WORD SPIRAL

Starting from 1, fill in the grid clockwise with four-letter words. The last letter of each word becomes the first letter of the next to reveal a geographical term. 1. Male monarch 2. Silent, sullen 3. The Red Planet 4. Offscourings 5. Castle surround 6. Amphibian 7. Delicatessen, in short 8. Article 9. Sail support 10. Ballet skirt 11. Employs 12. Counterfoil 13. Gaffer 14. House type 15. Mosque prayer leader 16. Night insect