from remains of once living organisms

1) Clastic Sedimentary Rocks Conglomerate – rounded pebble sized Breccia – angular pebble sized Sandstone – sand sized Siltstone – silt sized Shale – clay sized

2) Chemical Sedimentary Rocks Crystalline limestone – precipitates from ocean water Gypsum – precipitates from oceans, too Travertine – precipitates in caves Chert/flint – quartz Rock salt – evaporated salt water

3) Biochemical Sedimentary Rx Fossil limestone – fossil remains Coquina – shells and shell fragments Chalk – microscopic shells and clay Bituminous coal (B coal) – plant remains

Metamorphic Rocks Means to change form 2 types of metamorphism 1. Contact - small areas from toughing hot magma 2. Regional - large areas from the pressures of mountain building

Agents of Metamorphism Heat (temperature) Pressure (stress) Reactions in hot solutions (chemicals)

Metamorphic Rock Classification 2 textures Foliated - layered Nonfoliated – not layered

1. Foliated Metamorphic Rx A) Slate – very thin layers from shale Phyllite – thin layers, sheen, wavy, from slate Schist – medium layers,shiny, micas, from phyllite Gneiss – distinct black & white layers, from schist or granite

2. Nonfoliated Metamorphic RX Marble – shiny, fizzes in acid, H = 3, from limestone Quartzite – shiny, won’t fizz, H = 6 – 7, from sandstone Anthracite coal – shiny, black, from bituminous coal The carbon cycle…see page 85

TREE Igneous Rx A) Intrusive