I worked for the NPS for a 10 week stint in the Mojave Desert Preserve and can offer some insights, perhaps. Let there be no doubt in your head, that the juggernaught that is the NPS is a monster. It is a buearucarcy that defeats all attempts to manage it.
It allows incompetents and fools to hide within it's folds and hang out till retirement.
That is the truth. But..there are other truths as well. The NPS does great work. And pretty much any of the staff I came into contact with are devoted, hard working souls that have found a life long 'home'. The NPS tolerates those that have difficulty working in 'normal' environments. From the managers right on down to the people on the ground doing back-coutry work, there is a pride in the wearing of the 'badge'.
If a person is a bit of a loner and has a bent for the odd-balls of the world..they'd do well. If a person can tolerate the black and white of beauracracy and muddle thru the maze of apparent nonesense and fiefdom building and just find a niche, hunker down and get known.
One of the problems is that much of the NPS work is seasonal, so..the people that are doing the ground work get released at seasons end. There is lots of secret bum patting and back-stabbing..trying to find a new gig or next years.
If a person can identify a job..in your case a geologist, then dig around and determine which NPS locations have need of one...then be in touch with the manager of that locale. Are you looking for paid work or a Volunteer position? As a Volunteer you'd be able to look at many various sites. And you learn the ins and outs of the organization. I'd sugggest that perhaps you look at Volunteering first. Get in the door and learn the ways of the NPS. That way, too..if you can't quite get comfy with the whole thing, at the end of the your term, you can just walk away. No harm, no foul. But..being a Volunteer doesn't allow for easing of the 'rules'. OMG, no. So..it is still a monster, but one you can laugh at.
Gary Haupt