Environmental Engineering Reference
In-Depth Information
72-108
54-71
36-53
6-17
6-17
18-35
0-5
0-5
6-17
0-5
FIGURE 7.110
Approximate maximum depth of frost penetration in the United States given in inches. (From HRB, HRB
Special Report No. 1, Pub. 211, National Academy of Sciences-National Research Council, Washington, DC,
1952. Adapted with permission of the Transportation Research Board.)
and floors in unheated buildings must be protected from freezing during the winter
months, otherwise substantial deflections will result from subsequent thawing during
warm weather.
7.8
Pedological Soils and Plant Indicators
7.8.1
Introduction
Pedology
Although defined as a pure soil science (Rice, 1954; Hunt, 1972), pedology is commonly
recognized as the science that studies soils primarily from an agricultural perspective.
Soils, to a pedologist or soil scientist, are “a collection of natural bodies on the Earth's sur-
face, containing living matter, and capable of supporting plants” (SCS, 1960).
Pedological information provides much useful data to the geologist and engineer,
although in general the information pertains basically to depths within a few feet of the
surface. It is available in the form of detailed maps and reports published by the Soil
Conservation Service of the U.S. Department of Agriculture.
Modern Soils: The Soil Profile
Soil scientists have divided the modern soil profile into three major morphological units,
referred to as horizons, as shown in
Figure 7.111.
The A (or O), B, and C horizons repre-
sent weathering zones and the D or R horizon represents unweathered parent materials.
As water filters through the upper zone of plant debris and decayed organic matter, weak
organic acids are formed. The weak acids and percolating water remove material from the
zone beneath the organic layer and redeposit it at some depth below.
