Understanding Deep Valleys and Slopes

The question asks us to identify the term for a deep valley characterized by steep, step-like slopes. Let's look at the options provided and their definitions in the context of geographical features formed by erosion.

Analyzing the Options for Deep Valleys

We are given four terms for different types of valleys:

• U-shaped valley: These valleys are typically formed by glacial erosion. They have a characteristic U-shape cross-section with relatively flat bottoms and steep sides, but not usually described as having "step-like" slopes in the same way as the feature in the question.
• Blind valley: This is a karst landform. A blind valley ends abruptly where the stream that formed it disappears underground into a sinkhole. While they can be deep, the defining characteristic is the sudden termination, not specifically the step-like nature of the slopes.
• Gorge: A gorge is a narrow valley with steep, rocky walls, often carved by a river. While gorges have steep slopes and are deep, the term "step-like slope" is more specifically associated with layered rock structures where differential erosion creates terraces or steps.
• Canyon: A canyon is a deep, narrow valley with very steep sides, often carved by a river over geological timescales. Canyons are frequently found in arid or semi-arid regions where rivers cut through layered rock formations. The differential erosion of harder and softer rock layers often results in the formation of prominent steps or benches along the valley sides, fitting the description of "steep step-like slope".

Identifying the Correct Valley Type

Based on the descriptions, the term that best fits a "deep valley characterized by steep step-like slope" is a canyon. The step-like appearance is a key feature of many canyons, resulting from rivers cutting through horizontal layers of rock with varying resistance to erosion.

Therefore, a deep valley with steep step-like slopes is known as a canyon.

Revision Table: Valley Types

Additional Information on Canyon Formation

Canyons are often formed in areas with uplift and where a river has sufficient power to cut down through the rock layers faster than erosion can widen the valley. The step-like slopes are a direct result of the geology:

• Harder, more resistant rock layers form cliffs or steep steps.
• Softer, less resistant rock layers erode more quickly, forming gentler slopes or benches between the steps.

Famous examples of canyons include the Grand Canyon in the United States, which perfectly illustrates the deep valley and prominent step-like slopes formed by the Colorado River cutting through vast layers of sedimentary rock.