Observing Rocks 3 Types of Rocks

o What are hills, beaches and the ocean floor all made of? ROCKS!!! o Rocks are found everywhere on Earth. o All rocks have one thing in common- they are all made up of minerals.

A Rock is… o … a naturally formed solid made of grains of one or more minerals. o You can identify a rock by finding out which minerals it contains. o Rocks can be formed in many ways and in many different places.

Similar to Minerals Rocks come in many different: ◦ Sizes ◦ Shapes ◦ Colors

Texture The size and Shape of a rock affect its texture. Texture is how something feels when you touch it. Rocks can have smooth or rough textures.

Conglomerate A rock can be a conglomerate. These means that is has large grains that you can see and feel.

o Dirt, sand, and rocks form piles and layers on Earth. They are squeezed over time. Then they become sedimentary rocks. o Most sedimentary rocks have layers. o Sedimentary rock is often formed under water in lakes, rivers and streams. o The weight of the water forms the sedimentary rock.

Images of Sedimentary Rocks Sandstone Limestone

o Igneous rock is rock that was once melted and then cooled and hardened. o When lava shoots out of a volcano it comes up from underneath the earth and spills out over the earth ’ s surface. o When the lava cools off, it hardens and becomes Igneous rock.

Igneous Rock When the lava cools quickly it can look like glass. ◦ Obsidian Other times the lava cools slowly and has larger grains. ◦ Granite

o A rock may change inside Earth. Heat and pressure change the rock it becomes metamorphic rock. o It is very hot below the earth. o Rocks inside Earth can soften from the Earth ’ s high temperature. o Pressure inside Earth then squeezes the rock. This rock changes into metamorphic rock.

Images of Metamorphic Rocks Gneiss Marble