What landscape feature is created by a glacier and is characterized by steep walls?

A fiord coast, formed by glaciers, is characterized by steep walls that plunge into deep, narrow inlets. When glaciers carve out valleys, they typically do so by eroding the landscape in a U-shaped pattern due to their immense weight and movement. After glaciers retreat, these U-shaped valleys can fill with seawater, creating fiords. The steep sides of fiords result from the erosive power of the glacial ice, which cuts sharply into the rock, leaving behind vertical cliffs.

In contrast, river valleys generally exhibit a V-shape, which is a product of river erosion rather than glacial action. Deltas and alluvial plains are formed by sediment deposition, not by glacial activity. Therefore, a fiord coast is the correct answer, as it exemplifies the striking geological features resulting from glacial processes, including the steep walls formed by intense erosion.