11.
The dark color here is caused by carbonized remains from the plants which grew in the ancient swamps. Coal is formed in much the same way, but there is too much inorganic material in this seam to produce coal. This is the coal-like seam mentioned at [No. 7]. On the very top, the dirt is from the Mancos formation of Cretaceous age, and is composed of marine shales deposited in the ancient sea which covered the area. It was originally much thicker, and is younger than any of the other rocks exposed here.
Immediately ahead and extending to the right for nearly 300 feet is the ruin called Atsinna, a Zuñi word referring to the “writing on rock.”