"That is true to-day, Jack," said his uncle; "but the time I am talking about was long, long ago, in what the men who study the earth's history call Jurassic time. No one knows how many years ago it was, but it is safe to say it was millions. In those times the salt ocean, or an arm of it, lay just east of the Rocky Mountains and the water in this bay where we are now was partly fresh and partly salt. Great forests grew here, and strange animals lived among them and fed along the shores of this bay. If we had time to get out and look for them, we could find beaches, where the sand was washed up by the waves, and shells, and the bones of these great animals. A big book could be written about these bad lands here, just as big books have been written about other bad lands."

"They're surely queer places," said Hugh. "I've seen it down in Kansas, and down on Henry's fork of Green River, and up in Oregon, where the ground was stuck full of bones and teeth. Some of the leg-bones was nigh as thick as my body, and some of the big heads had long teeth as long as my hand. They must have been big animals, and mighty dangerous too, I reckon."

"What makes the dirt all those different colours, Uncle Will," asked Jack; "In some places it's white, in others yellow or brown or black, and in some, bright red, like bricks."

"That red colour," said Mr. Sturgis, "is where the earth has been burnt. All through the soil here there are seams or veins of a crumbly brown substance, which is called lignite. It is a sort of coal about half made, and like coal it will burn. Sometimes a seam of this lignite catches fire from some cause or other, and may burn for years, baking the earth close to it. The heat turns it red, just as bricks which have been burned turn red."

By this time they were passing out of the bad lands and down into a flat through which flowed a broad river. There was no bridge over it, and Jack wondered how they were going to get across, but when they came to the water's edge the horses trotted in, were stopped to drink, and then walked on across, although the water came up to their bellies and washed and gurgled about the waggon, so that Jack began to think that perhaps they might be swept away. Pretty soon it grew more shallow, and then they came to the bank, and once more the waggon started off down the valley at a brisk rate. Soon they crossed a narrow little stream flowing between deep banks, climbed another hill, and then turning away from the river, went up a narrow valley, shut in on one side by a high wall of rock and on the other by a great mountain dotted with cedars. On this mountain Hugh said there were some mountain sheep, and he pointed out to Jack tracks in the road where some of these animals had crossed that morning. Further on, in a broad rolling valley, they saw some antelope, but by this time the cold wind had made Jack chilly and tired, and his uncle wrapped him up to the throat with blankets and robes, and propping him up between Hugh and himself, told him to go to sleep. Just as he was about to do this, something happened which woke him up very thoroughly.

CHAPTER IV
A GRIZZLY KILLED

Jack was just dropping off to sleep when he heard, very faintly, Hugh's voice, saying, "Got your gun handy, Mr. Sturgis, and some cartridges? Get it out quick then, there's a bear coming down from that bluff, and he's liable to cross the road a half mile beyond here; I'll run the horses and we may get there as soon as he does; he can't hear nor smell us in this wind." The last part of this sentence sounded very loud to Jack, for the word, bear, had thoroughly waked him up. When he opened his eyes, he seemed to have the seat all to himself. His Uncle Will's head was down between his knees, and he was feeling under the waggon-seat, while Hugh was half standing up and putting the whip on the horses. They did not need much urging to make them run, and in a minute the waggon was bounding along the road, jumping and swaying so that Jack held on to the back of the seat as hard as he could. His uncle had found his rifle, and was hurriedly fumbling with the straps of the case, and at the same time muttering questions to Hugh, asking where the bear was likely to cross.

In a moment more the rifle was pulled from its case, a cartridge slipped into the breech, and then the waggon topped a little rise of ground, and there before them, just crossing the road, was a big brown animal that looked something like a big dog without any tail. As they saw it, the horses tried to shy out to one side, but Hugh was ready for them and held them firmly. Mr. Sturgis rose to his feet and raised his gun to his shoulder, but Hugh said, "Hold on, hold on; wait till we get to where he crosses and then jump out. You will catch him as he rises the hill." Meantime the bear had crossed the road and disappeared in a ravine, and in a moment more Hugh drew up the horses, so that they almost reared, checked the waggon, Mr. Sturgis jumped out, and at that moment the bear was seen only fifty yards off, swiftly galloping up the hill. There was a shot, and then another, and the bear turned over and rolled down the hill out of sight. The horses danced, plunged, reared, and then ran some little distance before Hugh could stop them. But Jack looking back saw his uncle wave his hand and call out a cheery "All right!"

In a moment the horses stopped, and Jack jumped out and ran toward his uncle, not heeding Hugh's call to him to wait. Before he had reached Mr. Sturgis, however, the waggon had passed him, and when he got to the spot his uncle and Hugh were unhitching the horses, and in a moment had tied them to the hind wheels of the waggon.