Page:Popular Science Monthly Volume 18.djvu/584

568 the most recent of all the gravels of the Delaware Valley. 2. That the palæoliths found in it really belong to and are a part of the gravel, and that they indicate the existence of man in a rude state at a time when the flooded river flowed on top of this gravel. 3. That the data do not necessarily prove, geologically considered, an extreme antiquity of man in Eastern America."

Prehistoric Mining in North Carolina.—Mining for mica has become a profitable pursuit in North Carolina. It is a curious fact that the best mines are located upon sites which afford evidence of having been worked in prehistoric times, and are called there "old diggings." Most of the old works probably belonged to the mound-builders, but a tradition coming down from the Indians ascribes some of them to white men. The tradition has recently been confirmed by the discovery of old implements of iron in a prehistoric shaft in Macon County, which are fully described and figured by Mr. F. W. Simonds, in the "American Naturalist." The implements were found in the rubbish which had accumulated within the shaft, between thirty-five and fifty feet below the surface, and consist of an axe of a pattern now rarely met with, light in weight, and having on the blade a brand which has been nearly effaced by erosion; two articles which were evidently gudgeons of a windlass, with heads pronged for the insertion of levers, pointed at the ends, so that they could be driven into a wooden roller, and having the lower part of the shank squared to prevent their turning in the wood, and the upper part round so as to serve as an axle for the roller; and a wedge with battered head. All were of wrought iron, and had probably been worn out and thrown away. Mr. Simonds suggests that they are the relics of a party of Spaniards who left one of the ancient colonies or expeditions on a "prospecting tour" and tried the mines. Less palpable evidences of more skillful mining than that of any aborigines have been found in other shafts.

The Great Glacier of the Yellowstone.—Professor Archibald Geikie, Director of the Geological Survey of Scotland, gives in the "American Naturalist" an interesting notice, based on his personal observations, of the ancient glaciers of the Rocky Mountains. He refers to the absence of signs of glacial action in the region between the Missouri Valley and the Sierra Nevada, which has been mentioned by American geologists, and regards it as the result chiefly of meteorological conditions. Then, having spoken well of the accounts given of the glaciers of the mountains by our geologists, he records his own observations of them. Entering the Yellowstone Valley from Fort Ellis, a little above the first cañon, he observed a prominent rock like a cottage, and weighing more than a hundred and fifty tons, lying, like other smaller erratics around it, on crescent-shaped mounds—moraine-heaps—in the midst of the alluvial plain. The broad valley was full of moraine stuff. Here, he observes, was a great glacier moving northward, "while in British Columbia, on a parallel only about two hundred and fifty miles farther north, there was a massive ice-sheet moving southward. It will be a point of no little interest to trace these two converging ice-streams toward each other." In ascending the Yellowstone Valley toward the National Park, scattered moraine-mounds and abundant transported blocks continue to denote the course and size of the former glacier. The intense glaciation of the second cañon was a surprise. The rocky knobs at the lower entrance of the great ravine were as perfectly smooth, polished, and striated as the rocks at the margin of any Swiss or Norwegian glacier, and the steep sides of the canon had been ground and striated in the same way, to the height of certainly not less than eight hundred feet. Above the second canon the moraine-heaps become more abundant and tumultuous, here and there inclosing small lakes; and they were found also, with erratics, in the tributary valley's. The trail from the Mammoth Springs by Blacktail Deer Creek, over to the Yellowstone, leads across mounds of glacial débris among which huge bowlders of granite and granitoid gneiss are conspicuous. Some parts of the route present long, smooth slopes, dotted with bowlders precisely like some Scottish bowlder-clay moors. These signs of glaciation can be traced up to and