94 



PEOF. J. LOGAN LOBLEY, F.G.S., F.E.G.S., ON 



With the object of inviting the Institute to this fuller con- 

 sideration of a most important subject, I have here briefly 

 brought together some of the data which appear to l:>e necessary 

 to form a sufficiently stable and wide basis for a sound conclusion. 



In the consideration, however, of the results of palseontological 

 observation and research, we ought never to lose sight of that most 

 important truth that all the geological data available, and all 

 that ever will be available, for our use nnist be but a most 

 imperfect record of the past. The fossiliferous rocks now exist- 

 ing are but the remnants that have been left of those vast accumu- 

 lated deposits formed in the past after having been subjected 

 for enormously prolonged periods of time to the action of the 

 disintegrating forces of nature. 



Thus, for example, not to go further than our own well known 

 islands of Great Britain and Ireland, the Jurassic rocks, now 

 restricted, to the south-east side of a line from Axmouth, in 

 Devonshire, to the mouth of the Eiver Tees, have left small 

 remnants in the Hebrides and Sutherlandshire to attest their 

 former extension over parts of the area that is now Great Britain. 

 The Cretaceous rocks, now confined to the southern and eastern 

 counties, have similarly left small remnants in Mull and 

 Morven on the west and fossils near Aberdeen on the east of 

 Scotland ; and as far north-west as Antrim, in Ireland, the 

 uppermost formation of the Cretaceous, the Chalk, is found 

 preserved by a protecting overlying sheet of volcanic basaltic 

 rock, from which it is seen that this formation once extended 

 over what is now part of England and the Irish Sea and away 

 to the extreme north of Ireland. A small outlier of the 

 "Woolwich Beds at Newhaven, on the coast of Sussex, shows the 

 former extension of Tertiary deposits over the whole area of the 

 older Cretaceous rocks now forming the surface between Croydon 

 and the south coast. At St. Erth, in Cornwall, there are remnants 

 of Pliocene deposits 290 miles west of the nearest beds of this age. 



While, therefore, the Jurassic rocks now spread over only the 

 Midlands and the south and east of England, there is evidence 

 that they once covered nearly the whole area now included in 

 the British Islands and adjacent seas,* and that the Cretaceous 

 rocks, now confined to a still more limited area, had an equal, 

 if not greater, extension, while the Tertiaries furnish grounds 



^ Hi<,^lily improbable that the Jurassic rocks extended over North 

 Wales, the Lake J)istrict, the Border Hills of Scotland, and the Highhind 

 Mountains, or tliat tlie Cretaceous rocks extend over these regions. See 

 my J'lii/iiical iliatory of the British Isles, — Ed. 



