186 J. AITXEN ON THE DISTRIBUTION OF DRIFT 



granite, silurian porphyritic greenstone, and other foreign pebble's 

 occur ; and at and below this point examples of these rocks may be 

 detected in the bed of the river wherever gravel is exposed. This is 

 situated at an elevation of about 200 feet above the sea level. 



At the Elland railway- station, the following section has been 

 exposed by some recent operations of the Company : — 



ft. in. 



Soil 1 4 



Fine subangular gravelly surface wash 2 6 



Loamy sand 6 inches to 1 



Fine sandy gravel 2 6 



Gravel coarser than that above ; stones all waterworn 

 and much abraded, of local origin, resting upon a 



bed of Carboniferous shale 5 



Total 12 4 



At the cemetery, a few hundred yards to the north-west of the 

 last-named place, and at an elevation of about 300 feet, a bed of 

 gravel, sand, and loam, varying in thickness from 5 to 10 feet, ana- 

 logous in character to the section last described, reposes upon the 

 Carboniferous shale. And in the Shibden valley, deposits precisely 

 similar to these are found at about a corresponding elevation. 



In the three last-named instances the stones composing the gravel 

 consist of well-rounded waterworn rocks, derived exclusively from 

 the basin of the Calder and its tributaries, not a foreign pebble being 

 found incorporated with them. This gravel may therefore be re- 

 garded as having a purely local origin, and probably dates from the 

 time when the river ran at this level, and is consequently in no 

 way connected with the glacial drift which occurs in the valley 

 below. 



Precisely analogous conditions to those already described as oc- 

 curring in the Walsden defile exist in the Cliviger valley, the drift 

 running up on the sides of the hills near the entrance of the gorge 

 to a height of 1075 feet, its southerly termination taking place both 

 on the sides of the hills and in the valley in a line almost cor- 

 responding with the summit-level of the latter at Calder Head, which 

 has an elevation of 768 feet. 



It appears from a paper* read some time ago by Mr. R. H. Tid- 

 deman, of the Geological Survey, that a very similar state of things 

 occurs with regard to the distribution of drift in the great water- 

 shed of the north, opening between the basins of the Kibble and 

 the Aire, which has a summit-level of 700 feet. No ice-scratches 

 are shown on the excellent map which accompanies that paper as 

 existing east of the watershed of the Pennine range in that part of 

 the country ; and those which do occur near to that line run, with 

 one exception, in 'a direction closely approaching to north and 

 south. 



* " On the Evidence for the Ice-sheet in North Lancashire and adjacent 

 parts of Yorkshire and Westmoreland," Quart. Journ. Geol. Soc. for Nov. 1872, 

 p. 478, a contribution the value of which it is difficult to overestimate. 



