1. What's your type? Squeeze some soil between your fingers. Is it crumbly? Sticky? A soil's texture depends on the size of its particles. And living things depend on the right texture to thrive in the soil.

2. Soil Particles Gravel: larger than 2mm; feels coarse Sand:2 - 0.05mm; feels gritty Silt:0.05 - 0.002mm; feels like flour Clay: smaller than 0.002; feels sticky when wet Every soil type is a mixture of sand, silt, clay, and organic matter.

3. Sand: Too Coarse. Soils with lots of sand have big spaces between the particles. They don't hold water or nutrients. Sand doesn't react with other chemicals. Sandy soils don't stick together very well. Plant roots can't hold onto this soil. But the big spaces do allow air into the soil. There are some plants that are able to grow in sandy topsoil by putting their roots deep, through the sand to the subsoil.

4. Silt: Too Light. This is material which is finer than sand, but still feels gritty. Silt is commonly found in floodplains and is the soil component that makes mud. Soils with a lot of silt make excellent farm land, but erode easily. This is the soil blown away in dust storms and carried down stream in floods.

5. Clay: Too Fine. Lots of clay makes the soil heavy and dense. The spaces between soil particles are very tiny. When clay soil is dry, it's almost as hard as concrete. Plant roots can't push through it. No air can get in from the surface. Most bacteria and other soil organisms that need oxygen can't breathe. But clay is important because it can change the soil chemistry. Clays give off minerals and absorb acids.

6. Loam: Just Right. The perfect soil for plants and soil organisms has about the same amount of sand and silt, plus a smaller amount of clay. This soil has enough large and small spaces for air and water to flow in. It also has enough clay to let it stick together and hold humus. These clumps make another size of space. Plant roots can easily grow through these spaces. This is what farmers and gardeners are talking about when they call a soil "aloam" or "loamy." It's the nicest thing they can say about a soil. Really.

7. Let’s take an elevator ride from the surface to the bedrock below. We’ll pass several distinct layers, or horizons, as we go. Together, these layers form the soil profile. Going down!

8. Ground level: Plants grow and animals live here. A thick cover of plants can keep the soil cool and keep it from drying out. Decomposers recycle dead plants and animals into humus

9. Topsoil: Plants grow and animals live on top of the soil. This is sometimes called the organic layer. A thick cover of plants can keep the soil cool and keep it from drying out. Decomposers recycle dead plants and animals into humus.

10. Subsoil: This is a mix of mineral particles and some humus near the top. Subsoil is very low in organic matter compared to the topsoil. This is the layer where most of the soil's nutrients are found. Deep plant roots come here looking for water. Clays and minerals released up above often stick here as water drains down.

11. Weathered parent material: This horizon can be very deep. There's no organic matter here at all. We're out of reach of all living and dead organisms down here. It's all rock particles, full of minerals. The entire soil profile used to look like this all the way to the surface. Physical weathering broke the parent material up into small pieces. Don't be fooled! This layer may contain rock particles that are different from the bedrock below. A river or a glacier might have brought it from somewhere else.

12. Bedrock: We finally found solid rock! The bedrock formed before the soil above it. It will wait here until erosion or an earthquake exposes it to the surface. Then some of it will be weathered to become the next batch of parent material. The soil-making process will start all over again.

13. Bacteria

14. Night Crawler

15. Eastern Mole

16. Pictures: Saskatchewan Interactive/Dr. Jeff Bettany | Point Pelee National Park, Canada | Steven Allison-Bunnell | USDA/Larry Rana Website: http://school.discoveryeducation.com/ http://school.discoveryeducation.com/ schooladventures/soil/name_soil.html