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Soil Layers

Homes and buildings are built on top of the foundation, which sometimes rests in different layers of soil.

When the earth as we know it was being formed, wind, glacial deposits, and erosion created different layers of soil. Builders can contribute to creating additional layers of fill soil when they move hills to pave way for construction sites.  

Let’s look at five types of soil layers so you can understand how they came into existence. 

Soil layers

What Are Soil Layers? 

The term “soil layers” refers to a soil horizon that runs parallel to the soil surface. Each layer of soil has unique biological and chemical characteristics from the preceding or subsequent layer. Soil layers gain strength and stability with time. Water, wind, glaciers, and human activity all have a hand in the formation of soil layers.  

Some layers of soil are good for construction, while others are hotbeds for structural problems. Your Denver, CO, home is likely built across different layers of soil. Each layer has a different depth and characteristics to suit various types of structures. 

Different Types of Soil Layers 

Fill Soil 

With a lot of construction work going on, soil for foundations is becoming scarce. Sometimes, builders are forced to bring in soil from other locations to cover up hollows and depressions in the ground. The soil taken from a different area is called fill soil. 

Fill soil supplies a sturdy base for construction work. It consists of a mixture of rocks, clay, and sand which provide more stable construction material. It’s mostly used for large construction projects and landscaping. It’s used to level up the ground around the foundation area and fix water drainage issues. Fill soil also secures the ground and retains walls.  


Also known as load-bearing strata, bedrock is a solid layer of the earth. It’s made up of sandstone, limestone, and other types of rocks. It’s stable and weather resistant. The bedrock can be exposed or buried under the soil, sometimes going hundreds of feet deep. 

Bedrock provides an excellent base for heavy buildings. In areas where the soil is shifty or weak, foundation contractors usually drive piers into the bedrock to bolster the foundation. 

Wind Deposits 

Wind can also wear away the soil surface (abrasion) or carry with it fine particles of silt and clay from the ground. These deposits are known as loess. With time, the deposit can become thick. Such soils are fertile and used for farming. 

Glacial Deposits 

When a glacier recedes, it can deposit drift along the land surface, including different rock materials, ranging from small clay sediments to unsorted rock debris, and sand, gravel, and coarse particles. These rock materials can form soil layers that can aid construction. Some of the deposits are washed away by running water and deposited in lakes. It’s good to identify the type of soil formation on the ground before you start any construction work. 

Erosion Soil 

Wind, ice, and running water can dislodge surface soils, especially topsoil, and move them away. Over time, these forces can lead to weathering. Erosion often leads to soil degradation with the most common being the loss of nutrients and organisms that help hold the soil layers in place. 

Lucky for you, there are many ways to stop soil erosion before it damages your foundation or interferes with ongoing construction. Landscaping and stabilizing the slope in your land are two of the recommended techniques. If your home’s foundation rests on top of unstable soils, it will settle within no time. This can lead to cracks and other structural problems that can make your home unsafe. Complete Basement Systems can help you stabilize the foundation so it can support your entire house as it’s supposed to. To get started, schedule a free foundation repair inspection today.

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