N = q+c,/4 for sand and fine to medium gravel and N = q+c,/5 for sand, and
use Figure 1 for describing compactness.
(f) Describe, if possible, appearance and structure such as
angularity, cementation, coatings, and hardness of particles.
(g) Examples of Sample Description:
Medium dense, gray coarse to fine SAND, trace
silt, trace fine gravel (SW). Dry, dense, light
brown coarse to fine SAND, some silt (SM).
(2) Fine-Grained Soils. Soils are identified as fine-grained when
more than half of the particles are finer than No. 200 sieve (as a field
guide, such particles cannot be seen by the naked eye). Fine-grained soils
cannot be visually divided between silt and clay, but are distinguishable by
Identify by estimating
characteristics in Table 3.
(b) Color. Use color that best describes the sample. If two
colors are used, describe both colors. If there are more than two distinct
colors, use multi-colored notation.
Use notations in Table 2.
(d) Appearance and Structure. These are best evaluated at the
time of sampling. Frequently, however, it is not possible to give a
detailed description of undisturbed samples in the field. Secondary
structure in particular may not be recognized until an undisturbed sample
has been examined and tested in the laboratory. On visual inspection, note
the following items:
1) Ordinary appearance, such as color; moisture conditions,
whether dry, moist, or saturated; and visible presence of organic material.
2) Arrangement of constituent materials, whether stratified,
varved, or heterogeneous; and typical dip and thickness of lenses or varves.
3) Secondary structure, such as fractures, fissures,
slickensides, large voids, cementation, or precipitates in fissures or
(e) General Field Behavior.
1) Clays. Clays exhibit a high degree of dry strength in a
small cube allowed to dry, high toughness in a thread rolled out at plastic
limit, and exude little or no water from a small pat shaken in the hand.