Undoubtedly they belong to a more recent period than the rude stone structures described before.

Most of the ancient remains of the Sierra are remnants of tribes that expanded here from the lowlands, and only in comparatively recent times have disappeared.

I also perceived that they were built by a tribe of Indians different from those which erected the houses in the caves of the eastern and northern Sierra Madre, and in the country east of it, and may safely be ascribed to Opatas.
In spite of the rest here, the animals did not seem to improve on the grama and buffalo grass.

It was rather perplexing to note that they grew weaker and weaker.

The grass of the sierra, which was now gray, did not seem to contain much nourishment, and it became evident that the sooner we proceeded on our journey, the better.