Soil Survey of Murray and Whitfield Counties, Georgia

Murray and Whitfield Counties, Georgia 223
The soils in Whitfield County and in the western two-thirds of Murray County formed
under a thermic temperature regime; that is, the mean soil temperature at a depth of
about 20 inches is 59 to 72 degrees F. The soils in the eastern third of Murray County
formed under a mesic temperature regime in which the mean soil temperature at a
depth of about 20 inches is 46 to 59 degrees F. The rate of chemical reactions and
other processes in the soil depends to some extent on temperature. In addition,
temperature affects the type and quantity of vegetation, the amount and kind of
organic matter, and the rate at which the organic matter decomposes. Soils in the
cooler areas on north-facing slopes, such as the Cheoah soils, generally have a higher
content of organic matter than soils in the warmer areas on south-facing slopes, such
as the Edneytown and Pigeonroost soils.
Relief
Relief is the elevations, or inequalities, of the land surface considered collectively.
The color of the soil, the degree of wetness, the thickness of the A horizon, the content
of organic matter, and the plant cover are commonly related to relief. In Murray and
Whitfield Counties, the most obvious effects of relief are those that relate to the color
of the soil and the degree of wetness.
Fullerton and Dewey soils have a mainly reddish subsoil, whereas the subsoil of
Chenneby soils is mottled primarily in shades of brown and gray. This difference in
color results from a difference in relief and a corresponding difference in internal
drainage. Fullerton and Dewey soils are in the higher positions on the landscape and
are better drained than other soils; therefore, the soil material is better oxidized and
the subsoil is reddish.
Time
The length of time that the soil-forming processes have acted on the parent material
helps to determine the characteristics of the soil. Determinations of when soil
formation began in the survey area are not exact. Most of the soils are considered
mature. Mature soils are in equilibrium with the environment. They are characterized
by readily recognizable pedogenic horizons and a regular decrease in content of
carbon with increasing depth. Some areas of upland soils are on rather broad, stable
landscapes where the soil-forming processes have been active for thousands of years.
These mature soils have a highly weathered solum and a well expressed zone of
illuviation.
Chenneby soils receive sediment annually from floodwater. These soils are
characterized by an irregular decrease in content of carbon with increasing depth.
These young soils are not as highly developed as older terrace soils or upland soils
that have been exposed to soil-forming process for a longer period of time.
Processes of Horizon Differentiation
The results of the soil-forming processes are evidenced by the different layers, or
soil horizons, in a profile. The soil profile extends from the surface down to materials
that are little altered by the soil-forming processes.
Most soils have three major horizons—the A, B, and C horizons. Some soils,
particularly those in forests, also have an O (organic) horizon at the surface. This
horizon is an accumulation of organic material, such as twigs and leaves, or of
humified organic material that has little admixture of mineral material. The major
horizons can be subdivided to indicate differences within the horizon. For example, the
Bt horizon has an accumulation of clay from overlying horizons and represents the
best developed part of a B horizon. Nella soils, for example, have a Bt horizon.