Last weekend, Andy and I went to visit the Ape Caves. So the caves formed a about two thousand years ago due to a basaltic flow. Basaltic flows are very unusual and normally found only in Hawaii. The caves are called Ape Caves after the sponsor of the Boy Scout troop that first explored the caves. The caves are very dark and very cool.
We went on the more difficult route with little knowledge of how difficult it would be. Here’s the description from the site:
The 1½-mile (2100m), upper portion of the cave takes about 2½ hours to complete, returning on a surface trail. Cavers must climb over approximately 27 boulder piles and scale an 8-foot (2.5m) high lava fall.
The boulder piles, called breakdown, formed after the eruption subsided and the fluid lava drained from the tube. As the lava tube cooled, it began to shrink and crack. These cracks weakened the ceiling and walls causing parts of them to collapse. The entrances to Ape Cave formed in this way.