Chapter 12 is another one of those chapters where we don't have plot, just a lot of natural description.
We're taken on a trip back way before human beings scampered across the earth, before the earth was broken up into continents. The landmass on which India was located preceded the rise of the Himalayas and the separation of Asia from Africa.
The Marabar Caves are extensions of this ancient landmass. They contain a series of caves that are baffling. The interior of each cave has a highly reflective surface. Visitors can strike a match and the flames are reflected all around them. There are rumors that there are caves even farther in which have no access to the outside world. The strangest cave is the one in a boulder that is perched on the summit of the highest hill. It's called the Kawa Dol.