In accordance with this general trait of the mountain system, the beginnings of the barrancas in the east are generally slight, but they quickly grow deeper, and before they disappear in the lowlands of Sinaloa they sometimes reach a depth of from 4,000 to 5,000 feet.

Of course, they do not continue equally narrow throughout their entire length, but open up gradually and become wider and less steep.
Besides these large barrancas, which impede the traveller in the highlands and necessitate a course toward the east, there are innumerable smaller ones, especially in the western part of the range, where large portions of the country are broken up into a mass of stupendous, rock-walled ridges and all but bottomless chasms.

A river generally flows in the barrancas between narrow banks, which occasionally disappear alltogether, leaving the water to rush between abruptly ascending mountain sides.
As far as the first of the large barrancas was concerned, near the top of which we were standing, we could for some little distance follow its windings toward the west, and its several tributaries could be made out in the landscape by the contours of the ridges.

Barranca de Cobre is known in its course by different names.

Near the mine of Urique (the Tarahumare word for barranca), it is called Barranca de Urique, and here its yawning chasm is over 4,000 feet deep.