This afternoon, the relative quiet was shattered by very loud and very low flying aircraft. They came in fast, from the north east, circled once around the 2 mountains just to the north of us, and set down. CH-47 types. (confirmed) They as in : 4. No one was seen walking over/around the mountains, and it was determined it was in our own best interests not to venture out and introduce ourselves.... After an hour and a half they departed, low and fast, heading back to the north east, just as they arrived. Maybe a training mission? They may have been on BLM land, but we were not going to make a point of asking! Earlier, we were told that 4-6 humvees were seen going over the mountain ridge.... Just to the immediate west of us.... No dust up here ( thank heavens!) all muddy right now. Can you imagine what kind of dust storm they would have created? All the vehicles and helo's were painted a sand/tan. Makes one wonder.... what the heck those guys were up to!??