Answer:

MTNS

Answer	Crossword Clue
MTNS	Peaks (abbr.)
MTNS	Rocky hts.
MTNS	They're within a certain range: Abbr.

MTNS	Alps, e.g.: Abbr.
MTNS	Ski areas: Abbr.
MTNS	Atlas abbr.
MTNS	Chain components: Abbr.
MTNS	Parts of ranges: Abbr.
MTNS	The Andes, e.g.: Abbr.
MTNS	High pts.
MTNS	Range components: Abbr.

MTNS	"White" peaks in N.H.
MTNS	Parts of the Rockies: Abbr.
MTNS	Chain letters?
MTNS	Chain links?: Abbr.
MTNS	The Rockies, e.g.: Abbr.
MTNS	The Rockies, e.g. (abbr.)
MTNS	Short range?
MTNS	Great Smokies of N.C.

MTNS	Wash.'s Olympics, e.g.
MTNS	Peaks: Abbr.
MTNS	Atlases, for instance: Abbr.
MTNS	Sierras, e.g.: Abbr.
MTNS	Chain components, for short
MTNS	Gazetteer abbr.
MTNS	The Apennines, for instance: Abbr.
MTNS	Atlas, for example: Abbr.

MTNS	Range makeup: Abbr.
MTNS	St. Elias, in Alaska
MTNS	The Catskills, e.g.: Abbr.
MTNS	The Adirondacks, e.g.: Abbr.
MTNS	Everest and others: Abbr.
MTNS	The Great Smokies, e.g.: Abbr.
MTNS	The Pamirs: Abbr.
MTNS	Abbreviation on maps.

MTNS	Alps or Andes: Abbr.
MTNS	Topographer's abbr.
MTNS	Ranges: Abbr.
MTNS	White and Catskill: Abbr.
MTNS	Rockies, etc.: Abbr.