Page:Transactions of the Geological Society, 1st series, vol. 4.djvu/380

 skirted by a gravelly shore, forming an inclined plane and constituting a zone at the level of the water; of greater or less breadth according to the declivity of the hill, the quantity of alluvial matter present, and the nature of other circumstances which occasionally modify the action of these causes. Thus on entering a few feet within such a lake on a shore of moderate inclination, we plunge suddenly down, and in such a case it will be found that the soundings which succeed to the narrow zone above described, generate a section of which the line indicating the declivity is continuous with that which lies similarly above the water. Wherever rocks protrude on the face of a hill in such circumstances, the shore above described is either altogether wanting or imperfectly marked; according to the particular inclination of these rocky faces, or according to other circumstances on which it is unnecessary to dwell minutely. Where the declivity is greatest, the shore is not only narrowest, but its inclination is the greatest; and vice versa, it is most level and of largest dimensions where that is least. The reader who will recall to mind the particular description of Glen Roy, will recognize all these features in the present state of the lines; and it is scarcely to be doubted, that if the sudden drainage of such a lake as I have here described could be effected, its sides would present the appearances which occur in that valley, as far at least as all the requisite conditions were present. The conditions which have led to the uniform appearance and prolonged extent of the lines of Glen Roy, may be found in the general equality of the slope of the hills, their uniform and rarely interrupted faces, and the generally equal thickness and lubricity of the alluvial coat which covers them. Indeed whenever these conditions are absent we see those anomalies which on general principles we might be led to expect. It is true that I have in the description pointed out other anomalies which do not