Sedimentary and Metamorphic Rocks Chapter 6

Formation of Sedimentary Rocks Sediments- pieces of solid material that have been deposited on the earth’s surface by water, wind, ice, gravity, or chemical precipitation. Weathering- a set of physical and chemical properties that break rock into smaller pieces. 5.1

Formation of sedimentary Rocks Clastic sediments- rock and mineral fragments formed by weathering 5.1

Formation of Sedimentary Rock Erosion- the removal and movement of surface materials from one location to another. Wind Water (moving) Gravity Glaciers 5.1

Formation of sedimentary rocks Deposition- sediments are dropped by the erosional force in a new location causing them to “pile” up on each other. Largest sedments typically settle out first (bottom) Small sediments typically settle out last (top) Not all sediments are sorted-- glaciers 5.1

Formation of sedimentary rocks Burial- sediments are typically deposited on low areas of the earth called sedimentary basins. The sediments layer or “pile” on top of each other causing lithification 5.1

Formation of Sedimentary Rock Litification- physical and chemical process of changing sediment into sedimentary rock Begins with pressure (weight) of the overlying sediments forcing grains of sediments below close together. Sediments buried 3-4km below the earth’s surface will experience relatively high temperatures causing cementation. 5.1

Formation of sedimentary rock Cementation- occurs when mineral growth cements sediment grains together into solid rock. New mineral forms from ground water precipitation. Existing mineral grows larger 5.1

Features of sedimentary rock Bedding- horizontal layering Graded bedding- particle size becomes progressively heavier and larger toward the bottom. 5.1

Features of sedimentary rock Cross bedding- formed when inclined layers of sediment move forward across a horizontal surface 5.1

Features of sedimentary rock Fossils- preserved remains, impressions, or any other evidence of once-living organisms 5.1

Types of sedimentary rocks Clastic sedimentary rocks- form from deposited loose sediment Course grained- gravel-sized rock and mineral fragments (conglomerate)

Types of sedimentary Rocks Clastic Medium grianed- sand-sized sediments (sandstone)

Types of sedimentary rocks Red Rock Canyon, Nevada Clastic sandstone

Types of sedimentary rocks Clastic sandstone Balanced sandstone formation at Red Rock Canyon

Types of sedimentary rocks Clastic sandstone

Types of sedimentary Rock Clastic Fine grained- silt and clay size particles (shale)

Types of sedimentary rocks Chemical- minerals dissolved in water are left behind when the water evaporates Evaporites- most common calcite, halite, gypsum

Types of sedimentary rock Chemical Organic- formed from the remains of organisms (limestone)

Metamorphic rock Metamorphism- change in the combination of minerals in a rock because of added heat and pressure. Regional metamorphism- metamorphism in a large region of the earth’s crust.

Metamorphic Rock Contact metamorphism- occurs when molten rocks come in contact with other rocks. Hydrothermal metamorphism- very hot water reacts with rock. Metamorphic Sedimentary

Metamorphic rock Metamorphic textures- Foliated- wavy layers or bands Nonfoliated- rocks that lack mineral grains in bands. Porphyroblasts- some minerals will grow large and be surrounded by other smaller minerals. Nonfoliated porphyroblast foliated Chlorite and Biotite Gneiss Marble

Metamorphic rock Solid state alterations- a mineral changes to a new mineral without melting.  Granite Gneiss

Rock Cycle