IGNEOUS ROCKS form when melted rock material cools and hardens.

Examples of igneous rocks- Rhyolite, Obsidian, Basalt, Granite and Gabbro.

SEDIMENTARY ROCKS are made up of small bits of matter joined together.  Most common sedimentary rocks are formed when sediment is compacted or cemented together.  Some are made of crystal of minerals that were once dissolved in water.

Examples of sedimentary rocks-  Shale, Siltstone, Sandstone, Limestone and Coal.

Sedimentary rocks are useful in helping piece together Earth's history. 

Limestone is used for buildings, trim, monuments, and even park benches.

Shale is often broken into pieces that are mixed with other materials to make concrete and cement.

Coal is a source of energy.

Granite                                      Gneiss

(igneous)

Shale                                          Slate

(sedimentary)

Sandstone                                 Quartzite

(sedimentary)

Limestone                                 Marble

(sedimentary)

Slate                                           Schist

(metamorphic)

People depend on soil but at times ruin and waste it.  People often get rid of garbage - Hazardous wastes, spraying chemicals, tossing plastics and foam remains, by burying them in the soil. All these materials add up to pollution.  Pollution means adding harmful substances to Earth's land.

 We can protect soil by:

1-Adding fertilizers and humus-add these materials to replace minerals

2-Using crop rotation-each year grow different crops to replace minerals

3-Strip farming-strips of tightly grown grasses are grown and trap runoff

4-Contour plowing-plow furrows across rather than up and down

5-Terracing-a hillside is shaped into a series of steps, runoff and eroded soil is trapped