. Elements of geology, or, The ancient changes of the earth and its inhabitants as illustrated by geological monuments. Geology. 140 MORAINES AND ERRATIC BLOCKS. [Ch. XL half a mile in a single year. We also learn from M. Yenetz, that whereas, between the eleventh and fifteenth centuries, all the Alpine glaciers were less advanced than now, they began in the seventeenth Fiar. Limestone polished, furrowed, and scratched by the glacier of Kosenlaui, in Switzerland. (Agassiz.) a a. White streaks or scratches, caused by small grains of flint frozen into the ice. b &. Furrows. and eightee
. Elements of geology, or, The ancient changes of the earth and its inhabitants as illustrated by geological monuments. Geology. 140 MORAINES AND ERRATIC BLOCKS. [Ch. XL half a mile in a single year. We also learn from M. Yenetz, that whereas, between the eleventh and fifteenth centuries, all the Alpine glaciers were less advanced than now, they began in the seventeenth Fiar. Limestone polished, furrowed, and scratched by the glacier of Kosenlaui, in Switzerland. (Agassiz.) a a. White streaks or scratches, caused by small grains of flint frozen into the ice. b &. Furrows. and eighteenth centuries to push forward, so as to cover roads formerly open, and to overwhelm forests of ancient growth., These oscillations enable the geologist to note the marks which a glacier leaves behind it as it retrogrades ; and among these the most prominent is the terminal moraine, which is a confused heap of un- stratified rubbish, like the till before described; all the mud, sand, and pieces of rock, with which the glacier was loaded, having been slowly deposited in the same spot where no running water interfered to sort them, by carrying the smaller and lighter particles and stones farther than the bigger and heavier ones. These terminal moraines often cross the valley in the form of transverse mounds, more or less divided into separate masses or hillocks by the action of the torrent which flows out from the end of the glacier. Such transverse barriers were formerly pointed out by Saussure, below the glacier of the Ehone, as proving how far it had once transgressed its present boundaries. On these moraines we see many large angular fragments, which, having been carried along on the surface of the ice, have not had their edges worn off by friction; there are also many boulders, of various sizes, which have been rounded; some, as before stated, by the power of water beneath the glacier, others by the mechanical force of the ice which has pushed them against each other, or agai
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Keywords: ., bookcentury1800, bookdecade1860, booksubjectgeology, bookyear1868
