is M _iSSo] GLEN ROY 1 93 



then water would escape from an outlet at Loch Spey, and Lettei 530 



the highest shelf would be first formed. Secondly, ice be 



to retreat, and water will flow for short time over its surface; 



hut as soon as it retreated from behind the hill marked Craig 



Dhu, where the outlet on level of second shelf was discovered 



by Milne, 1 the water would How from it and the sec 



shelf would be formed. This supposes that a vast barrier 



of ice still remains under Ben Nevis, along all the lower 



part of the Spean. Lastly, I suppose the ice disappeared 



everywhere along L. Loggan, L. Trcig, and Glen Spean, 



except close under Ben Nevis, where it still formed a barrier, 



the water flowing out at level of lowest shelf by the Pass 



of Mukkul at head of L. Loggan. This seems to me to 



account for everything. It presupposes that the shelves were 



formed towards the close of the Glacial period. I come up 



to London to read on Thursday a short paper at the Linncan 



Society. Shall I call on Friday morning at 9.30 and sit 



half an hour with you ? Pray have no scruple to send a line 



to Queen Anne Street to say " No" if it will take anything 



out of you. If I do not hear, I will come. 



To J. Prestwich. Ut{eT 53 , 



Down, Jan. 3rd, 1SS0. 

 You are perfectly right.- As soon as I read Mr. Jamie- 

 son's article on the parallel roads, I gave up the ghost with 

 more sighs and groans than on almost any other occasion in 

 my life. 



IV. Coral Reefs, Fossil and Recent, 1841-81. iter 532 



To C. Lyell. 



Shrewsbury, Tuesday, 6th [July, 1841]. 

 Your letter was forwarded me here. I was the more glad 

 to receive it, as I never dreamed of your being able to find 

 time to write, now that you must be so very busy ; and I 

 had nothing to tell you about myself, else I should have 

 written. I am pleased to hear how extensive and successful 

 a trip you appear to have made. You must have worked 



1 See note 2 on Letter 521, p. 1S1. 



s Prof. Prestwich's paper on Glen Roy was published in the Phil. 

 Trans. R. Soc. for 1S79, p. 663. 



VOL. II. 13 



