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Soil Layers

Soil layers are deposits that have formed over a long time. Some factors that facilitate the layer deposits include wind, water, glaciers, and human activities such as construction. The layers gain strength and capacity with time. Beneath the layers are bedrocks that keep it even stronger and stable.

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Soil Layers Explained

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. 

What Are Soil Layers?  

Cut out view of soil layers with grass on the top

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 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  

Crumbled loose soil in pile

When a home is constructed, a hole in the ground, slightly larger than the foundation is excavated. Once the foundation is built, the dirt originally found in the hole is packed around the new foundation. Regardless of how well the construction team compresses the soil, this transported dirt is looser and fluffier than the original virgin soil and is more absorbent to water.  

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  

Dry 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 can settle rather quickly. This can lead to cracks and other structural problems that can make your home unsafe. Groundworks 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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