Download Rocks, Minerals, Soil, and Erosion Study Guide

Rocks, Minerals, Soil, and Erosion Study Guide
Rocks & minerals can be classified using physical attributes such as color, shape,
texture, & hardness.
A scratch test is used to determine the hardness of a rock.
Minerals are non-living solid, non-living objects formed in nature.
Rocks are naturally formed solid made of one or more minerals.
Streak tests are used to help determine what minerals are in a rock. The test shows
what color is left behind.
Types of Rocks
1. Sedimentary Rocks are formed when sand, dirt, and other materials are
squeezed together until they harden.
2. Igneous rocks are rocks that were once melted and then cooled. They are
formed form magma (lava).
3. Metamorphic rocks are rocks that are formed by heat and pressure.
Metamorphic rocks were once Sedimentary or Igneous rocks that underwent a
change due to immense heat and pressure.
Weathering is the process where rocks are broken down into smaller pieces. Wind
and rain cause weathering.
Erosion is the movement of weathered rock and soil. Moving water is the cause of
most weathering.
Very expensive minerals are called gems. They are expensive because they are very
rare and hard to find.
Soil is the loose material in which plants can grow in the upper layer of Earth. Soil is a
mixture of four different materials: tiny pieces of rock, humus, air, and water.
It takes close 500 – 1,000 years to make 1 inch of soil.
Humus is the part of soil made up of decayed living things.
Plants absorb minerals from the soil. We then eat the plants, which gives us the minerals
that is found in soil.
Water is an important part of soil. The plants take in the water they need through the soil.
Weathering is the process where wind and rain wash topsoil away, making it difficult for
plants to grow and survive.
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Rocks, Minerals, Soil, and Erosion Study Guide
Types of Soil
1. Clay is made up of very small powdery grains. Clay has small spaces between the
grains which holds lots of water, making it sticky and difficult for plants to grow.
2. Sand has large grains. This allows water to drain quickly, which keeps most
plants from getting enough water.
3. Loam is a type of topsoil and used on farms. It is rich with humus and holds
water and air well, making it ideal for plants to grow. Loam is usually dark
brown or black.
Layers of Soil
1. Topsoil has a lot of humus. Many living creatures live in the topsoil.
2. Subsoil does not have a lot of humus. It mostly contains small rocks.
3. Bedrock is the bottom layer of soil. Bedrock is mainly made up of larger
rocks.