1. Rocks
Mt. Rushmore is made from granite – an igneous rock

2. Rocks can be put into one of 3 categories
based on how they were created

3. These 3 types are:
Sedimentary Rock
Igneous Rock
Metamorphic Rock

4. SEDIMENTARY ROCKS
3 things need to happen
FIRST an existing rock must be weathered and ERODED by for wind and/or water over a long time.
SECOND – sediments must gather
THIRD – pressure gets added to the sediments to squeeze layers of sediment together …
Layers are deposited on top of lower layers. Lower layers become ROCK.

5. Shale
Shale is a type of sedimentary rock formed from mud and clay that is compacted together by pressure.
It is used to make bricks and other material that is fired in a kiln.

6. Limestone
Limestone is a sedimentary rock made from the mineral calcite which came from the beds of evaporated seas and lakes and from sea animal shells.
This rock is used in concrete and is an excellent building stone for humid regions.

7. Sandstone
Sandstone is a sedimentary rock made from small grains of the minerals quartz and feldspar.
It exists in layers as seen in this picture.
It is often used as building stones.

8. Conglomerate
Conglomerate is a sedimentary rock with large sediments like gravel, sand and pebbles combined with clay.
It is often formed during or immediately after a large storm.
The sediment is so diverse that pressure alone cannot hold the rock together; it is also cemented together with dissolved minerals.

9. Gypsum
Gypsum rocks are sedimentary. Sulfate minerals combine as sea water evaporates in large basins.
It is very soft and is used to make Plaster of Paris, casts, molds, and Drywall.

10. IGNEOUS ROCK Igneous rocks form either underground or above.
Underground, magma becomes trapped in pockets. As these pockets of magma cool, Intrusive igneous rocks form.
When volcanoes erupt, magma rises above the earth's surface. Magma above the earth is called lava.
Extrusive Igneous rocks are formed as the lava cools above ground.

11. Granite
Granite (Intrusive igneous) formed by slowly cooling pockets of magma trapped beneath the earth's surface.
Granite is used for long lasting monuments and for trim and decoration on buildings.

12. Pumice
Pumice (Extrusive igneous) forms when lava cools quickly above ground. You can see where little pockets of air had been.
This rock is light. Many pumice rocks will actually float in water.
Pumice is actually a kind of glass and not a mixture of minerals.

13. Obsidian Extrusive igneous rock high in Silica.
Obsidian is actually glass and not a mixture of minerals.
Sand or sandstone was melted to form this rock.
The edges of this rock are very sharp.
Obsidian has “Concoidal” cleavage.

14. METAMORPHIC ROCK
have "morphed" (changed) into another kind of rock. - were once igneous or sedimentary rocks.
tons and tons of pressure, (which fosters heat build up), or a nearby heat source causes change, WITHOUT ENTIRELY MELTING.
If you examine metamorphic rock samples closely, you'll discover flattened original grains in the rock and “bands”.

15. Schist
Schist can be formed from basalt, an igneous rock; shale, a sedimentary rock; or slate, a metamorphic rock.
It has flat / planar minerals such as micas, talc, and graphite.
SHISTS provide things like TALCUM POWDER and graphite for pencils and printers.

16. Gneiss
Gneiss (“nice”) rocks are metamorphic. They were once granite. Heat + pressure changed it.
Original mineral grains were flattened through tremendous heat and pressure and are arranged in alternating banded patterns.
BANDS look like sedimentary layers. Metallic minerals accumulate near GNEISS. For a mining Geologist, it is nice to find GNEISS.

17. THE ROCK CYCLE