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 around the mesa, until I met the river again where it flowed under the south flank.

On that ride I got a better idea of its actual structure. All the way round were the same precipitous cliffs of hard blue rock, but in places it was mixed with a much softer stone. In these soft streaks there were deep dry watercourses which could certainly be climbed as far as they went, but nowhere did they reach to the top of the mesa. The top seemed to be one great slab of very hard rock, lying on the mixed mass of the base like the top of an old-fashioned marble table. The channels worn out by water ran for hundreds of feet up the cliffs, but always stopped under this great rimrock, which projected out over the erosions like a granite shelf. Evidently, it was because of this unbroken top layer that the butte was inaccessible. I rode back to camp that night, convinced that if we ever climbed it, we must take the route the cattle took, through the river and up the one canyon that broke down to water-level.