Geology Reference
In-Depth Information
(9) Structure —Describe the structure of intact soils in accordance
with the criteria in Table 3-7.
Table 3-7
Criteria for Describing Structure [1]
Description
Criteria
Stratified Alternating layers of varying material or color with
layers at least 6 mm thick; note thickness
Laminated Alternating layers of varying material or color with
the layers less than 6 mm thick; note thickness
Fissured
Breaks along definite planes of fracture with little
resistance to fracturing
Slickensided
Fracture planes appear polished or glossy, sometimes
striated
Blocky
Cohesive soil that can be broken down into small
angular lumps which resist further breakdown
Lensed
Inclusion of small pockets of different soils, such as
small lenses of sand scattered through a mass of
clay; note thickness
Homogeneous
Same color and appearance throughout
(10) Range of Particle Sizes —For gravel and sand components,
describe the range of particle sizes within each component as de-
fined in (3) and (7) in the “Definitions” section. For example, about
20% fine to coarse gravel, about 40% fine to coarse sand.
(11) Maximum Particle Size —Describe the maximum particle size
found in the sample in accordance with the following information:
(11.1) Sand Size —If the maximum particle size is a sand size,
describe as fine, medium, or coarse as defined in (7) in the “Defini-
tions” section. For example, maximum particle size, medium sand.
(11.2) Gravel Size —If the maximum particle size is a gravel size,
describe the maximum particle size as the smallest sieve opening that
the particle will pass. For example, maximum particle size, 1 1 2 in. (will
pass a 1 1 2 -in. square opening but not a 3 4 -in. square opening).
(11.3) Cobble or Boulder Size —If the maximum particle size is a
cobble or boulder size, describe the maximum dimension of the
largest particle. For example, maximum dimension, 18 in. (450 mm).
(12) Hardness —Describe the hardness of coarse sand and larger
particles as hard, or state what happens when the particles are hit
by a hammer; for example, gravel-size particles fracture with con-
siderable hammer blow, some gravel-size particles crumble with
hammer blow. “Hard” means particles do not crack, fracture, or
crumble under a hammer blow.
(13) Additional comments shall be noted, such as the presence of
roots or root holes, difficulty in drilling or augering hole, caving of
trench or hole, or the presence of mica.
(14) A local or commercial name or a geologic interpretation of the
soil, or both, may be added if identified as such.
(15) A classification or identification of the soil in accordance with
other classification systems may be added if identified as such.
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