A rock is considered a naturally occurring aggregate which is solid and is made of minerals. The Earth’s solid outer layer, called the lithosphere is made of rock. Rocks are generally classified into three different types including igneous, metamorphic, and sedimentary. The three different classes of rocks are further subdivided into many different groups. The scientific study of rocks is an essential part of geology and is called petrology.
- 3 Rock Types – Some information on the three different types of rocks including pictures and other resources.
- Rock Pictures – Shows the difference between igneous, metamorphic, and sedimentary rocks by pictures.
- Rocks & Minerals – A extensive list of resources on rocks and minerals including thematic units and lesson plans.
Igneous Rocks
Igneous rocks are formed when magma cools. Igneous rocks are divided into two different categories, plutonic and volcanic. Intrusive or plutonic rocks are the result of magma that cools and crystallizes very slowly in the Earth’s crust. Extrusive or volcanic rocks are the result of magma that reaches the surface of the Earth as lava or something called fragmental ejecta. Volcanic rocks cool much faster than plutonic rocks.
- Igneous Rocks – Some facts and information on igneous rocks including formation and other resources.
- Intrusive & Extrusive – Some pictures that show the differences between intrusive and extrusive igneous rocks.
- Igneous Rock ID – A guide featuring information on how to identify the different types of igneous rocks.
- Characteristics – A page explaining some of the unique characteristics of igneous rocks.
- Igneous Formation – Information on the formation of igneous rocks including pictures and diagrams.
Sedimentary Rocks
Sedimentary rocks are formed by a deposition of sediments or organic matter followed by compaction. Sedimentary rocks form either at or near the surface of the Earth. Sedimentary rocks are classified into different categories including mud rocks, sandstones, and carbonate rocks.
- Sedimentary Rocks – Some information and resources on sedimentary rocks, including their formation and characteristics.
- Sedimentary Types – A lesson plan aimed at teaching about the different types of sedimentary rocks.
- Sedimentary Formation – An article explaining the process that sedimentary rocks go through during their formation.
- Sedimentary Pictures – A great page of pictures that helps identify the different types of sedimentary rocks.
- Rock Facts – Some facts and information on sedimentary rocks including their unique characteristics.
Metamorphic Rocks
A metamorphic rock is formed when any type of rock is subjected to different pressure or temperature conditions than when it was formed. The changes in temperature and pressure are high and change the original minerals into other types or other forms of the same minerals.
- Foliated & Nonfoliated – Some pictures showing the difference between foliated and nonfoliated metamorphic rocks.
- Metamorphic Lesson – A lesson plan featuring information on the agents of metamorphism and its relationship to plate tectonics.
- Metamorphic Rocks – A page of easy to understand information on metamorphic rocks.
- Metamorphic Formation – Information on how metamorphic rocks are formed including pictures and diagrams.
- Rock Lesson – A lesson explaining metamorphic rocks including their formation, and unique characteristics.
