“You’re sitting right beside it now.”
Weston gazed at him in blank astonishment, and then a light broke in on him.
“The willows?” he said. “The water in that creek would no doubt spread underground, and this is evidently an unusually dry season. Still, Grenfell spoke of a mile or two of water. Where has it gone?”
“That,” explained Devine, “seems the simplest thing of all. Anyway, I’ll give you my theory. When I crawled along the edge of the willows this afternoon, I found the outlet of an old creek and a beaver-dam. Now we’re assuming that the creek I’ve mentioned once ran into the lake just here, that is, before a snowslide filled up the ravine with debris and diverted the creek into the other gully, the mouth of which is—below—the beaver-dam.”
“You have explained how the water got here, not how it got away,” said Weston, impatiently.
“No,” replied Devine. “I haven’t explained either of them yet; but we’ll get on a little. Once, and I don’t think it was very long ago, there was a little water with a creek flowing out of it in this hollow. A colony of beavers came along and put up their dam across that creek, and that backed the water up a foot or two. If you’d skirted this hollow you’d have seen that it’s tolerably level, and a foot rise would spread the water quite a way. I want to say that it was probably a swamp with only grass on it when the creek ran through it. Well, the beavers liked the place, and piled up their dam, while the water went farther and farther back across the swamp. Finally, the beavers either died off or something drove them out. It was probably after that that the dam broke down and the water ran off. Then the snowslide cut off the creek, and as the hollow dried out the willows spread across it.”
Weston could find no fault with this train of reasoning, which made comparatively plain Grenfell’s long and unsuccessful search.
“Yes,” he admitted, “it’s logical, and I think it’s correct. I believe, from what Grenfell once said, that he crossed the range to the east of us, not far away, some years ago with another man, and he must have noticed this valley. Further, I now feel reasonably sure that he and I once stood on the shoulder of the big peak in the southwest and looked right up the hollow.” He smiled rather grimly. “We naturally saw nothing. We were looking for a lake that had dried out.”
He lay still for a minute or two, and then broached the subject that both had held in abeyance.
“Well,” he said, “what’s to be done?”