Igneous Rocks When hot magma cools & hardens, Igneous rocks are formed.

Magma When the temperature and pressure are just right, rocks are able to melt below Earth’s surface to form magma. When the temperature and pressure are just right, rocks are able to melt below Earth’s surface to form magma. This occurs at depths: near the surface to 150 km & temperatures: about 650˚C to 1200 ˚C. This occurs at depths: near the surface to 150 km & temperatures: about 650˚C to 1200 ˚C. Since magma is less dense than its surrounding rock it is forced upward, cools, and forms igneous rocks. Since magma is less dense than its surrounding rock it is forced upward, cools, and forms igneous rocks.

Intrusive Igneous Rocks These types of igneous rocks cool and harden below Earth’s surface. These types of igneous rocks cool and harden below Earth’s surface. So if these rocks form below Earth’s surface, how do we find them above the surface??? So if these rocks form below Earth’s surface, how do we find them above the surface??? Some examples: Gabbro, Diorite, Granite. Some examples: Gabbro, Diorite, Granite.

Extrusive Igneous Rocks Extrusive rocks - formed when lava cools on the surface of Earth. Extrusive rocks - formed when lava cools on the surface of Earth. These rocks usually cool quickly on Earth’s surface because of contact with air and/or water. These rocks usually cool quickly on Earth’s surface because of contact with air and/or water. Quick cooling rate keeps the minerals from forming large crystals, so extrusive rocks are fine-grained. Quick cooling rate keeps the minerals from forming large crystals, so extrusive rocks are fine-grained. Examples: Basalt, Scoria, Obsidian Examples: Basalt, Scoria, Obsidian

So, what about the other types of rocks? Just like energy, matter cannot be created nor destroyed (Conservation of energy/matter). Just like energy, matter cannot be created nor destroyed (Conservation of energy/matter). ROCKS = Matter! ROCKS = Matter! The formation of these igneous rocks fuels the The Rock Cycle - illustrates the conservation of matter! The formation of these igneous rocks fuels the The Rock Cycle - illustrates the conservation of matter!

The Rock Cycle (Turn to page 37)

The Rock Cycle Process that creates and changes rocks. Process that creates and changes rocks. Shows 3 types of rocks: Shows 3 types of rocks: Igneous, Metamorphic, & Sedimentary. Any rock can transform into any of the 3 rock types. Any rock can transform into any of the 3 rock types. –Rocks are the ultimate “Transformers”

Rock Cycle Paths Rocks change by many processes. Rocks change by many processes. –Weathering and Erosion –Compaction and Cementation –Melting –Cooling –Heat and Pressure

Conservation of Matter Processes of change in the Rock Cycle: NEVER create or destroy matter. Processes of change in the Rock Cycle: NEVER create or destroy matter. Materials are not destroyed, but rather transformed. Materials are not destroyed, but rather transformed. –The elements are just redistributed in different forms.