The answers to the clues below will have something in common.

1. Lower slopes
2. Boondocks
3. Stream sources
4. Isthmus
5. Seneca, Cayuga et al.
6. Delta
7. Marine extension

Answers:

1. FOOThills
2. BACKcountry
3. HEADwaters
4. NECK of land
5. FINGER Lakes
6. MOUTH of a river
7. ARM of the sea

Credit: Chicago Tribune Crossword
Bill Swain
HUMAN GEOGRAPHY