Hanging Valley - A Tributary Valley high above the main valley 

To remember the meaning of the term Hanging Valley, use the following mnemonic:

The hanging valley could be seen high up above the main valley she was in.

A hanging valley is a tributary valley to the main glacier, too cold and high up for ice to move easily. It's therefore not eroded as much as the lower main valley, and is often the site of a waterfall crashing several hundred metres to the main valley floor.