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GEOLOGY. 



NOTE ON A DEPOSIT OF LACUSTRINE MARL 

 IN WEST YORKSHIRE. 



Ev G. A. LEBOUR, M.A., F.G.S., 



P/'ofessor of Geology i7i, the Dicrhaiii College of Science, Newcastle-ou-Ty?ie. 



It may be interesting to many wandering geologists in West 

 Yorkshire to know that just now there is exposed, to view in the 

 Settle district a beautiful example of what was once an upland lake, 

 and is now a patch of lacustrine marl. 



Last Easter, whilst engaged on the annual geological week's 

 excursion of this College, we unexpectedly came upon a deposit of 

 white marl, which had evidently only quite recently been broken 

 into and was being dug and gradually carted away for agricultural 

 purposes. The marl was pure white, like crumbly chalk, and was 

 almost entirely made up of fresh-water shells, chiefly of the genera 

 Liinncea and Cyclas^ with some others. 



We had not much time at our disposal, and we had no idea that 

 this old lake bottom was unknown to Yorkshire geologists, so we 

 merely marked it down in our maps, noted a few particulars in our 

 books, secured a lump or two of the shell-marl, and went on our way. 

 Since then we have looked up the authorities on West Riding 

 Geology, and find that our little ancient lake is not mentioned by 

 them. Miall's 'Geology of Craven,' Davis & Lees' 'Geology and 

 Botany of the West Riding,' Phillips' quarto classic, and his smaller 

 'Mountains and Rivers of Yorkshire' — none of these said a word 

 about it. Still it might be well-known to some of the many 

 geologists familiar with that delightful region. But the other day our 

 friend. Professor A. H. Green, of the Yorkshire College, informed us 

 that he had never seen or heard of it. This has decided us to put 

 on record our meagre observations, in order that others may not 

 pass by the spot without extending them, and especially without 

 collectmg and identifying the species of the perfectly-preserved but 

 dreadfully friable and fragile shells. 



The old lake is easily found. It is four miles north-west of 

 Settle, about half-way between Horton-in-Ribblesdale and Clapham, 

 and occupies the bottom of the Cnnumach valley between Moughton 

 Fell and Norber. This valley bottom is carved out of hard slaty 

 Silurian rocks, which, close to the marl pit, are seen beautifully 

 polished and grooved in situ by ice, and which at Norber close by, 

 have supplied that wonderful assemblage of ice-carried boulders 

 which stand out so black and sharp against the white weathered 

 mountain limestone scars on which they lie. That the lake bottom 



Naturalist, 



