"What causes it?"
"Carbonate of lime, or chalk, which is caused by lime water coming from above and trickling down through to openings or crevices, and leaving the deposits there. It is not an uncommon thing in caves, and I foreshadowed it in the cave when I stated that the rocks were of limestone formation. You will remember we made lime from this kind of rock."
A loud splash and a groan-like noise put further conversation at an end. "What was that?" asked George, as he retreated. In doing so he tripped, and, in falling, the light he carried was extinguished as it flew from his hand.
Clearly there was water ahead. "Let us go forward, a little closer," said the Professor. "You might get your guns ready, in case of necessity."
Within thirty feet of them was the edge of water, and the light threw a beam beyond for a hundred feet or more.
"It seems as though we have reached the end of our explorations here." As they looked, the water was agitated, and it was plain that some aquatic animal was within the cave.
To return was the only thing to do, and as they went back the sides of the cavern were examined, and the Professor took a number of samples, as he said: "Don't lose the candle until we get where we can see daylight. Although we are not more than two hundred feet from the mouth of the cave, the remarkable bend or jog near the mouth of the cave makes it as dark as though we were in a thousand feet."
"What sort of animal do you suppose that was?"
"Possibly a sea lion, or a seal."
After the open air was reached the Professor said: "I do not see how this cave would account for the phenomena that George saw the other day."