What does the presence of significant cliffs indicate about fjords?

The presence of significant cliffs indicates that fjords are deeply indented into coastlines. Fjords are formed by glacial activity, which carves out deep, narrow inlets with steep sides. These cliffs are a result of the geological processes that shape fjords, leading to their distinctive steep and rugged profiles. As glaciers retreat, these valleys are flooded by the sea, creating the dramatic landscapes that fjords are known for.

The other options do not accurately describe the characteristics of fjords. For instance, fjords are typically deep rather than shallow, and their unique geography sometimes poses navigation challenges rather than ensuring safety. Additionally, they often have narrow openings to the ocean rather than wide ones, which further emphasizes their deeply indented nature. Thus, the cliffs serve as a clear indication of the fjord’s depth and the extent of its geographical features.