The gooey appearance of a rock wall in Manu Nui cave was formed when the lava chemistry started to change and the iron contained in the lava oxidized into various minerals. Manu Nui is ...

The iron isn't pure—scientists believe it ... Many people think of this as lava, but it's actually rock. The rock is so hot, however, that it flows under pressure, like road tar.

Passing by a series of subterranean geological features named cave chocolate, cave bacon and cave popcorn, I start to wonder ...