THE ORIGIN OF LAKES. 227 



to which loosening of blocks had taken place." The forma- 

 tion of these little rock-basins, then, appears to have been 

 primarily due to unequal weathering, the sole work of the 

 glacier having been to remove the weathered blocks. 



During the present year I had an opportunity of seeing 

 some very tiny pools produced by unequal weathering in a 

 way which, if conducted on a larger scale, might give rise 

 to small lakelets. In the Langstrath Valley of the English 

 Lake District is an alluvial plain, terminated by a gorge 

 which I have elsewhere described as apparently due to the 

 stream issuing from a vanished lake. A wall runs at right 

 angles to the gorge on the east side. On the south side of 

 the wall some exquisite potholes are seen at a considerable 

 distance above the stream, though these are not the rock- 

 basins to which I wish to refer. On the north side of the 

 wall are shallow depressions in the rock, in various stages of 

 formation. One, eighteen inches long and three inches 

 deep, was filled with water, but it had a deposit of peaty 

 silt on its floor. Another " basin " about three feet long 

 was filled with heather, grass and moss, and a similar patch 

 of moss, grass and heather occupied a space about twelve 

 feet long, surrounded on all sides by naked rock. It is well 

 known that the organic acids supplied by vegetation assist 

 the weathering of rock, and that the water is also held 

 against the rock for a much longer period where the rock is 

 covered by vegetation than where bare, so that vegetation 

 tends to cause the rock to be etched away beneath it, and 

 in this Langstrath rock one saw how small lakelets might 

 be produced, and indeed were in actual process of forma- 

 tion on flattish surfaces of rock owing to this cause. It is 

 doubtful how large a basin could be produced in this way, 

 but I see no reason why considerable lakelets should not 

 arise in this manner after the death of the vegetation which 

 had covered the rock. It is well known that peat-mosses 

 are frequently due to the former existence of lakes, but it is 

 not so generally recognised that, conversely, lakelets may 

 be due to the former existence of peat-mosses. 



I have been induced to write this paper on lakes because 

 I believe that there is still much valuable work to be accom- 

 plished even in our country with reference to the origin of 



