Hill Slope Elements: Ridge to Valley Order

A standard hillslope profile exhibits a characteristic sequence of elements from the ridge crest down to the valley floor. This sequence represents the typical evolution and form of a landscape under various geomorphic processes.

Understanding the Sequence

• Convex slope (C): This is the uppermost part of the slope, located near the ridge. It typically has an outward curve, formed by weathering and erosion processes near the crest.
• Free-face slope (A): Situated below the convex slope, this is a steep section often characterized by exposed rock or a near-vertical drop. It forms where erosion outpaces weathering, exposing resistant rock layers.
• Rectilinear slope (D): Found below the free-face or convex element, this is a straight, uniform slope. It often represents an intermediate stage or a balance between erosional forces.
• Concave slope (B): This is the lowest part of the slope, leading into the valley. It has an inward curve, where eroded material accumulates and processes like soil creep are dominant.

Determining the Correct Order

Arranging these elements from the highest point (ridge) to the lowest point (valley) yields the following sequence:

1. Convex slope (C) - Ridge crest
2. Free-face slope (A) - Below convex
3. Rectilinear slope (D) - Below free-face
4. Concave slope (B) - Valley floor

Thus, the correct order is C, A, D, B.