Why do blind valleys end at cliffs in karst landscapes?

In karst landscapes, blind valleys end at cliffs because of the way surface drainage interacts with subsurface cave systems.

As a stream valley cuts into soluble limestone, water begins to drain into the rock through joints and fractures, which gradually enlarge into underground passages. Over time, these passages become large enough to capture the entire flow of the surface stream. When this happens, the surface channel downstream of the point where the water sinks—often called a "swallow hole"—becomes a dry valley that no longer deepens.

Upstream from these swallow holes, the tributary valleys continue to erode and deepen their channels. This process creates a blind valley that terminates abruptly at a cliff, where the stream disappears underground. The top of this cliff typically aligns with the abandoned, higher floor of the dry valley.1