By W.Batke Teacher Notes Activity Soil Formation Part 1

Soil Formation What are the two main ingredients that make up soil?

Soil Ingredients Weathered Rock Humus InorganicOrganic

What do the terms organic and inorganic mean?

Let us look at the Inorganic component: Over time wind, water and ice break the rock down into smaller and smaller particles

Finally, all that is left is sand, silt and clay.

In many cases the original weathered rock called the parent material lies below the developing soil.

Of course this takes long time.... In most cases distinct soil layers develop. These are referred to as soil horizons.

Can you see the different soil horizons in this diagram? Horizon A Horizon B Horizon C Weathered Bedrock

Can you identify the soil horizons? Horizon A Horizon B Horizon C Weathered Bedrock

Many times soil profiles are changed by Floods, Remember the Flood of 1993 ?

Soil profiles record these events Here is sediment laid down by a flood. Can you think of land in the Hazelwood School District that has been flooded?

Depending on climate some rock never develop into soil horizons.

The amount of sand, silt and clay can influence soil texture and use.

Soils with high sand content

Soils with high silt content

Soils with high clay content

But our picture is not complete. Without the organic component, the soil is unproductive.

Next time we will look at the organic component.

Teacher notes: Back to start *Slides that do not advance automatically must be advanced manually by left clicking on the mouse button. *Back arrows on each slide move to previous slide. *Topics are intended to be discussed in class and science journal notes or records are encouraged. *Programs may be viewed in any sequence although they tend to build upon one another. Soil Importance, Soil Formation Pt.1, Soil Formation Pt.2 Soil Conservation, Soil Problems More

Here are some additional resources on the web If you have questions, comments, please send to Back to start