In oceanography, they are usually called "trenches".
a deep, steep-sided, narrow river valley
A deep valley with steep sides would be called a gorge or canyon.
Such a valley would be called a gorge.
Valley
subduction
There are more than one term for a deep narrow valley. Glens, canyons, ravines, fjords are terms you could use.
A canyon is a deep narrow valley.
Canyon
Such structure could be called a Canyon.
the river running through rock wear it down into deep valley with the steep sides what is it called
Canyon
Canyon