168 SUR VE Y OF THE SNO WDON REGION CHAP, v 



as far as Aber, getting all Jukes's ugly bits of sand- 

 stone, etc., perfectly explained a succession of domes 

 cut off by faults. Home at half- past seven a long, 

 long walk. 



' i2th. Up by the coach to Cwm Idwal. At 

 the top we found a splendid haul of fossils, and I 

 made a grand discovery respecting the drift. [He 

 here gives the section across Llyn Idwal, afterwards 

 published in Quart. Journ. Geol. Soc. vol. viii. (1852), 

 p. 375, showing the drift capping the summits above 

 the lake and a moraine forming the barrier of the 

 water]. The moraines of these valleys are subse- 

 quent to the drift, because, if previous, they would 

 have been smothered in it. But, as I before proved, 

 the roches moutonndes are previous to it, because they 

 are covered by it up to great heights. The drift on 

 top of Cwm Idwal is 2500 feet high, and it reaches 

 probably a parallel height on Cwm Llafar, being 

 thence connected all the way with the drift of the 

 sea-side.' 



By the end of this month he was at Dolgelli, 

 helping Selwyn to put some finishing touches to the 

 mapping of the Cader Idris region. On the I2th 

 October he was able to make to Salter an important 

 announcement touching the troublesome regulation 

 as to receipts for travelling charges. ' Henceforth 

 and for ever you take no more receipts for travelling 

 expenses, and in place thereof you must make out 

 a travelling charges bill. I've got it all in right order, 

 and by a magnificent stroke of genius have got Sir 

 Henry's formal consent thereto.' 



His colleague Oldham had determined to resign 

 the charge of the Irish Geological Survey, and to 

 accept the direction of the Geological Survey of 



