Figure 1-17. Plunging anticline
(a) Relationship of Topography to Tilted or Folded Interbedded Sedimentary Rocks.
Landforms Developed in Areas of Tilted or Folded Interbedded Sedimentary Rocks. A series
of tilted or nonplunging folds is represented on the surface by a parallel rock outcrop pattern, whereas a plunging
fold is represented by a "zigzag" pattern. Because the various rock types exposed at the surface differ in their
resistance to weathering, the topography in regions of tilted or folded rock takes on a saw-toothed appearance that
is aligned in either a parallel or zigzag pattern respectively (see figures 1-15, 1-16, and 1-17). For example, in
humid climates, the resistant sandstones dominate the topography with sharp parallel ridges and steep side slopes,
while limestone form intermediate slopes, and shale make up the smooth, rounded lowland valleys. In arid
environments, sandstone and limestone form resistant ridges, whereas shales form conical lowland hills.
Drainage Developed in Areas of Tilted or Folded Interbedded Sedimentary Rock. The
alternating ridges and valleys of tilted and folded interbedded sedimentary rock sequences control the trellis
drainage pattern that is prevalent in such regions. The linear stream courses generally follow the lowlands
composed of shale. In humid areas, sag-and-swale-type gullies are formed on both shale and limestone terrane;
steeper-sided, V-shaped gullies may indicate underlying sandstone. In arid environments, residual soils are thin
or nonexistent, so few, if any, gullies exist.
Vegetation in Areas of Tilted or Folded Interbedded Sedimentary Rock. In humid regions,
bands of varying types of vegetation may coincide with the various bands of exposed tilted or folded interbedded
sedimentary rocks. Therefore, the vegetation may appear to have either a parallel or V-shaped pattern, depending
on the extent of folding and/or faulting