Slope Landforms

Generally, when discussing slope, we are primarily concerned with hillslopes—that is, the slopes connecting hilltops with river channels in valley bottoms. Slopes include slopes created by river sediments, rainwash, and rockfall (talus). Although discussed in detail later in the text, it should be pointed out that slope has a great influence on mass movement and wasting. Slope not only influences the evolution of landforms but also gives geologists important information about the formation of landforms. Slope landforms include the following:

• alas—a steep-sided depression formed by the melting of permafrost; it may contain a lake.

• defile—a narrow pass or gorge between mountains or hills.

• dell—a small wooded valley.

• escarpment—a transition zone between different provinces that involves a sharp, steep elevation differential, characterized by a cliff or steep slope.

• glen—a valley, typically one that is long, deep, and often glacially U-shaped.

• gully—a landform created by running water eroding sharply into soil, typically on a hillside.

• hill—a landform that extends above the surrounding terrain, in a limited area.

• knoll—a small, natural hill.

• mountain pass—a saddle point in between two areas of higher elevation.

• ravine—a very small valley, which is often the product of stream-cutting erosion.

• ridge—a geological feature that consists of a continuous, elevational crest for some distance.

• rock shelter—a shallow cavelike opening at the base of a bluff or cliff.

• scree—an accumulation of broken rock fragments at the base of mountain cliffs.

• vale—a wide river valley, with a particularly wide floodplain or flat valley bottom.