James Croll — Transport of Wastdale Crag Blocks. 15 



going on all around, and very probably a new centre was produced 

 along quite the south-eastern edge of England. In Oolitic times the 

 two former had probably united to form one western stretch of land, 

 which gradually extended itself eastwards towards the close of that 

 period, while the south-eastern mass of land was depressed, and 

 received deposits upon it. 



In Cretaceous times the land had retreated somewhat westwards, 

 occupying rather more than the present western half of England, 

 and then again during Tertiary ages increased slowly eastwards, 

 until the whole of the present England was represented. 



Lastly, during the Glacial period, such a submergence took place 

 as to leave only parts of the original "Welsh and Cumbrian centres 

 above water, with perhaps a southern mass of land, thus, as it were, 

 restoring the embryonic condition of England for a brief space at 

 the close of its long history. 



In the case of English geological history we have then to observe 

 the following points : — 



1. The geological records date back to Cambrian times, and there 

 is clear evidence of land-centres as far back at least as the Mid- 

 Silurian. 



2. The early land-centres of Wales and Cumberland received 

 depositions of strata around and upon them until the close of the 

 Carboniferous, since which time they have been completely above 

 water, with the exception of the partial submergence of the Glacial 

 period. Thus, England may be considered a much older country 

 than Italy, and to have had a more complex origin. 



3. The long periods during which these two centres have re- 

 mained as dry land, explains the enormous amount of sub-aerial 

 denudation which seems to have taken place ^ in these districts.* 



The study of ancient physical geography, which hitherto has 

 received so little attention, is becoming daily of more and more 

 importance and interest, inasmuch as by its consideration alone shall 

 we probably be able to work out the great question of the succession 

 and distribution of life upon the globe. 



lY. — OiT THE Tkansport of the Wastdale Ckag Blocks. 



By James Croll, of tlie Geological Survey of Scotland. 



CONSIDEEABLB difBculty has been felt in accounting for the 

 transport of the Wastdale Granite Boulders across the Pennine 

 chain to the east. Professors Harkness^ and Phillips,* Messrs. 

 Searles Wood, jun.,^ Mackintosh,^ and I presume all who have 

 written on the subject, agree that these blocks could not have been 



1 " On the Denudation of the Lake District," Geol. Mag., January, 1870. 



" It is curious to think how much older our English mountain districts are 

 than the great ranges of the Alps, the Apennines, the Himalayas, the Andes, and the 

 Eocky Mountains. 



2 Quart. Journ. Geol. Soc. xxvi., p. 517. 



* British Assoc. Keport for 1864 (Sections), p. 65. 



5 Quart. Journ. Geol. Soc, xxvi., p. 90. 



6 Geol. Mag., YII., p. 349. 



