Igneous Rocks- Below the earth's surface it is very hot, so hot that some rocks melt. The melted rock is called magma. When magma comes to the earth's surface it is called lava and, if the lava cools slowly, it forms visible crystals. Granite is an example of a lava-formed igneous rock containing visible crystals.

Snowflake Obsidian	Geode - natural color, cut open.	Lava

Metamorphic Rocks- When igneous and sedimentary rocks are buried deep in the earth where the temperature is very hot and the pressure is very great, they change into metamorphic rocks. Metamorphic means, "to change". Marble is an example of a metamorphic rock. Before it was changed by heat and pressure, it was limestone or slate. Slate is used to make chalkboards.

Slate	Polished Marble	Micaschist

Sedimentary Rocks - Large rocks often break into small pieces called sediment. Wind and running water move rock particles and deposit them in other locations, one layer on top of the other. Rocks formed from these layers of sediment are called sedimentary rocks. The sedimentary rocks below were found in our school district; note the materials embedded in the rocks.

Vegetation fossil in rock.		Shell imprint.
Coral fossil in rock.		Shell imprints. Rock is opened like a book.