FIOPY ANAGRAMS

Each of the words below can be anagrammed into a new one when one of the following letters is inserted into it. Each letter is used once, and all the new words are related.

F I O P Y

1. STEEP

2. RAVEN

3. STORE

4. ALONG

5. SERGE

HINT:
All the new words are geographical terms.

Answers:

1. STEPPE

2. RAVINE

3. FOREST

4. LAGOON

5. GEYSER