494 Dr. Nicholson — On Plants in the Skiddaw Slates. 



Skelwith Force, and receiving the drainage of Loughrigg Tarn, 

 joins the Eothay and falls into Windermere, which also receives 

 Blelham Tarn, Esthwaite Water, Out-Dubs Tarn, and other small 

 lakes ; the Lake Windermere itself flows down the Leven, a con- 

 siderable river, of which the Eiver Crake, which drains Coniston 

 Water, is a tributary. The two rivers unite at Greenodd and flow 

 into Morecambe Bay, between Ulverstone and Cartmell. The Leven, 

 at its mouth, therefore, contains the drainage of at least twenty 

 lakes, of which five are of considerable size, and I think few can 

 doubt that this river has been partly instrumental in the formation 

 of "Morecambe Sands." And, secondly, again considering the 

 immense depth of some of the lakes, the deep chasms in which they 

 lie, it is impossible to say that there are not immense quantities of 

 detritus concealed beneath their placid waters. At the time of my 

 visit last month, from the dryness of the season, the heads of many 

 of the lakes were dry, and I was, therefore, able to examine several 

 of them, and I found the bottom invariably to consist of fine alluvial 

 sand, capped by a thin coating of peat or vegetable growth; a 

 section through one of these deposits would probably exhibit a 

 succession of thick bands of alluvium, and thin seams of peat, the 

 former thrown down in winter, the latter formed in summer; in 

 this way several tracts have been reclaimed at the heads of several 

 of the lakes. 



I have been induced to publish the above hasty notes, because, 

 with the exception of Mr. Mackintosh's paper, to which I have so 

 often referred, little has been printed on the Surface-geology of the 

 district. I have abstained from giving any sections of details, 

 leaving them to the more able hands of those officers of the Geo- 

 logical Survey, who are now engaged in the survey of that region. 



On my way south, I called on Mr. Bolton, of Ulverstone, the 

 author of a most interesting work on the geology of Furness (the 

 result of more than seventy years' labour), who showed me blocks of 

 limestone bored with holes from the neighbouring mountains, and 

 other blocks from the sea-beach of Walney Island, also composed of 

 Carboniferous limestone, with similar holes, in each of which may be 

 seen the two perfect shell-valves of a Pholas. But none of the 

 holes were quite so large as those described to me by Mr. Mackintosh, 

 as occurring in the block he sent up to the Geological Society. 



IV. — On the Oocukrence of Plants in the Skiddaw Sxates. 



By Henrt Alleyne Nicholson, M.D., D.Sc, M.A., F.G.S., Lecturer on Natural 

 History in the Extra- Academical School of Edinburgh. 



(PLATE Xyill.) 



THE occurrence of plant-remains in the Silurian and Cambrian 

 rocks is a subject of great interest, but one which has not 

 hitherto been sufficiently investigated. Many supposed plants have 

 been described by Emmons, Hall, Billings, and Dawson, from the 

 older Palaeozoic rocks of North America, and little doubt can be 



