I've seen several of these Snow Survey Shelter cabins near high passes in the Easter Sierras. One of the few types of structures allowed in the Wilderness. The cement door step had several names inscribed in the concrete at installation. Dates with the names indicated the door step had been installed in Sept 1971. Obviously the roof and probably much of the wooden structure supporting the roof has been recently replaced. Also cracks in the mortar between the rocks in the wall had been recently resealed with a fresh layer of motor.