€20 EEPOiiT— 1886. 



suggests that a narrow strait running in a northerly direction may have insulated 

 the Palaeozoic rocks beneath the Loudon district. The clays of the Lias, Oxfordian, 

 and Kimmeridgian probably indicate a direct discharge of sediment into the sea/ the 

 limestones, depression sufficing to convert valleys into fjords, in the upper parts of 

 vrhich sediment was deposited so that the waters of the sea were clear. The 

 deposits of the Purbeck and Weald indicate that the western river stiU drained an 

 extensive area, and a gradual rise of land in later Jurassic times, especiaUj' towards 

 the south, appears to have advanced the river delta eastwards, and to have limited 

 the area of the Jurassic sea on the north. 



Towards the end of the Xeocomian, owing to a widespread subsidence, the sea 

 once more returned to South-eastern England, and a communication appears to have 

 been opened between it and the Speeton basin. This comparatively narrow strait 

 was a region of considerable denudation and of strong and shifting coast currents.- 

 The Cretaceous subsidence at first brought back physical conditions not very different 

 from those prevalent in Oxfordian and Kimmeridgian times, but later on a very 

 considerable depression must have so far submerged the northern continental land 

 as either to break up the parts adjacent to Britain into groups of islands, or at 

 least to flood the valleys so completely as to prevent any discharge of sediment into 

 the sea. The erratics of the Cambridge Greensand suggest that a free communica- 

 tion into the northern ocean was establi.shed, anterior to the formation of the Chalk 

 marl, through some part of the present interval between Scotland and Scandinavia, 

 so as to set up a coast current with a southerly drift of shore ice near the eastern 

 part of England: to this also may be due the erosion of the Cambridgeshire 

 Gault. 



The larger part of Britain was dry land during the Eocene, though the sea after 

 retreating appears to have again encroached over the southern and eastern districts 

 of England. The sands may indicate that the western river again resumed its 

 course ; ^ the extension of the London Clay up our eastern coast suggests that the 

 nurthern river still flowed. But with the important disturbances which closed the 

 Eocene and ushered in the continental conditions of the Miocene — new flexures 

 along the old east and west lines — the earlier physical features appear to have been 

 finally obliterated, and the sculpture of the English lowlands began. The tale of 

 the volcanic outbursts of Western Scotland has been so well told by my friend and 

 predecessor Professor Judd that I need do no more than recall it to your minds. 

 The Pliocene deposits of Eastern England indicate a new encroachment of the 

 Eranco-Belgian Tertiary sea. 



Thus ends my sketch — too lengthy, I fear, for your patience, yet too brief to 

 allow of a complete treatment of the subject. It may, however, suffice to indicate 

 that in geology the ' task of the least ' is by no means despicable, and that great 

 results may be hoped from apparently small means; that in this search for 

 ' Atlantis through the microscope ' we may find it very near at hand, and may 

 discover analogies, as has been indicated in our President's address, between the 

 two borders of the ocean which severs Europe from America. An enlarged study 

 of the materials of our Palfeozoic and later detrital rocks may indicate tbat from 

 very early times there has been a reciu-rence of similar physical conditions, and that 



' The considerable distance to which the clays extend in a southerly direction 

 may possibly indicate that, to the east of Scotland, a communication had now been 

 opened with the northern ocean, which had set up a current along the coast east of 

 the Pennine chain. 



^ As the Speeton beds continue to be clays one would infer a drift from the 

 south, but a current to the opposite direction would be more probable, and it is the 

 opinion of Dr. Sorby that this was the case. His papers ' On the Direction of the 

 Currents indicated by the Coarse Sediments in our British Rocks ' are most valuable 

 ( Yorks. Geol. Pol. Soc. v. 220, kc.) A pebble bed sometimes occurs at the base of 

 the Portland series, apparently resembling, though on a very small scale, those in the 

 Neocomian. 



^ The occasional beds of flint pebbles indicate a neighbouring shore line of Cre- 

 taceous rocks rather than the denudation of beds of Cretaceous age, which had been 

 deposited on parts of the western land during the period of depression. 



