The Rock Cycle Objective: Student will identify and classify the characteristics of the rock cycle by the end of the lesson.

The Rock Cycle Essential Question: What are the stages of the Rock cycle?

The Earth’s Rock Cycle The earth’s rocks can be classified into 3 main categories: Igneous rock, Sedimentary rock, Metamorphic rock Though they are very different, these rocks are related. They are linked in a cycle.

Igneous Rock The rock cycle begins with the oldest rock form, Igneous Rock. Igneous rock is formed when melted rock or magma erupts from the earth as lava and cools.

Types of Igneous Rock There are many types of igneous rocks. There characteristics are determined by how fast the rock cooled, the mineral content, and the metal content. Granite is an example of igneous rock that cooled slowly underground. Obsidian (ob•sid•i•an) and pumice (pum•ice) are examples of igneous rocks that cooled quickly.

Sedimentary Rocks Sedimentary rocks are the second great rock class. Whereas igneous rocks are born hot, sedimentary rocks are born cool at the Earth's surface, mostly under water.

Types of Sedimentary Rock There are many types of sedimentary rocks. Some examples are: Sandstone Limestone Shale Conglomerate Gypsum

Forming Sedimentary Rock For thousands, even millions of years, little pieces of our earth have been eroded (broken down and worn away) by wind and water. These little bits of Earth are washed downstream where they settle to the bottom of the rivers, lakes, and oceans. Layer after layer of eroded earth is deposited on top of each other. These layers are pressed down more and more through time, until the bottom layers slowly turn into rock.

Weathering Sedimentary rock is formed when igneous rock is exposed to weathering. Weathering is simply the breaking down of rocks into smaller pieces. This process is called erosion. There are 3 kinds of weathering: Mechanical Chemical Biological

Types of Weathering Mechanical weathering occurs when heat, cold, ice, windblown sand, and water falls slowly crack and wear down rocks. Chemical weathering is when rock is dissolved by the acids in rain water. Biological weathering happens when plant roots crack and dissolve rock.

Lithification Weathering occurs very slowly. The result is sand, dust, clay, and minerals that dissolve in water. These elements are carried by wind or water and eventually settle in layers. Over time, these layers form new types of rock. This process is called Lithification (lith•i•fi•ca•tion).

Metamorphic Rock Metamorphic rock is rock that goes through a metamorphous or changes brought on by heat or pressure. The heat is not enough to melt the rock but it is enough to alter its original characteristics. An example of metamorphic rock is marble. Heat and pressure change limestone, a soft rock into marble, a hard rock.

Vocabulary Erosion (v) The gradual (slowly, a little at a time) wearing away of soil and rock by forces such as water and wind (weather). Igneous (n) A kind of rock formed when melted rock (lava) cools. Metamorphic (n) A type of rock formed when another rock is changed by heat or pressure. Sedimentary (adj) Rocks formed from layers of sediment pressed together. Sediments (n) Particles that settle in a liquid. Weathering (v) The breaking down (erosion) of rocks into smaller pieces. Lithification (v) The process that turns sediments into stone Magma (n) Liquid or molten rock deep in the earth Lava (n) The magma released or ejected from a volcano