806 KEroRT— 1892. 



condition. The only great linear uplifts or true mountains of elevation .which have 

 come into existence in Western Europe and North Africa since the Palaeozoic 

 period trend approximately at right angles to the direction of the Atlantic trough, 

 and are obviously related to the primitive depression of the Mediterranean. The 

 Pyrenees and the Atlas, therefore, although their latest elevation took place in 

 Tertiary times, form no exceptions to the rule that the extreme flexing and folding 

 of strata which is so conspicuous a feature in the geological structure of the 

 Atlantic sea-board dates back to the Paheozoic era. And the same holds true of 

 North and South America. There all the coastal ranges of highly flexed and folded 

 strata are of Palaeozoic age. The Cordilleras of Venezuela are no doubt a Tertiary 

 uplift, but they are as obviously related to the Caribbean depression as the Atlas 

 ranges are to that of the Mediten'anean. Again, we note that volcanic activity 

 along the borders of the Atlantic was much less pronounced during the Mesozoic 

 period than it appears to have been in earlier ages. Indeed, if we except the great 

 Tertiary basalt-flows of the Icelandic ridge and the Arctic regions, we may say that 

 volcanic action almost ceased after the PaL-eozoic era to manifest itself upon the 

 Atlantic coast-lands of North America and Europe. But while volcanic action has 

 died out upon the Atlantic margins of both continents, it has continued during a 

 prolonged geological period within the area of the Mediterranean depression. And 

 ill like manner the corresponding depression between North and South America 

 has been the scene of volcanic disturbances from Mesozoic down to recent times. 

 Along the African coasts the only display's of recent volcanic action that appertain 

 til the continental margin are those of the Gulf of Guinea and the Cape de Verde 

 Islands. The Canary Islands and Madeira may come under the same category, but, 

 as we have seen, they appear to stand in relationship to the Mediterranean depres- 

 sion and the Tertiary uplift of North Africa. Of Iceland and the Azores I have 

 already spoken, and of Ascension and the other volcanic islets of the South Atlantic 

 it is needless to say that they are related to wrinkles in the trough of the ocean, 

 and therefore have no immediate connection with the continental plateau. 



Thus in the geographical development of the Atlantic coast^lines we may 

 note the following stages: — First, in P.alieozoie times the formation of great 

 mountain-uplifts, frequently accompanied by volcanic action. Se.cotid, a pro- 

 longed stage of comparative coastal tranquillity, during which the maritime ranges 

 referred to were subject to such excessive erosion that they were planed down to 

 low levels, and in certain areas even submerged. Third, renewed elevation (nega- 

 .tive or positive) whereby considerable portions of the much denuded Archaean and 

 Palaeozoic roclis, now largely covered by younger deposits, were converted into 

 high lands. During this stage not much rock-folding took place, nor were any 

 true mountains of elevation formed parallel to the Atlantic margins. It was 

 otherwise, however, in the jMediterranean and ('aribbean depressions, where coastal 

 movements resulted in the formation of enormous linear uplifts. Moreover, Tol- 

 canic action is now and has for a long time been more characteristic of these 

 ■depressions than of the Atlantic coast-lands. 



I must now ask you to take a comprehensive glance at the coast-lines of the 

 Pacific Ocean. In some important respects these ofl'er a striking contrast to those 

 wo have been considering. Time will not allow me to enter into detailed descrip- 

 tion, and I must therefore confine attention to certain salient features. Examining 

 first the shores of the Americas, we find that there are two well-marked regions of 

 fiords and fringing islands — namely, the coasts of Alaska and British Columbia, 

 and of South America from 40° S. lat. to Cape Horn. Althougli these regions 

 may be now extending seawards in jilaces, it is obvious that they have 

 recently been subject to submergence. When the fiords of Alaska and British 

 Columbia existed as land valleys it is probable that a broad land connection 

 obtained between North America and Asia. The whole Pacific coast is margined 

 by mountain-ranges, which in elevation and boldness far exceed those of the 

 Atlantic sea-board. The rocks entering into their formation range in age from 

 Arc])03an and Palaeozoic down to Cainozoic, and they are almost everywhere 

 highly disturbed and flexed. It is not necessary, even if it were possible, to 

 consider the geological history of all those uplifted masses. It is enough for my 



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