Therefore, Table 5 (Reference 4, unpublished work by Ayers and Plum) is
provided for a more useful classification of organic soils.
For the characteristics of the Unified Soil Classification System
pertinent to roads and airfields, see NAVFAC DM-5.4.
3. TYPICAL PROPERTIES. Some typical properties of soils classified by
the Unified System are provided in Table 6 (Reference 5, Basic Soils
Engineering, by Hough). More accurate estimates should be based on
laboratory and/or field testing, and engineering evaluation.
ROCK CLASSIFICATION AND PROPERTIES
1. VISUAL CLASSIFICATION.
Describe the rock sample in the following
a. Weathering Classification. Describe as fresh, slightly weathered,
etc. in accordance with Table 7 (Reference 6, Suggested Methods of the
Description of Rock Masses, Joints and Discontinuities, by ISRM Working
b. Discontinuity Classification. Describe spacing of discontinuities
as close, wide, etc., in accordance with Table 8. In describing structural
features, describe rock mass as thickly bedded or thinly bedded, in
accordance with Table 8. Depending on project requirements, identify the
form of joint (stepped, smooth, undulating, planar, etc.), its dip (in
degrees), its surface (rough, smooth, slickensided), its opening (giving
width), and its filling (none, sand, clay, breccia, etc.).
c. Color and Grain Size. Describe with respect to basic colors on rock
color chart (Reference 7, Rock Color Chart, by Geological Society of
America). Use the following term to describe grain size:
coarse-grained - grain diameter >5mm
medium-grained - grain diameter 1 - 5mm
fine-grained - grain diameter <1mm
aphanitic - grain size is too small to be perceived by unaided
glassy - no grain form can be distinguished.
(2) For Sedimentary Rocks
coarse-grained - grain diameter >2mm
medium-grained - grain diameter = 0.06 - 2mm