It is a massive block ... Sitting underground in Death Valley, it has no obvoius purpose, and I think it was located by satellite GPRadar .. finding the cavity it also found the irregular presence of the huge rectangular stone ( the GPR of the mineral hunters is a powerful item, I'm thinking).
I do not recall the main subject of the article, I think perhaps it dealt with Death Valley in general, and I came upon it after reading about the irrigated food terraces near Lake Titicaca etc, which at 12,000 feet high are rendered mostly useless. This is little help, I fear. Though the agriculture post was here on GHMB.
I am not recalling anything else except looking for diamonds -- kimber-pipe --- with GPR, and it is just another association of that day.
I am of the opinion that there are many things underground of which we know little or nothing!!
I am also of the opinion that some mentalities exist which well know how to handle planetary maintenance issues of great scope, like hiding the works of one civilization from their "competition" ... so to speak.
I will wish you good hunting, if that helps.
Mind is the rider.