yes it is a giant caldera above a super volcano.
OT I think it's funny that whenever this has been brought up and someone hears national land, they instantly think the government is going to sell off our national parks. I have a really hard time believe someone is touching the national parks. our national land is mostly NOT the national parks.
I've personally not looked into this enough to see what they are selling for what purpose and to whom. So this is the most I can contribute. I should probably look into it more...