Soil Is The Geologist S Word For Dirt

Soil is the loose covering of broken rock particles and decaying organic matter, called humus, overlying the bedrock of Earth’s surface.

Soil contains approximately

45 % mineral 25 % water 25 % air 5 % organic

matter

1. Parent Rock is the original rock which is broken down. The parent rock contributes the type of minerals found in the soil.

Climate may be the strongest factor effecting climate.

Temperature and precipitation will determine whether chemical or mechanical weathering will take place. Along with the type of plant and animal life present.

The primary source of organic matter in soil is plants, but animals also contribute. When organic matter is decomposed important nutrients are supplied to the soil.

The actions of microorganisms like fungi and bacteria and animals such as earthworms and moles, mix and move the soil and add to the enrichment process of forming the soil.

The slope of the land can influence the moisture and erosion of soil.

Steep slopes are often poorly developed because water is being run off and with no plant growth the erosion process quickens

In contrast, poorly drained low lying areas can be thick and dark It can be too wet and also have a lack of oxygen develop into a fertile soil.

It takes 100 years to form 1 inch of soil. The longer a soil has been forming, the thicker it becomes and the less it resembles the parent material.

The vertical differences, which become more pronounced as time passes, divide into zones or layers known as horizons.

This is called the soil profile.

There are 3 major divisions in the soil profile. The top is the A layer. High organic matter and humus are found here.

Soil layer B is enriched with clay minerals. Many subsoils have a zone of accumulation consisting of soluble minerals that have been leached or washed out from the topsoil. They can be red or brown in color as a result of the presence of iron oxides.

Layer C is directly above the parent rock or bedrock. This layer contains weathered parent material and no organic material.