It is a dirt floor. Yes, it is odd. It is supposed to represent the mixture of species that lived in Pleistocene California 10,000 years ago when there were native camel, llama, and pronghorn species living together in the California grasslands.
I honestly don't know, but they have been together since 2009ish so I assume it must be okay. Maybe one of the San Diego Zoo regulars like Betsy or washaw can provide more specific commentary on it...
