There in the black mudstone beneath your feet, black bones are visible. Bones of creatures who once ruled the Earth but died in fear, pain, and exhaustion. Bones preserved by the geologic processes of fossilization. Groundwater passing through them, trading inorganic minerals for organic marrow. The slow accumulation of thousands of feet of sediment bothers them not at all.
Seas cover the land and then retreat.
The bones remain indifferent. The Earth's crust shifts and the San Rafael Swell starts to form. The bones do not care. But with that swelling comes erosion. The thousands of feet of sediment disappear and one day a sheepherder stumbles across a large black bone.