Page:Transactions of the Geological Society, 1st series, vol. 4.djvu/368

 impression on the opposed angles at the point of flexure must be different. Where the salient angle occurs it is plain that it will be more subject to the effect of the water on the side which opposes the current, than on that which declines from it. The same effect will take place at the re-entering angle, but the corresponding sides about the angle will be affected in the reverse order. If therefore the current consists of a mixed mass of earth and water, the principal deposit will be found to leeward of the salient angle, while the windward side (if we may use this metaphorical term) will, remain clean. A similar effect, but in a reverse direction, will take place on the re-entering angle, which however will be more marked by the want of deposit on the side opposed to the stream, than by any accumulation on the other side that includes the angle. But if the current should have consisted of water alone, acting on a previously deposited alluvium, the effects will be of a contrary nature, since the greatest impression will, on both angles, be produced on the side that opposes the stream. Similar effects, but in a more marked degree, must take place wherever such sinuosities and furrows occur as to form a shelter to the sides from the direct action of the current. Yet we have seen that the lines are traced at the numerous indentations and flexures which Glen Roy exhibits, with a total disregard of this circumstance, and with a degree of equality that would have been impossible on such a supposition.

Another argument of a nature somewhat similar to this may be found in the form of the upper part of Glen Roy, already fully described, and to render it the more tangible, it is illustrated by a plan and section. Here the form of the ground produces a complete shelter from the action of any current, which, like that supposed, must have been directed