Curious. Is that all the deeper it is or does it get deeper?
The definitition of a slot canyon is an extremely deep and narrow canyon with vertical walls. Often, all one sees of a slot canyon from up top is a narrow crack in the ground one can jump or even walk across but will go down as much as 100'. Sometimes they will stay that narrow. Often they will widen out as they get deeper. They are very common in northern AZ and southern Utah.
One of the best known and certainly one of the most spectacular is Antelope Canyon in northeastern AZ.
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here to see more pics.