Fenn made a dash for the shelter of a spruce tree, and watched the descending shower of mud and water. It was soon over, and he stepped out again, to view the curious volcano. He crossed the open space, free from snow, and a number of turtles scurried away at his advance.
“That’s how it is,” remarked the lad, “that the turtles are so numerous around here. It’s as warm as toast around that mud volcano, and they don’t have to hibernate. The ones we found near our camp must have wandered away in search of food, and were on their way back here. I’ve solved part of the mystery, anyhow. Now to examine this curious place.”
The boiling spring, or mud volcano, as such phenomenons are variously called, consisted, in the main, of a large pool of muddy colored water, lying at the foot of a hill. All around it were dead trees, and the smell of sulphur, though not so strong as at the first spring Fenn had visited, was plainly noticeable. The water had a dead, stagnant look, after the eruption, and Fenn was careful not to approach too close, for he could not tell when the spring would spout up again. He saw a number of turtles on logs and bits of wood that extended out into the pool, and others plunged from the bank into the water at his approach.
“They don’t seem to mind the sulphur and the mud,” said Fenn to himself. The lad had read in his school books of the mud volcanoes. They are of a type similar to the hot geysers of Yellowstone Park, though not so large or numerous. Though called boiling springs in some parts of the country they do not boil or bubble on the surface, as a rule, though there is a constant supply of warm water from some subterranean source, so, that, as in the case with the spring Fenn was viewing, the water ran over from the pool, and trickled off through the woods.
Mud volcanoes or boiling springs, while not common, are to be met with in New York and Pennsylvania. The writer recently visited a large one in New York State, near Lake Ontario. It was around Christmas, and a cold blustering day, yet the water from the spring was quite warm, and had melted the snow for quite a distance in all directions. The water was impregnated with sulphur and salt, and though there was not an eruption when the writer was present, there were marks on surrounding trees showing where mud had been hurled to a height of thirty or forty feet.
There are various theories to account for the action of the mud volcanoes. One is that steam is formed away below the surface, and, seeking an outlet, throws the mud and water with it. Another is that the force of water, flowing from some mountain lake, by an underground passage, spouts up through the boiling spring, being heated in some manner in its passage.
But Fenn did not trouble himself much about these theories as he looked at the curious spring. It was a gloomy, lonesome place, and the presence of so many turtles, some of them very large, added to the uncanny aspect.
“Well, there are turtles enough here to stock several collections,” murmured Fenn. “Lots of different kinds, too. I will take some home I guess. Now if I had that mysterious man’s address I’d send him word. This mud volcano will be a curious thing to show the other fellows. I wonder how warm the water is?”
He approached, to thrust his hand into the edge of the spring, when an ominous rumbling beneath his feet warned him. He jumped away just in time, and, as he ran for the shelter of the trees, there was another upheaval of mud, and he received a share of it. He remained in the shelter until the spring subsided, and then made his way back to camp.
His chums were there when he arrived, and something in their looks prompted Fenn to ask: