At length Modoc halted on the brushy tree–bordered rim of the largest depression Ben had seen. It was over an acre in extent, precipitous on three sides, and shelving very roughly on the fourth side. Deep and flat–floored, it formed a remarkable natural corral. Ben’s sharp eye was quick to note where a trail had been worn, narrow and sharp and steep at the rim, and gradually growing broader and easier of descent until it resembled a road. It led into a gigantic cavern.

“Geemanee!” ejaculated Nevada. “Made to order!”

“Modoc, the water’s down in that cave,” asserted Ben, eagerly, pointing.

“Big hole full water. No bottom. Ice all over,” replied the Indian.

“By golly! Nevada, we’re rich. Let’s go round to the head of that trail and have a look.”

Ben had heard from the Indian how the Modocs used to lie in ambush around this cave, watch at night for the wild horses to go down to drink, then run and block the narrow place where the trail led over the rim. How absurdly simple the trap! The moment Ben laid eyes upon the head of the trail he felt almost shame to be guilty of catching wild horses so easily. There were, however, two great difficulties. One was that only in rarely occurring, extremely dry seasons were the wild horses driven to this extremity. And secondly after they were trapped in the cave, to get them out safely was a hazardous and strenuous undertaking. That did not in the least daunt Ben; he had a way with horses, and as for Nevada, the cowboy was incomparable with a lasso.

Modoc shuffled away to begin chopping down saplings. When Ben had gazed his fill at that fascinating trap he drew Nevada away with him to help the Indian. They built a gate, so heavy that they had difficulty in carrying it to the objective point, where they partially hid it under brush. Two great boulders of lava, one on each side of the trail, attested to their use as anchors for trap–gates in the past.

“Doggone!” ejaculated Nevada, after heaving one of the boulders into better place. “Is this all the work we have to do? Shame to take the money!”

“The worst is to come,” replied Ben, in grim satisfaction.

“You mean gettin’ the hosses up out of there an’ movin’ them, after we do ketch them?” queried Nevada.

“I sure do. It’ll be the toughest job we ever tackled.”

Whereupon the cowboy subsided, and lost his enthusiasm in thoughtfulness. On the return to camp Modoc explained one of the methods adopted by the Indians for capturing the horses after they had been trapped. It was to let one or two out of the gate at a time and rope them. But Ben could not accept this plan as practical for him. The Indians wanted only a few horses, while he wanted many. It would take time to capture them.

“Well, let’s wait till we see how many we trap and how good they are,” decided Ben, finally.