Just at the spot where we struck the groove, it divided into two, for this reason.
In its centre the floor of iron, or whatever it may have been, rose, the fraction of an inch at first, but afterwards more sharply, and this at a spot where the groove had a somewhat steep downward dip which appeared to extend onwards I know not how far.
Following along this central rise for a great way, nearly a mile, I should think, we observed that it became ever more pronounced, till at length it ended in a razor-edge cliff which stretched up higher than we could see, even by the light of the electrical discharges.

Standing against the edge of this cliff, we perceived that at a distance from it there were now two grooves of about equal width.

One of these ran away into the darkness on our right as we faced the sharp edge, and at an ever-widening angle, while the other, at a similar angle, ran into the darkness to the left of the knife of cliff.

That was all.
No, there were two more notable things.

Neither of the grooves now lay within hundreds of yards of the cliff, perhaps a quarter of a mile, for be it remembered we had followed the rising rock between them.