EDEN VALLEY AND YORKSHIRE -DALE DISTRICT. 65 



vale of York. Probably most geologists will consider such a com- 

 bination of circumstances so very improbable that they will reject 

 the ice -raft theory as entirely untenable. 



It is perhaps unnecessary to bring forward any other arguments 

 to prove that the Brockram cannot have been transported by float- 

 ing ice in any form. 



It has been suggested that the difficulty might be lessened if it 

 could be proved that there had been a considerable upheaval on the 

 escarpment sides of the great faults in Postglacial times — in other 

 words, if it could be proved that in Glacial times there was not so 

 great a difference between the relative levels of the Stainmoor passes 

 and the Eden valley as there now is. That no such Postglacial 

 upheaval can have taken place is clearly enough proved by the fact 

 that wherever the drifts that contain Brockram have lately been 

 removed from the rock, this is always found to be striated, if the 

 rock is of such a kind as to receive and retain scratches ; and these 

 glaciated surfaces are found at nearly equal elevations on both sides 

 of the faults, often within a few hundred yards of the lines of dis- 

 turbance. In addition to this the long mounds of Brockram-bearing 

 drift extend uninterruptedly across the faults in such a way as to 

 show that there cannot have been much, if there has been any, 

 movement on one side or the other of the faults since the drift- 

 mounds were deposited. Lastly, there is nowhere a rock-terrace, 

 even of a few feet, on the escarpment sides of the faults ; on the 

 contrary, wherever the rock- surface is seen, it forms a continuation 

 of the features on the other side of the line of disturbance. Denu- 

 dation in Postglacial times will not account for this, because the 

 drift-mounds before mentioned have been left in what must be very 

 nearly the shape and size they had after the last trace of the ice 

 sheet disappeared. 



If it be conceded that the Brockram cannot have been transported 

 by any form of floating ice over the Stainmoor passes, we are bound 

 to accept the only other theory that will meet the requirements 

 of the case, and conclude with Mr. Croll that here also a great sheet 

 of land-ice has been at work. 



The numerous strice that have been found on the part of Stain- 

 moor over which the Eden-valley drifts can be shown to have 

 passed, indicate clearly enough in which direction the ice was flow- 

 ing ; a glance at the Map will show that they range nearly at right 

 angles to the present lines of equal elevation ; in other words, they 

 point the shortest way to the summit. What yet remains to be 

 accounted for before the land-ice theory can be adopted, is the 

 agency that caused the Eden-valley ice sheet to move, as it has 

 clearly done, from west to east — up hill, instead of along the ordi- 

 nary lines of drainage of the country. Fortunately we have not far 

 to seek for the required evidence. 



Hitherto no mention has been made of any of the rocks that are 

 associated with the Brockram in the Stainmoor drifts. If any thing 

 definite can be made out respecting the means of transportal of any 

 one of the kinds of rock in the drift, it is clear that all the stones 



Q. J. G. S. No. 121. p 



