“I think they may have come from the same era, or system,” answered Jean. “It is in the limestone, I know, that the remains of mammals were first discovered.”
“Sandstone and shales,” Ruth said. “It’s all the same age, but the systems are different.”
“How do you know so much about it?” asked Ted, suspiciously. “Have you been looking it up while we slept, grandma?”
“I love rocks,” Ruth replied, with her slow, whimsical smile, and little uplift of her chin as she looked through her glasses at them. “I think they are the first primer of the world, where we get our A B C’s, don’t you, Miss Jean?”
“Oh, won’t the Doctor have a good time prowling around with Ruth,” Polly exclaimed. She clambered ahead of the rest, trying to keep up with Peggie, who went like a mountain goat from rock to rock, and up the steep inclines.
“How about trout?” called Sue. “Who said trout?”
“We’ll have time on our way back. How far is it, Peg?” called Miss Murray.
“Most there now,” came back Peggie’s voice far up among the rocks.
At last they caught up with her. It was directly under a great, beetle-browed crag, with mats of ferns overhanging from its edges like lace. There had been a wash-out, or some sort of natural force that had carried away with it a mass of the hillside at this point. The great roots were exposed, with earth clinging to them still, and vegetation trying to get a foothold. But Peggie did not stop. As soon as she caught sight of the girls coming through the undergrowth towards her, she turned and dipped into the cavernous mouth of the great earth opening.
“This is what I meant looked like big bone spools,” she told them. “Don and I found them.”