Rocks, Minerals, and Soil
Properties
We use many different kinds of words to describe and sort rocks including:
ColorLuster (dull or shiny)
Texture Hardness
Transparency
Igneous Rocks
Igneous means made from fire or heat
There are two major types of igneous rock; extrusive and intrusive
Extrusive is created when magma comes to the earth’s surface and becomes lava. When lava cools, it becomes rock, such as obsidian
Intrusive like granite is formed inside the earth’s crust when magma hardens
Obsidian Granite
Basalt*Google images
Sedimentary
Large rocks break down into smaller rocks and sand (sediment)
Over time, this sediment settles to the bottom of bodies of water and creates sedimentary rock due to time and pressure
Fossils are found in sedimentary rocks
It can often be identified by its layered or conglomerate design or sandy texture
http://www.fi.edu/fellows/fellow1/oct98/create/sediment.htm
*Google images
Metamorphic
Metamorphic means to change form
They are created when sedimentary and igneous rocks are heated, squeezed and folded during movement of the earth’s crust
Marble is a metamorphic rock Banding and layering can
occur; they are the least common of the three kinds of rocks
Gneiss Marble*Google images
Soil
Soil is made of:
-air and water
-living organisms
-organic matter ( leaves, grass, twigs, roots)
-rocks and minerals
-decomposed plants and animals
Soil is different from place to place because of weather and climate, parent material, and organisms.
How is soil created?
Soil is created over time by:
-rocks and minerals breaking down; weathering and erosion: wind, water, chemical, ice, plant
-decomposition
Clay
There are three types of soil, and they are classified by their texture and particle size.
In clay, particles are small and they clump together.
When wet, clay soil feels like modeling clay.
Clay doesn’t drain water very well because it is packed together tightly.
Silt
Silt has smaller particles than sand, but larger particles than clay.
Silt’s texture is similar to that of flour, powdery.
It is the darkest and loosest of the three soils.
Sand
Sand has the largest particles (like sugar).
Its texture is gritty.
It has the best ability to drain water out of all three types of soil.
- www.rain.org
Soil Profile
O: Organic Matter A: Topsoil (loam) E: Subsoil- mostly silt
and sand B: Subsoil- mostly clay C: Parent Material R: Bedrock
What if there was no soil?
Without soil we wouldn’t have blue jeans! Jeans are made of cotton denim stitched together with cotton thread. Their blue color comes from indigo dye.
Cotton and indigo come from plants that need soil to grow. If we did not have soil healthy soil the plants
necessary to make jeans would not exist!