5 Three Main Groups of Sedimentary Rocks: 1. Clastic 2. Chemical II. Sedimentary Rock – rock that forms over time as sediment is squeezed and cemented togetherSediment – small, solid pieces of material that comes from rocks or living organismsSediment is deposited in layers by running water or windSediment is cemented together by pressure from overlying layersThree Main Groups of Sedimentary Rocks:1. Clastic2. Chemical3. Organic
6 Clastic Rock – sedimentary rocks that form from the broken fragments of other rocks Clastic Rocks are classified based on the size of their fragmentsExample: Conglomerate – rock fragments that consist of gravel and pebbles
7 Some clastic rocks are made of smaller particles (sandstone)
8 2. Chemical Rocks – rocks that form when minerals precipitate out of solution Example: when ocean water evaporates (halite)
9 Organic Rocks– rocks that form as a result of organic processes Shells of marine animals like corals, clams, mussels sink to the ocean floor when they die.Example: Limestone and calcite (chalk)
10 III. Metamorphic Rocks – rock that have been changed by temperature, pressure, or chemical reactions.Most metamorphic rocks form under high temperatures and pressures deep underground. (slate and schist– shown below)
11 Metamorphic RocksFoliation: a layering of minerals in a rock due to intense pressure squeezing the crystals together.
12 Metamorphic Rock pictures Metamorphic Rocks like gneiss show banding of light and dark minerals.
13 Metamorphic Rocks and their Parent Rocks Examples:Slate: parent is shaleGneiss: parent is granite/schistQuartzite: parent is sandstoneMarble: parent is limestone
14 IV. Rock CycleRock Cycle – series of processes in which rocks continuously change from one type to another.