Learning About Rocks

Learning About Rocks

In this article we will learn about the three types of rocks. We will also cover simple rock collecting techniques.

The entire earth is covered with rocks. The upper crust is the top layer of the earth. The lower crust is the second, followed by the rock mantle. Below the rock mantle is magma.

Sometimes magma pushes its way through the layers of the earth and surfaces in a volcano. When the magma surfaces, it is then called lava.

There are three types of rocks, igneous, sedimentary and metamorphic.

Igneous rock is rock that has formed with the aid of heat. Granite and Quartz are forms of igneous rock. Basalt is the most common igneous rock.

Sedimentary rock is rock that has formed by layers of material such as, clay or sand, which have pressed down upon each other until the pressure forms a rock. Sandstone and shale are both sedimentary rocks. Many times fossils can be found in sedimentary rocks.

There is a mountain near our house which is covered with shale. As we walk along this mountain it is nearly impossible to not find a fossil. They cover the ground. On this same mountain we have found many quartz crystals.

Often times, shell imprints are visible in the sedimentary rock of limestone. Calvert Cliffs is a bay area in Maryland where many fossils can be found in the sedimentary rock. My family has found many sharks teeth, coral, and shell fossils there.

Metamorphic rock is rock that has changed from one type to another. Normally this occurs by means of heat and pressure. Slate is a metamorphic rock. Shale turns into slate. Limestone turns into marble.

All rocks are graded according to their hardness. The scale ranges from 1 to 10. Talc is a very soft rock and rates as a 1 on this scale. Diamonds are very hard and rate as a 10. Talc is so soft you can break it with your fingers, but diamonds are so hard they can scratch glass!

Rocks can be collected in egg cartons and labeled with simple paper labels. Larger rocks can have a label attached to the bottom by means of masking tape. Discount stores also sell inexpensive plastic containers with built in dividers, which can be used to store collected rocks.

Rocks have been used for thousands of years as building materials, and sources of value. The Romans paved roads thousands of years ago, with huge rocks. The Egyptians made the pyramids with even larger rocks.

Rocks have been a sign of wealth for thousands of years. Rare rocks, ones that are hard to find,

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