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Show TRANSPORTATION OP DEBRIS. 215 deposited, as compared with the distances traveled by finer detritus. Instances where stones weighing from two to five pounds have traveled 50 miles are common. Where ice is the vehicle, the distance may be almost indefinitely great. It would seem to require extraordinary circumstances to justify the belief that a conglomerate could be formed as far as 50 miles from the sources of its fragments, and it is probable that most of the stratified beds are formed in the very neighborhood of those sources, though beds of small gravel, graduating into coarse and then into fine sandstone, may extend away much farther. Transportation.â€"Transportation by ice, whether floating, or moving upon the land, forms a subject by itself, and has no analogy to the agency of water in moving debris. It will therefore be passed over, since it takes no part in the operations which are the object of this discussion. The movements ol the coarse materials which build up conglomerates differ from those of the finer sediments, though they have something in common. The greater portion of the fine silt, much of the fine sand, and the whole of the chemical and organic precipitates are carried by moving waters in suspension, and are thrown down when the waters come to rest. The coarser materials are impelled along the bottoms of rivers and the shelving floors of the ocean and lakes near the beaches. Here the want of habitual observation and common experience is apt to mislead us and render difficult the obtaining a just apprehension of the nature and magnitude of this impulsion. Any day we may see the rivers turbid with earthy matter, and it is an easy step from this observation to the great generalization that the land is wasting away and heavy strata accumulating beneath the ocean. But it is not so easy to see what goes on beneath the water. The times when the processions of stones are on the move are times of high water, and flooding rains, when geologists are as prone as other people to seek the kindly welcome of roofs and closed doors; times when the deep and murky waters prevent us from seeing and the roar of the torrent from hearing the movement, even if we ventured out to watch it. Thus, the process is not a matter of common and direct experience; nay, experience might seem at first to lead us to a contrary conclusion. When a stream is low and clear |