Docs golden eyes ranged the crater edge as great a distance as possible. Due to the gloominess of the light which penetrated the clouds above the pit, the opposite wall of the crater was lost to sight. Long plumes of steam arising from what were obviously streams of boiling-hot water, helped hinder vision.
The day was really a hot, wet, ghostly gray twilight.
"I do believe Ive seen moonlight brighter than this!" Long Tom said.
But they could get a fair idea of their surroundings. The utter denseness of the jungle was a thing to cause awe.
As they stood on the knoll, another sudden rainstorm came. Steam rolled from the hot mud lake like fluffy cotton. The violent downpour seemed to occur several times each day.
"The tremendous rainfall is caused by the moist hot air lifting to the cold air at the top of the crater, where it condenses and falls back as rain," Doc Savage explained. "The great rainfall also explains the plant growth being so rank it is nearly a solid mass."
He glanced about appraisingly.
"This vegetation is only slightly less dense than that which flourished during what scientists call the coal age."
"You mean it was jungle like this that made coal beds?" Monk grunted.
"Exactly. Let a landslide cover some of this jungle, or let water and mud cover it, and in the course of a few ages, we would have an excellent chance of a coal vein. Partial decomposition without access to air would do the work."
FURTHER appraisal of their amazing domicile led Doc to level a mighty bronze arm.
"There, brothers, is the explanation of these prehistoric life forms being forced to remain here through the ages!"
Johnny, the geologist, quickly comprehended what Doc meant.
"At one time a path gave access to the crater," he declared. "Some natural upheaval, probably an earthquake shock, destroyed the means of getting in and out. And the dinosaurs were forced to stay."
"Through the aeons of time that they have remained here, the outer sides of this cone weathered down. The land sank. Oceans rushed in. And this crater became Thunder Island, supposedly an active volcanic cone projecting from a seldom-visited section of the southern seas."
Monk scratched his bullet of a head. "But, Doc, how do you account for these critters not changin through the ages, like they did in the outer world?"
"Evolution," Doc smiled.
"But evolution is a changing "
"Not necessarily," Doc corrected. "Evolution is a change in animals and plants and so on, as I comprehend it. But those changes are caused by slowly altering surroundings. For example, if an animal lives in a warm country, its fur will be light, or it may have no fur at all. But if the country turns cold, the animal must grow a heavy coat, or perish. The acquiring of that fur coat is evolution.
"Conditions here in this crater have remained exactly as they were ages ago. The air is warm. There is a great deal of rain. The luxuriant plant growth makes food plentiful. Probably the seasons down here are alike the year around.
"So the prehistoric animals trapped here experienced no necessity for changing themselves to fit altered conditions, because conditions did not alter."
"That sounds reasonable," Monk admitted.
After this, silence fell. It was a somber quiet. They were thinking of Renny. They believed him dead, on the evidence of what they had seen his hat and the gore surrounding it.
"Wed better be moving," Doc said at last. "First, we will visit the neighborhood of the hot mud lake, on the chance some supplies might have spilled out of our plane. In case you havent noticed it, were practically out of ammunition."
The others hastily examined their guns. They found only a few cartridges in each weapon. Monk, naturally the most reckless, had but four cartridges left.
"Throw the lever which changes your guns to single-shot operation," Doc directed. "Weve got to count every bullet. Although the weapons are virtually useless against these prehistoric monsters, they will be effective upon Kar."
"Kar!" Ham clipped. "I had nearly forgotten that devil! Have you noted any signs of him, Doc?"
"Not yet. But we are not giving up our pursuit. Not even these big dinosaurs can keep us from Kar."
THEY visited the hot mud lake. So terrific was the heat of the lavalike stuff that they could not approach within yards. Too, they dreaded a sudden eruption, such as had been caused by the plane plunging into the lake.
Such geyser displays apparently came often. Great splatters of mud, now cooled, decorated the steep slope for some distance below the hot lake.
"Imagine one of them droppin on the back of your neck!" Monk mumbled.
"Better still, imagine what would happen to the crater floor if this broke!" Ham pointed at the lavalike dike retaining wall which confined the horseshoe-shaped body of super-heated, jellylike mud well upon the crater side.
"It would be too bad on a pig, if he happened to be down on the crater bottom, huh?" Monk suggested. Then he watched Hams features assume the inevitable flush of ire.
They found no speck of equipment from the plane. The craft was hopelessly gone.
To show there was no chance of salvaging it, Doc cast a small chunk of wood out on the crusted lake surface.
So hot was the crust that the wood smoldered and quickly burst into flame!
"Golly!" muttered Monk. "Lets get out of here before that thing takes a notion to cut up!"
"We shall skirt the crater," Doc decided. "You notice the larger vegetation grows near the edges. In the center is a series of small streams. These bodies of water run sluggishly, and are hardly more than elongated bog holes."
"How about lighting a fire and getting some breakfast?" suggested the taxidermist, Oliver Wording Bittman.
Bittman had indeed regained much of his nerve. But it was with a patent effort that he was striving to maintain the standard of calmness before peril set by Doc and his men.
"No fire," Doc replied. "It might show Kar our whereabouts, if he is in the crater. Anyway, we have nothing to cook."
"The breakfast part of his idea still sounds good to me," spoke up Long Tom. "What do we eat, Doc?"
"Ill try to find something," Doc smiled.
They betook themselves from the vicinity of the mud lake.
"Quite a climb!" Ham puffed as they descended the steep slope.
Ham, amazingly enough, had retained his sword cane through all the excitement of the parachute leap and the horror of the ensuing night. He was seldom without that secret blade. But, although it was mightily effective upon human opponents, it was virtually useless against the giant dinosaurs. The tempered blade would snap before it could be forced through one of the thick, wood-hard hides.
However, Ham very soon got a chance to use his sword cane.
An animal about the size of a large calf suddenly bounded up before them. It had four spongy looking antlers, two in the usual spot atop the head, the other pair down below the eyes. It had a cloven hoof and looked edible.
With a swift spring that would have been a credit to even Docs brawny form, Ham ran the strange animal through with his sword cane.
"We eat!" he grinned.
"I HAVE an idea how we can build a fire without the smoke being noticed," Doc offered. He had suddenly discovered he was hungry. "Well kindle a blaze near one of these streams of boiling water from which steam arises."
"Talk about necessity being the mother of ideas!" Monk grinned.
They kindled a fire, although experiencing difficulty with wet wood. Too, another sudden deluge of rain nearly put out the flames. But at length they had their breakfast cooking.
"What are we eatin?" inquired Monk.
"A primitive type of deer," decided Johnny, the geologist.
By dipping a corner of his handkerchief into the boiling stream beside which they had built their fire, then permitting the wet cloth to cool and tasting it, Doc ascertained the water was drinkable, although it had a saline quality.