66 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



associated with the works of man near Bedford, Abbeville, Salisbury, 

 and other localities, so that we are enabled to correlate the gravel of 

 the river Aire with that of a number of rivers which appear to have 

 risen in times of floods from 40 to 80 feet above their present ordinary 

 level in that part of the Quaternary period which I term the " Pluvial 

 period " (Quart. Journ. Geol. Soc. vol. xxiv. pp. 105, 120). 



The Cyrena Jlumindlis or consobrina is found in the gravels abun- 

 dantly at St. Yalery, at the mouth of the river Somme, in Picardy, 

 and also in the estuary of the Humber at Kelsey Hill. The Aire 

 flows into the Humber. 



There is, as might be expected, great diff'erence in the materials 

 of which the respective gravels are composed, arising from the dif- 

 ferent character of the rocks over which the rivers flow, and from 

 the greater fall of the Aire in its course, from its source to the sea, 

 than that of the Somme. The important stratified valley-gravel at 

 Abbeville, containing numerous species of shells, is represented 

 by the Kelsey-Hill and Hessle beds near the mouth of the Humber at 

 a similar height above the river. The width of the valleys is not so 

 diflerent as their depth ; but this is due, as before stated, to the diflfer- 

 ence in the fall of water per mile in the two rivers Somme and Aire. 



There is no good section of gravel now open at Bingley. The 

 limestone boulder-pits have been filled up many years ; and the rail- 

 way is carried near the present river, or in an old secondary river- 

 course of the gravel-period. 



Glamorganshiee Gravels. 



I shall now describe some measured sections of very thick and 

 important river- gravels in the valleys of the rivers Taff, Rhondda, 

 and Cynon, in Glamorganshire, South Wales. 



A longitudinal section of the river Taff would show the rapid 

 character of the river, which falls nearly 500 ft. between Merthyr 

 Tydvil (A, fig. 3) and the sea at Cardiff, about twenty miles. The 

 following heights of the bed of the river Taff, above the coping of 

 Bute Dock, Cardiff, were kindly furnished me by Mr. George Pisher, 

 Engineer in chief, Taff- Yale Railway. These heights were the only 

 ones sent to me relating to the river Taff. Their exact position on 

 the map was also laid down by Mr. Eisher himself, and fig. 3 is a care- 

 fully reduced copy of his map. The coping of Bute Dock is 9-82 ft. 

 above the level of ordinary spring tides. 



Plate y. is a plan of the river Taff', near Quaker's-Yard Junction. 

 PI. lY. fig. 1 represents a long section opened out by the Taff Yale 

 Railway (ABC), the position of which is shown on the plan (PI. Y.). 

 The heights at different points have been kindly determined by Mr. 

 L. T. Lewis, P.G.S., of Aberdare, or by Mr. G. Fisher, of Cardiff, and 

 are marked on the section. 



The plan and section of the valley of the Taff, between Quaker's- 

 Yard Junction and Aberdare Junction of Taff Yale, represent 

 about one mile in length by two -thirds of a mile broad. The 

 height of the point of the sandstone-rock forming the crown of 

 the hills is about 275 feet above the level of the Taff at Aberdare 



