Animal and even plant horror are familiar categories: you can find entries for horror films featuring mammals, reptiles, amphibians, insects, birds, and plants, for instance, on Wikipedia (check out the List of Natural Horror Films). So far, however, you’ll be hard-pressed to find anything about geological horror. So where are the horror films about rocks and minerals? (That’s not a rhetorical question: if you know of any, please let me know!)
There are, of course, a multitude of films about natural disasters (tsunamis, volcanoes, earthquakes, avalanches etc.), but these films tend not to be horror films (they’re routinely classified as action)—and natural disasters are typically not exploited in the horror genre—except sometimes as plot devices to trap characters in places where they have to face other monsters.