In removing the sweaters, Polly accidentally pulled out a heavy coil of rope, but hung it back on one of the knobs of Choko's harness instead of buckling it inside the pocket. Well she did, too.
"Come on, girls, I want to see what that blue line is over on the ice-field," said Polly, starting up the Slide.
The horses were sharp-shod and sure-footed, so the girls rode as safely as if on the mossy trail, but they had not gone far before Polly began murmuring to herself.
"What's the matter?" wondered Anne, aloud.
"That blue line looks to me like a crevice in the ice."
"What of that?" asked Barbara, stupidly.
"That shows something queer! This slide seldom cracks into fissures, but when it does it means trouble. If that crevice goes down very deep it shows unusual warmth underneath. And that may move this upper section of ice-field any time, thus creating an awful land-slide, don't you see?"
"Oh, mercy! Let's hurry back!" cried Barbara, wheeling her horse immediately.
"It isn't likely to occur as quickly as that, Bob," said Anne, soothingly. Then turning to Polly, said: "But this slide is said to be stationary."
"It has moved, but so seldom that folks never fear it. I know something about land-slides after living in Pebbly Pit for fourteen years, and even a little slide at the lava cliffs causes an awful destruction, so I can picture what this gigantic slide would do if it ever got started down!"