Decomposed granite. Eroded from Pikes Peak. What is this about "this years gravel on the county road"? We are lucky if we see new gravel every 20 years.
Years ago in coal mining country, we had what was referred to as Red Dog.It was the burned up slate piles and that had some coal mixed in with it .These big piles would catch fire and smoulder for years.Once they burned themselves out, the remains made good road gravel if you could call it that.
