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Exploring Types of Bedrock on Land



Curiosity often leads us to wonder about the mysteries hidden beneath the surface of our property. While we may be familiar with the landscape above ground, there’s a whole world of rock formations beneath our feet. Bedrock, the solid foundation upon which our land rests, holds crucial information about our surroundings.


As landowners, it’s essential to gain knowledge of the bedrock present on our property. By understanding the different types of bedrock and their implications, you can make informed decisions regarding construction, water resources, and natural hazards, safeguarding your investments and the well-being of your land.


Understanding Bedrock on Land

When we hear the term "bedrock," we often envision solid, unyielding rock deep beneath the surface. This perception is accurate, as bedrock is the consolidated rock layer that underlies soil, sediments, and other loose materials. It forms through geological processes such as cooling and solidification of molten rock (igneous), deposition and compaction of sediments (sedimentary), or the transformation of existing rock due to heat and pressure (metamorphic). By comprehending the formation and characteristics of bedrock, we can begin to appreciate its significance in shaping our landscapes. Mineral resources can be found within bedrock and different bedrock types will harbor different rocks and minerals that can be sourced. There are three main layers of bedrock that can carry specific rocks and minerals that can be mined from below the Earth’s surface:

  • Igneous bedrock

  • Sedimentary bedrock

  • Metamorphic bedrock

Landowners should understand what is below their properties surface if they are interested in potential mining leases. LandGate provides landowners with mineral data using a geologic map showing what rock types are below.


Types of Bedrock & Their Minerals

The world of bedrock is diverse, comprising various types that can be classified into three major categories: igneous, sedimentary, and metamorphic.

  • Igneous bedrock originates from the cooling and solidification of magma or lava.

  • Sedimentary bedrock forms from the accumulation and compaction of sediments over time.

  • Metamorphic bedrock undergoes profound transformations due to heat and pressure.

Each type of bedrock possesses unique properties that influence the geological, physical, and chemical characteristics of the land. Igneous Bedrock Igneous bedrock contains a wide variety of minerals that chemical composition depends on the cooling conditions. Granite and basalt are common minerals found here. Granite is composed of quartz, feldspar, and mica mainly but can also contain hornblende, biotite, or muscovite. Granite is commonly known for being used for countertops and flooring. But is also used in various monument and memorial structures and landscaping projects.

  • Granite with high silica content can be used in the production of glass and ceramics in its most raw form.

Basalt contains minerals such as plagioclase feldspar, pyroxene, and olivine. Basalt is most commonly used in construction materials, stone wool production, landscaping, and industrial applications. Basalt is typically crushed and used as an aggregate in concrete and asphalt due to its high strength and durability.

  • In use cases like landscaping and industrial use - it's a preferred material because it provides resistance to heat and chemicals.

Sedimentary Bedrock Sedimentary bedrock is composed of sediments that have been compacted and cemented by pressure overtime. Limestone, sandstone, and shale are common minerals found here. Limestone consists mainly of mineral calcite and sometimes contains clay minerals too. It is used for construction, cement and lime production, and agriculture. Similarly to basalt, limestone is a key ingredient in road, sidewalk, and building construction. It provides stability, durability, and drainage properties that construction projects require.

  • For agriculture, agricultural lime is crushed limestone that is added to soil to neutralize acidity and provide essential calcium and magnesium nutrients for plant growth.

Sandstone is mainly sand-sized grains of quartz and other minerals like feldspar, lithic fragments, or clay minerals. Sandstone is commonly used for the creation of dimension stone. Dimension stone is high quality sandstone blocks that can be quarried and used for architectural purposes for sculptures, monuments, and ornamental features.

  • If the sandstone has high silica content, it can be used for glassmaking and in ceramic industries.

Shale is a fine-grained sedimentary rock composed of clay minerals. Shale is widely known for its significant role in the extraction of oil and natural gas through hydraulic fracturing. Fracking is the process of shale being drilled, and a high-pressure fluid is injected to release trapped hydrocarbons. Metamorphic Bedrock Metamorphic rock forms from the transformation of existing rock under heat and pressure. The minerals present in metamorphic bedrock depend on the parent rock and the degree of metamorphism. Marble and slate are commonly found here. Marble is primarily composed of recrystallized calcite or dolomite. Marble is a popular material used for building, sculpture, monuments, and interior design. It is very durable, timeless, and has the ability to retain a polished finish. Slate is a fine-grained metamorphic rock that is derived from shale and mainly consists of clay minerals. Different from shale, slate is used for roofing tiles, flooring, writing boards, and billiards tables. Slate has a low porosity, non-slip surface which is why it works well for flooring both interior and exterior spaces.


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