Learned this as a child at Henderson's Camp on Lopez Island (one of the San Juan Islands in the Straights of Juan de Fuca)about forty years ago.I remember part of the tune, & the words I remember go like this:

I ride to the canyon wall,
To the place where the river did fall,
But now on the valley floor
Lies an Indian Sea from shore to shore.

It's a beautiful haunting melody, and I'd love to know the rest rest of it.