I think you need to consider that all mtn ranges in the US are basically still moving, growing, rising, slipping tectonically, etc. Given this premise, then yes, the ADX are the oldest range. The rock is the oldest, and they were formed the longest time ago into something resembling the current day range. The fact that something happened a few million years ago to modify the range is irrelevent to the question at hand. Most Geo courses generally espouse this view, as noted by Dr. Fred Lobdell above, Perfesser of Geology. To answer the 1st question, the ADX are the oldest mtn range in the US.