Geological Society of London. • 139 



In this paper, which is a continuation of a former note laid before 

 the Society (see Quart. Journ. GeoL Soc, xxvii., p. 109), the author 

 commenced by stating that his former opinion as to the Jurassic age 

 of the rocks of Antequera is fully borne out by later researches upon 

 their fossils. They apparently belong to the Portlandian series. 

 The author made considerable additions to his description of the 

 Torcal, near the foot of which he has found a sandstone containing 

 abundance of Gryphma virgula and Ostrea deltoidea. This he regards 

 as equivalent to the Kimmeridge Clay. In the Torcal he has also 

 found a soft, white, calcareous deposit, overlying the limestones of 

 supposed Portlandian age, and containing a fossil which he identifies 

 with the Tithonian Terebratula dtphya. The author discussed the 

 peculiar forms assumed by the rocks of the Torcal under denudation, 

 which he supposed to be due originally to the upheaval caused by the 

 rising of a great mass of greenstone, portions of which are visible at 

 the surface on both sides of the range. 



2. " On the Eiver-oourses of England and Wales." By Prof. A. 

 C. Eamsay, LL.D., F.E.S., F.aS. 



The author commenced by describing the changes in the physical 

 conformation of Britain during the Jurassic and Cretaceous periods, 

 and the relations which the deposits found during those periods bore 

 to the Paleozoic rocks of Wales and the north-west of England, 

 He stated that the Miocene period of Europe was essentially a con- 

 tinental one, and that it was closed by important disturbances of 

 strata in central Europe, one effect of which would be to give the 

 Secondary formations of France and Britain a slight tilt towards the 

 north-west. To this he ascribed the north-westerly direction of 

 many of the rivers of France ; and he surmised that at this period 

 the rivers of the middle and south of England also took a westerly 

 course. The westerly slope of the Cretaceous strata of England 

 was also, he considered, the cause of the southern flow of the Severn, 

 between the hilly land of Wales and the long slope of chalk rising 

 towards the east. The Severn would thus establish the commence- 

 ment of the escarpment of the Chalk, which has since receded far 

 eastward. 



The author believed that after the Severn had cut out its valley 

 the Cretaceous and other strata were gradually tilted eastwards, 

 causing the easterly course of the Thames and other rivers of 

 southern and eastern England. In these and other cases adduced 

 by the author, the sources of these rivers were originally upon the 

 Chalk near its escarpment and it is by the recession of the latter 

 (which was followed by the formation of the Oolitic escarpment) 

 that its present relation to the river-courses has been brought about. 

 The author also referred to the courses followed by the rivers of the 

 more northern part of England, and indicated their relations to the 

 general dip of the strata. 



Discussion. — Mr. Hughes pcanted out tliat in Wales and the Lake-district, which 

 in this question might be considered as one, there were two plains of marine denuda- 

 tion, the one referred to by Prof. Ramsay averaging a little over 2000 feet, and the other 

 about 3000 feet above the sea. Such plains get eaten back and cut up into valleys, 



