I don't know where South Valley is. George A. Blake lived in Bernalillo County when he listed himself as retired. He was a census taker in 1920. If I can find those notes, I will verify that he was listed earlier as a miner. However, I found another Blake in AZ who listed himself as a miner, and he owned several mines. So, Geo. A. may have owned a mine in the vicinity of Blake Road. Do you know whether there were mines in that area in the late 1800's? It is also possible that he and his family lived on that road when it was relatively uninhabited, and the post office named the road for them.That used to be done in rural areas because most residents knew where certain families lived and thus would give directions by naming the families that lived on that road.