What Are Soil Layers?

From geography classes, we know that the earth has different types of layers. These layers form over time and differ in composition. Depending on the composition of each layer, some are suitable for construction while others are not. Let’s break down the different types of soil layers including their composition and load-bearing capacity. 

What Are Soil Layers? 

Generally, the soil beneath the ground contains different strata. Each layer has different properties. The deeper you go the denser the soil layers become. 

In most locations, the top layer consists of organic matter that supports plants and other vegetation. Below that layer, you may find clay, silt, and sandy soils depending on where you live. After this layer is the bedrock, which consists of very stable and dense soil. 

When building a house, you must consider the properties of the different soil layers. This includes their bearing capacity and settlement. Otherwise, your foundation is bound to fail if the load above it exceeds the soil layer’s bearing capacity. 

Type of Soil Layers 

Soil comes in many different layers. The most common include: 

Fill Soil 

This layer consists of man-made deposits. Due to the increasing number of constructions going on, soils for building foundations are quickly becoming scarce. To cater to this scarcity, contractors are using soil from other sites to create a strong base for their foundation. This soil is what is known as fill soil. 

Fill soil also comes in handy on sites that contain high amounts of expansive clay soils. Builders opt to remove the expansive soils and replace them with compacted fill soils. Fill soil contains a mixture of sand, rocks, stone, and earth which provides a sturdy base for construction work. 

Due to its strength and stability, fill soil is mostly used for large construction projects and landscaping. It is ideal for leveling up the ground and fixing water drainage issues. It also secures the ground and retains walls. 

Glacial Deposits 

Sometimes, receding glaciers move over solid rock carrying sediments with it. The result is a layer of soil that is solid and incompressible. Such a layer usually contains various soil particles such as gravel, sand, silt, clay, and boulder-sized particles. 

If the glacial deposit is too dry, it easily disintegrates. It is also worth knowing that the deposited materials are densely packed and impermeable. In other words, they can’t drain water. Structures built on glacial deposits are less likely to experience extreme settlement. 

Bedrock 

Deep down the earth lies a compact mass of virgin rock that’s known as the bedrock. This layer is impervious and immune to changes in moisture that would otherwise affect the soil above. As well as being weather-resistant, the bedrock has a superb load-bearing capacity. This layer acts as an anchor for piers that are driven to the ground to support a settling foundation. 

Erosion Soil 

Sometimes, water, wind, and ice remove topsoil and deposit them in a different place. This soil is generally weak and incapable of supporting the weight of your structure, leading to foundation settlement as it lacks nutrients and particles that hold the soil layer together. 

The soil loss can be damaging to your home especially if it affects your foundation. Also, eroded soil is shifty and unlikely to support your structure. As a result, your home may suffer bowing walls, cracks, and lessening stability. 

You can curb erosion through intelligent landscaping. This entails planting trees, grass, and bushes around your home to hold the topsoil in place. Slope stabilization also provides a lasting solution to foundation settlement caused by erosion. 

If your foundation is shifting due to settlement or shrinking soils, contact Tar Heel Basement Systems for a free foundation inspection and repair quote. We can help you stabilize it so it can properly support your home. 

Holly Richards-Purpura

Content Writer

Holly is a Content Writer for Groundworks who has written and edited web content for the foundation services industry for almost 10 years. With a background in journalism, her passion for the written word runs deep. Holly lives in Columbus, OH, with her husband. Along with educating homeowners, she also has a big heart for the Big Apple.