92 KEPOUT— 1886. 



earlier geological ages, as might have boon anticipated from the imper- 

 fect development of the continents, the same forms of life charactoriHe 

 the whole ocean from Australia to Arctic Amoric! ind indicate a grand 

 unity of Pacific and Atlantic life not equalled in later times,' and which 

 speaks of contemporaneity rather than of what has been termed homo, 

 taxis. 



We may pause here for a moment to notice some of the effects of 

 Atlantic growth on modern geography. It has given us rugged and 

 broken shores composed of old rocks in the north, and t wer formations 

 and softer features toward the south. It has given us «,re:inal moun- 

 tain ridges and internal plateaus on both sides of the sea. ft has pro- 

 duced certain curious and by no means accidental correspour^c, ^et* of the 

 eastern and western sides. Thus the solid basis on which tlie British 

 Islands stand may be compared with Newfoundland and Labrador, the 

 English Ghannel with the Gulf of St. Lawrence, the Bay of Biscay with 

 the Bay of Maine, Spain with the projection of the American land at 

 Cape Hatteras, the Mediterranean with the Gulf of Mexico. The special 

 conditions of deposition and plication necessary to these results, and their 

 bearing on the character and productions of the Atlantic basin would 

 require a volume for their detailed elucidation. 



Thus far our discussion has been limited almost entirely to physical 

 causes and effects. If we now turn to the life history of the Atlantic, 

 wo are mf at the threshold with the question of climate, not as a thing 

 fixed and immutable, but as changing from age to age in harmony with 

 geographical inutations, and producing long cosmic summers and winters 

 of alternate warmth and refrigeration. 



We can scarcely doubt that the close connection of the Atlantic and 

 Arctic oceans is one factor in those remarkable vicissitudes of climate ex- 

 perienced by the former, and in which the Pacific area has also shared in 

 connection with the Antarctic Sea. No geological facts are indeed at first 

 sight more strange and inexplicable than the changes of climate in the 

 Atlantic area, even in comparatively modem periods. We know that in 

 the early Tertiary perpetual summer reigned as far north as the middle 

 of Greenland, and that in the Pleistocene the arctic cold advanced, nntil 

 an almost perennial winter prevailed, half way to the equator. It is no 

 wonder that nearly every cause available in the heavens and the earth has 

 been invoked to account for these astounding facts. 



It will, I hope, meet with the approval of your veteran glaciologist 

 Dr. Crosskey if. neglecting most of these theoretical views, I venture 

 to invite your attention in connection with this question chiefly to the old 

 Lyellian doctrine of the modification of climate by geographical changes. 

 Let us, at least, consider how much these are able to account for.^ 



' Daintree andEtheridge, 'Queensland Geology,' Journal Geological Society, August 

 1872 ; R. Etheridge, Junior, • Australian Fossils,' Trans. Phys. Soc, Edin. 1880. 

 ' The late Mr. Searlcs V. Wood, in an able summary of the possible causes of the 



