Rocks – naturally formed, non-living masses of solid Earth material that are made up of minerals.
There are three types of rocks:
1) Sedimentary – sediments
2) Metamorphic – change in form
3) Igneous – from fire (magma/lava)

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Form from the compaction and cementation of sediments
Compaction means squeezing together of sediment layers
Cementation means binding or gluing together of sediment particles
As sediments become deposited, compaction and cementation occur because of the pressure pushing down – represented by the arrows.
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Lithification is the formation of loose sediments into solid rock
Sedimentary rocks form in horizontal layers and have horizontal sorting
Sedimentary rocks usually contain fossils.

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Clastic sediments – rock/mineral fragments from weathered rocks (clay, silt, sand, pebbles, cobbles, boulders)
Organic sediments – particles produced by life activities of plants or animals. ex: shells (clams), skeletons (limestone coquina), calcium carbonates. Peat – plants that lived in swamps.
Plant life  peat  soft coal  hard coal  diamonds
3) Chemical evaporites – when ions (atoms with charges) join together, forming crystals that settle (precipitate) out of solution.
ex: halite and gypsum

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 Metamorphic means to change form
 Metamorphic rocks are formed when great heat and pressure are applied to existing rocks (sedimentary, metamorphic or igneous)
 The existing rock before metamorphism is called the parent rock.

 Contact – when molten material comes into contact with surrounding rocks.
 Regional –Large areas associated with mountain building (orogeny). When deeply buried rocks are squeezed, movement of these layers will occur.
EX: The Adirondack mountains are formed by regional metamorphism.

Characteristics of Metamorphic Rocks
1) Crystalline texture – pressure can create large and small crystals to form. Pressure may cause large crystals to break into smaller ones. Most metamorphic rocks have crystalline texture.
2) Increased density – grains are compressed closer to each other. Smaller volume, higher density.
3) Foliation and Banding a) Foliation – crystals arranged in layers or bands in along which rocks are broken easily.
b) Banding – minerals of different densities recrystallize with great pressure and separate into layers.
4) Distortion of layers – softened by heat and squeezed by pressure.

 Slate – parent rock is shale
 Phyllite
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Schist
Gneiss – parent rock is granite
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Hornfels
Quartzite – parent rock is sandstone
Marble – parent rock is limestone

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Formed by recrystallization of molten rock material (magma)
Igneous rocks contain crystal grains!
1) The crystal size is directly related to the cooling time.
a) Slow Cooling – large crystals, feels rough.
b) Fast Cooling – small crystals, feels smooth.
c) Very Fast Cooling – no crystals, looks and feels like glass.
There are TWO MAJOR groups:
1) Intrusive (from magma) – cooled beneath/inside the surface
2) Extrusive (from lava) – cooled at or near the surface.
** All igneous rocks are silicates (contain Si and O) but they vary in composition, color and density. They can be felsic (contain Al) or mafic (containFe).**