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Center for Cedar Glade Studies

Soil, or the Lack of it, in the Glades

To understand why there is so little soil in the glades, we must understand the basic principles of what soil is and how it is formed.

There are several good websites on soil, where you can learn the basics:

  • The Globe project has an excellent site on soil forming factors, and it also has an interesting soil characterization field guide. The field guide includes a test for free carbonates which is relevant to the study of the glades.
  • Fred Moor has an excellent soil site.
  • CARTAGE (Central Array of Relayed Transaction for the Advance of General Education) has a good graphic illustrating soil formation (Search for “soil formation”)

Ninety percent of the solid material in most soil consists of small rock particles. The nature of soil is determined primarily by the size and composition of the rock particles from which it is made.

In middle Tennessee, we find three general types of rock: shale, chert, and limestone.

RockSedimentContribution to Soil
Chert (SiO2)SandSand prevents soil from compacting but doesn’t hold nutrients. 
ShaleClayClay particles tend to be small and are electrically charged. They attract nutrients, which are generally ions in solution, but tend to become compacted.
Limestone (CaCO2)Limestone sand or limestone mud depending on particle size.Limestone sand and mud dissolve rapidly in acid. Soil formed from limestone is, therefore, thin. Limestone’s main contribution to soil is to raise the pH as it dissolves.

As you may have noticed, the Limestone Cedar Glades are generally located in the center of the Nashville Basin. Why is this?

The Nashville Basin is carved out of a series of layers of different kinds of rock. Each kind of rock produces a different kind of soil.

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Middle Tennessee State University
Center for Cedar Glade Studies
Department of Biology 
PO Box 60
Murfreesboro, TN 37132
615.904.8283 (phone for Kim Cleary Sadler)