Rocks 6.E.2.1 Summarize the structure of the Earth, including the layers, the mantle and core based on the relative position, composition and density.

GRANITE (igneous rock) Igneous Rocks Igneous rocks form when magma cools and hardens. Igneous from the Latin meaning “Fire formed,” is a rock type that forms from the solidification of a molten mineral solution. BASALT (igneous rock) GRANITE (igneous rock) 2

Igneous Rocks Igneous rocks are classified according to their origin, texture, and mineral composition. Origin Igneous rock may form on or beneath Earth’s surface. Extrusive rocks form on the Earth’s surface (above ground) when lava cools quickly to create small crystals. (Extrusive = Exit/outside) Intrusive rocks form inside the Earth (underground) when magma cools slowly to create large crystals. (Intrusive = Inside) The most abundant intrusive rock in continental crust is granite.

Igneous Rocks Intrusive rocks have larger crystals than extrusive rocks. Extrusive rocks have a fine-grained or glassy texture. Intrusive: Large crystals Extrusive: Small crystals

Igneous Rocks Texture refers to the crystal size. Textures are divided into two main types: Fine-grained = crystals are too small to see (basalt) Coarse-grained = crystals are easily visible (granite) Coarse Grained: Large crystals Fine Grained: Small crystals

Igneous Rocks Mineral Composition Lava that is low in silica usually forms dark-colored rocks such as basalt. Magma that is high in silica usually forms light-colored rocks, such as granite. Uses of Igneous Rocks People throughout history have used igneous rock for tools and building materials.

Sedimentary Rocks Sediment is small, solid pieces of material that come from rocks or living things. Rocks that are composed of the weathered remains of preexisting rock, or plant and animal remains. Most sedimentary rocks are formed through a series of processes: erosion, deposition, compaction, and cementation. Horizontal layers called “Beds” separated by “Bedding planes,” are a common feature in sedimentary rocks.

Sedimentary Rocks Erosion In erosion, running water, wind, or ice loosen and carry away fragments of rock.

Sedimentary Rocks Deposition Deposition is the process by which sediment settles out of the water or wind carrying it. Compaction The process that presses sediments together is compaction. Cementation Cementation is the process in which dissolved minerals crystallize and glue particles of sediment together.

Sedimentary Rocks Conglomerate – cemented sand, silt, and pebble sediments. Sandstone – cemented quartz sand grains. Feels gritty. Unfilled spaces between grains make most sandstones porous and permeable to water.

Sedimentary Rocks Types Clastic Rocks Most sedimentary rocks are made up of broken pieces of other rocks. A clastic rock is a sedimentary rock that forms when rock fragments are squeezed together. Organic Rocks Not all sedimentary rocks are made from particles of other rocks. Organic rock forms where the remains of plants and animals are deposited in thick layers. “Organic” once were part of living things or were made by living things. Ex.) coal & limestone

Sedimentary Rocks Chemical Rocks When minerals that dissolved in a solution crystallize, chemical rock forms. Ex.) Limestone can form when calcite that is dissolved in lakes, seas, or underground water comes out of solution and forms crystals.

Sedimentary Rocks Uses of Sedimentary Rocks People have used sedimentary rocks through out history for many different purposes, including building materials and tools. The White House is built of sandstone.

Metamorphic Rocks Metamorphic rocks form from HEAT and PRESSURE changing the original or parent rock into a completely new rock. The parent rock can be either sedimentary, igneous, or even another metamorphic rock. Every metamorphic rock is a rock that has changed its form.

Metamorphic Rocks FORMATION OF METAMORPHIC ROCK The word "metamorphic" comes from Greek and means "To Change Form".

Metamorphic Rocks The deeper a rock is buried in the crust, the greater the pressure on that rock. Under high temperature and pressure many times greater than Earth’s surface, the minerals in a rock can be changed into other minerals. The rock has become a metamorphic rock.

that cause an increase in PRESSURE Metamorphic Rocks Solid rock can be changed into a new rock by stresses that cause an increase in PRESSURE metamorphic rock that cause an increase in HEAT HEAT from the core

Metamorphic Rocks

Metamorphic Rocks Types of Metamorphic Rocks Geologists classify metamorphic rocks according to the arrangement of the grains that make up the rocks. Foliated Rocks Metamorphic rocks that have their grains arranged in parallel layers or bands are said to be foliated. Nonfoliated Rocks Mineral grains are arranged randomly.

Metamorphic Rocks Forming Metamorphic Rocks – Great heat and pressure can change one type of rock into another.

Metamorphic Rocks Uses of Metamorphic Rock Certain metamorphic rocks are important materials for building and sculpture. Marble and slate are two of the most useful metamorphic rocks. Garden Sculpture

Questions What type of rocks form when magma cools and hardens? A. It depends on the location. B. Sedimentary C. Metamorphic D. Igneous

Metamorphic rocks form from _____________ and ______________. A Metamorphic rocks form from _____________ and ______________. A. heat, ice B. heat, pressure C. ice, pressure D. water, minerals

What type of rocks are formed from the weathered products of preexisting rocks that have been transported by water, wind, or glaciers? A. Igneous B. Metamorphic C. Sedimentary D. All of the above

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