Geology Reference
In-Depth Information
Fig. 10.13.
Compatibility of geological
contacts in outcrop. a Geo-
logical map of the southern
Sequatchie anticline at Blount
Springs, Alabama on a 30 m
DEM base from Fig. 2.4. Ob-
lique view to NE. Distance
between grid lines, 1 km.
Thick black lines are geologic
contacts. b Composite struc-
ture contour map of the top
Mtfp, oblique view to NE (from
Fig. 3.23b)
A composite surface map (Sect. 3.6.2) provides a method for the simultaneous testing
of a complete geological map for internal consistency. It is very difficult to determine by
inspection alone whether the outcrop traces on a geological map (e.g., Fig. 10.13a) are
consistent with one another. The composite surface map of a representative horizon pro-
vides such a test. If the composite-surface map shows a realistic structure, without unex-
plained peaks and valleys, as in Fig. 10.13b, then the combined data are internally consis-
tent. Because outcrop trace locations, dips and thicknesses all work together to produce
the final map, all of this information is tested by the composite surface map.
10.4.2
Compatibility of Thicknesses on Cross Sections
A cross section is a powerful tool for checking and improving the structural interpreta-
tion presented on an outcrop map or on multiple structure contour maps. First be sure
the cross section matches the map from which it was constructed. In section view, poorly
controlled map horizons may be improved with information from other horizons
(c.f. Sect. 6.4). Errors in mapping on one horizon can be recognized as incompatibilities
with the geometry of horizons above or below. Many of the mapping pitfalls noted pre-
Search WWH ::




Custom Search