128 John Gunn — Changes of Clinude. 



and other districts are carried sea-ward bears most importantly on 

 the geology of the county of Norfolk. Precisely as Lyell describes 

 them, the Boulder-claj'S with striated rocks, and containing arctic 

 shells, appear to have been stranded and impinged upon the shores 

 of the eastern coast. A striking instance of this, north of Cromer, 

 was pointed out on an excursion of the British Association in 1868, 

 ■where an iceberg seems to have driven up the Laminated beds, and 

 as a proof that they bad been imported from the north-east, it may 

 be stated, on the authority of Mr. Lartet, that no Boulder-clays are 

 discovered on the French coast or in France. 



The effects produced by these glaciers and icebergs appear to 

 belong to the concurrent agency of the elevation of mountain 

 heights, and Processional movements, and it is difficult to separate 

 the one from the other. In this country we may observe the peaks 

 of mountains, which have never been submerged, projecting above 

 the lowlands, as it were islands above the sea, just as islands may be 

 observed rising above the Pacific Ocean. 



In order to understand what the Northern Hemisphere has under- 

 gone, we may with advantage turn our attention to what is now 

 passing in the Southern Hemisphere. So far as its condition can be 

 made out through the observations of voyagers and charts, there 

 appears to be a reproduction of the so-called Glacial epoch, just as 

 it prevailed in the Northern Hemisphere. There is the like over- 

 spread of ice and snow, and numerous islands exist in the adjacent 

 ocean, which, if upraised, would form the mountains of a continent 

 or vast tract of land, so that it is difficult not to recognize a corre- 

 spondence between the present condition of the Antarctic and that of 

 the Arctic dm-ing the Glacial epoch. 



This correspondence is well described by the Eev. W. S. 

 Symonds, F.G.S., in his admirable treatise on the " Severn Straits," 

 page 51. 



" The Antarctic Continent," he observes, " may be said to be passing 

 through a Glacial epoch. Ships cannot pass the 70° of latitude for 

 ice, and the Antarctic lands are not known to possess a single land 

 animal. The Ice King reigns everywhere. 



'"What the Antarctic regions are now, the Arctic regions of the 

 distant north must have been during the Glacial periods, and the 

 musk-ox, the polar bear, the walrus, and the rein-deer, must have 

 migrated southwards, for they could not have existed there." 



With respect to the causation of these Glacial phenomena at either 

 Pole, we have a remarkable and beautiful coincidence of cause and 

 effect, the greater length of the earth's orbit traversed in the summer 

 portion, compared with that traversed in the winter portion, causes 

 an alternate increase and diminution of heat and cold in the two 

 hemispheres, as we have seen, and a corresponding change in the 

 Fauna and Flora. 



Still it must be allowed that there is an excessive irregularity to 

 be accounted for, arising from the conjoint action of the uniform and 

 unvarying Processional movements, and the changes of climate 

 induced by the elevation of mountain-ranges. 



