When the troughs of tributary glaciers lie above sea level, these hanging valleys

Fjord -  A fjord or fiord is a steep water inlet which is narrow. It is created due to glacial erosion. Long ago, when the earth was covered with glaciers, they cut bedrock into U-shaped valleys. As the glaciers moved, they would leave a narrow waterway in their path, due to melting. These waterways are called fjords.

Limestone, Sandstone, and Shale are all sedimentary rocks so granite is the answer.