190 THE LAW. 



cataclysmal irregularity in Creation, so we are led to infer 

 the prior occurrence of such glacial periods at determinate 

 times and over determinate areas. The existence of such 

 glacial recurrences has been surmised by several geologists 

 as characterising the periods of the old red sandstone and 

 Permian ; * and we may venture to extend them to other 

 systems as probable features of a great cosmical plan. 



Thus, looking at the Cambrian strata of the northern 

 hemisphere their angular grits and conglomerates, their 

 extreme paucity of fossil forms, and other features we are 

 at once reminded of the action of ice and the presence of 

 ungenial conditions. This is followed over the same areas 

 by the more genial and exuberant period of Siluria ; which 

 is in turn succeeded by the old red sandstone, whose grits 

 and bouldery conglomerates, as well as paucity of vegetable 

 forms, once more suggest the recurrence of colder influences. 

 Following the old red we have the exuberant flora and 

 fauna of the coal period, again to be succeeded by the scanty 

 life-forms and grits and conglomerates of Permia. Again, 

 the trias and oolite of the northern hemisphere are charac- 

 terised by life-forms that betoken warm and genial condi- 

 tions; while the chalk that succeeds imbeds water-worn 

 blocks of granite and lignite, which would seem to imply 

 the presence of ice-drift and deposit in seas that were 

 open to boreal influences. Next the early tertiaries occur 

 over the same areas, marked by plants and animals that in- 

 dicate a warm and genial climate ; and this in turn gives 

 place to the well-known glacial or boulder-drift epoch ; 

 once more to be succeeded by the milder influences of the 

 post-tertiary or current era. Throwing these recurrences 

 into diagrammatic form, we appear to have had an alter- 



* Mr Gumming, in History of the Isle of Man (1848) ; Mr Goodwin- 

 Austen, Geological Journal (1850); Professor Ramsay, Ibid. (1855); 

 and the author, in his Advanced Text- Book. 



