Environmental Engineering Reference
In-Depth Information
90
FIGURE 6.12
Equatorial equal-area stereo-net (Lambert projection or Schmidt net). (From Hoek, E. and Bray, J. W., Rock Slope
Engineering, 2nd ed., Institute of Mining and Metallurgy, London, 1977. With permission.)
6.2.2
Igneous Rocks
Formation Types
Igneous rocks are grouped on the basis of origin as intrusive or extrusive, and their
formational types are defined according to shape and size as batholiths, stocks,
laccoliths, etc. The characteristics of the various types are described in Table 6.3 and
illustrated in Figure 6.15. Examples of dikes and sills are illustrated in Figures 6.16
and 6.17, respectively. Associated rock types for the various igneous bodies are given in
Table 6.4.
Landforms
The general surface expression of the various igneous formations is described in Table 6.3.
An example of a batholith is illustrated on the topographic map given in Figure 6.18 and
dikes are illustrated on the topographic map given in Figure 6.19, Figure 2.5, Figure 2.6
and Figure 2.10. Differential erosion of weaker formations around a stock may leave a
monadnock as shown in the topographic map given in Figure 6.73.
 
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