Geology Reference
In-Depth Information
3.3
Structural Style in Contouring
Contouring may be done using different styles, each of which produces its own char-
acteristic pattern (Handley 1954). With a large amount of evenly spaced data, the differ-
ence between maps produced by different styles will usually be small. Contouring by
any method must be viewed as a preliminary interpretation because unknown struc-
tures can always occur between widely spaced control points. The characteristics of
the common styles of contouring are summarized next. Contours are usually shown as
smooth curves although this should depend on the structural style (Sect. 3.3.4). The
following examples (Figs. 3.1-3.2) are based on exactly the same points in order to
demonstrate the differences that can be achieved by different methods.
Fig. 3.1.
Different contouring methods applied to the same control points (
solid circles
).
a
Equal-spaced
contouring. The dip to be maintained (
heavy contours
) is chosen in the region of tightest control.
b
Parallel
contouring
Fig. 3.2.
Interpretive contouring;
a
based on interpretation that regional trends are northeast-southwest;
b
based on the interpretation that the regional trends are northwest-southeast
