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Show 278 DENUDATION '1.'0 LAND CrraP. VI. bleached petioles, in comparison with those of other plants of the same kind, where there had been no such accumulation. The earth thus accumulated had no doubt been secured (as I have everywhere seen) by the sn1al1er roots of the plants. After describing this and other analogous cases, Dr. King concludes: "I can have no doubt that worms "help greatly in the process of denudation." Ledges of earth on steep hill-sides.-Little horizontal ledges, one above another, have been observed on steep grassy slopes in many parts of the world. Their formation has been attributed to animals travelling repeatedly along the slope in the same horizontal lines while grazing, and that they do thus move and use the ledges is certain; but Professor Henslo'v (a most careful observer) told Sir J. Hooker that he was convinced that this was not the sole cause of their formation. Sir J. !looker saw such ledges on the Himalayan and Atlas ranges, where there were no domesticated animals and not 1nany wild ones ; but these latter would, it is probable, use the ledges at night while grazing like our domesticated animals. A friend observed for me the ledges CIIAP. VI. LEDGES ON HILL-SIDES. 279 on the Alps of Switzerland, and states that they ran at 3 or 4 ft. one above the other, and were about a foot in breadth. They had been deeply pitted by the feet of grazing cows. Si1nilar le~ges were observed by the same friend on our Chalk downs, and on an old talus of chalk-fragments (thrown out of a quarry) which had become clothed with turf. My son Francis examined a Chalk escarpment near Lewes; and here on a part which was very steep, sloping at 40° with the horizon, about 30 flat ledges extended horizontally for more than 100 yards, at an average distance of about 20 inches, one beneath the other. They were fron1 9 to 10 inches in breadth. When viewed from a distance they presented a striking appearance, owing to their parallelism; but when examined closely, they were seen to be somewhat sinuous, and one often ran into another, giving the appearance of the lodge having forked into two. They are formed of light-coloured earth, which on the outside, where thicke t, was in one case f) inches, and in another case between 6 and 7 inches in thickness. Above the ledges, the thickness of the earth over the chalk was in |