This article was written
especially for "Crain's Petrophysical Handbook"
by E. R. Crain,
P.Eng in 2007. This
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Coding Lithology on Plots
Both hand drawn and computer drawn plots may be coded with symbols
to represent various rock types and accessory information. The
recommended codes and colours are given in the illustrations
below. Some symbols
and codes must be simplified for computer use, and the coding
or shading should be identified in a legend on each plot or diagram.
For a complete list of
abbreviations and symbols used in geological sample descriptions,
see This List.
Lithology codes as displayed on a modern
computer drawn strip log. Older strip logs are black and white
illustrations but colour may be added by hand.
Lithology CODES IN PETROPHYSICAL SOFTWARE
coding on petrophysical analysis depth plots is less detailed than
on sample description logs. The codes are somewhat limited by the
software designer but the colours are usually under user control.
codes from a modern petrophysical software package
Log analysis lithology plot (left) in a complex sequence, and sample
description plot (right) over the same interval.