Soil Survey of Jackson County, Texas Page: 89
vii, 147, [2] p., 50 folded p. of plates : ill., maps (some col.) ; 28 cm.View a full description of this book.
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89
Formation of the Soils
In this section the factors of soil formation are related
to the formation of the soils in Jackson County. Also,
processes of horizon differentiation and the surface
geology of the county are described.
Factors of Soil Formation
Soil is formed by the action of soil-forming processes
on material deposited or accumulated by geological
forces. The characteristics of a soil depend on the
physical and mineralogical composition of the parent
material, the climate under which the soil material has
accumulated and has existed since accumulation, the
plant and animal life on and in the soil, the relief, and
the length of time the forces of soil development have
acted on the soil material.
Climate and living organisms are active factors of soil
formation. They act on the parent material that has
accumulated through the weathering of rocks and slowly
change it into a natural body that has genetically related
horizons. The effects of climate and living organisms
are conditioned by relief. The parent material affects the
kind of soil profile that forms and, in extreme cases,
determines it almost entirely. Finally, time is needed for
changing the parent material into soil. Generally, a long
time is needed for the development of distinct horizons.
The factors of soil formation are so closely
interrelated in their effects on the soil that few
generalizations can be made regarding the effect of any
one factor unless conditions are specified for the other
factors.
Parent Material
Parent material is the unconsolidated mass in which
a soil forms. It affects the chemical and mineral
composition of the soil. The parent material in Jackson
County consists of loamy and clayey sediments
deposited by ancient streams and rivers. Some of the
loamy and clayey sediments have been reworked and
modified by the wind. Some areas have windblown
sands. The geology of the parent material is described
in the section "Surface Geology."Climate
Precipitation, temperature, and wind have had a
major effect on the formation of soils in Jackson
County.
Wetter or drier climates in the past had an effect on
how parent material was deposited. The climate was
drier when the sandy parent material of the Kuy and
Rupley soils was deposited by wind. The climate was
similar to the present one when the loamy and clayey
parent material of the Dacosta and Laewest soils was
deposited by rivers.
Jackson County has a humid subtropical climate. The
climate is uniform throughout the county. The dominant
climatic influence on soil formation has been
precipitation, which has caused the translocation of
carbonates and clays. The moderate amount of rainfall
has resulted in moderately rapid soil formation.
Plant and Animal Life
Plants, micro-organisms, earthworms, and other
living organisims have contributed to the formation of
the soils. They provide organic matter, help to
decompose plant residue, influence the chemistry of the
soil, and contribute to soil development. Gains in
content of organic matter and nitrogen in the soil, gains
and losses in plant nutrients, and changes in structure
and porosity are caused by plants and animals.
The dominant native vegetation in most of the county
consisted of prairie plants. Soils that formed under this
vegetation, such as Dacosta, Laewest, and Texana
soils, have a dark-colored surface layer that contains an
appreciable amount of organic matter. In some parts of
the county, however, the native vegetation was
dominantly woody plants. Soils that formed under these
plants, such as Morales and Kuy soils, have a lighter
colored surface layer that has less organic matter than
the soils that formed under prairie vegetation.
Relief
Relief influences soil development through its effect
on drainage and runoff. If other factors are equal, the
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Miller, Wesley L. Soil Survey of Jackson County, Texas, book, May 1997; Washington D.C.. (https://texashistory.unt.edu/ark:/67531/metapth224539/m1/99/: accessed March 28, 2024), University of North Texas Libraries, The Portal to Texas History, https://texashistory.unt.edu; crediting UNT Libraries Government Documents Department.