ravine
Pass
ravine
Try to find pictures of canyons on the web. Basically a canyon is a steep-sided valley. The word is used principally in North America.
In Welsh, the "w" is pronounced "oo". So cwm is pronounced "coom".
Hole, well, chasm, crack, crater, pit.
That would be CANYON.
A "fissure" is a crack or break in something. You might use the word "fissure' to describe a steep-sided canyon, something that looks like a crack in the mountain. You would not use "fissure" to describe the mountain itself.
Sharp or Steep?
Steep as a verb: dunk, soak.Steep as an adjective: high, bold.
wall
scarp
hexagonal