320 HISTORY OF GEOLOGY AND PALAEONTOLOGY. 



it began to form. A detailed account of the Palaeozoic, 

 Mesozoic, and Tertiary oceans, with their transgressions and 

 retrogressions, comprises many new conceptions, and leads the 

 author finally to the consideration of the oscillations of the 

 ocean surface at the present day. The emerging coasts of 

 Scandinavia are viewed as proof of lowered sea-level, and the 

 general opinion in favour of crust-elevation is strongly op- 

 posed. Similarly, Suess explains the strand displacements in 

 progress on the coasts of the Mediterranean Sea, the Pacific 

 and Indian Oceans, as the result of movements in the aqueous 

 envelope of the earth, but not in the solid crust. 



According to Suess, ruptures and collapses affecting the 

 whole thickness of the earth's crust, together with tangential 

 folding of the upper horizons, are the forces to which the earth 

 originally owed its surface conformation. There is no such 

 thing as an active or passive emergence of portions of the 

 earth's crust; in the estimation of Suess, the theory of elevation 

 is a great error. He thinks it impracticable to ascertain the 

 ages of the mountain-systems by any such ingenious method 

 of calculation as Elie de Beaumont attempted, seeing that as 

 a rule the upheaval of a mountain-system occupied protracted 

 intervals of time. Nevertheless, Suess is inclined to correlate 

 the grand physical events of the earth's history with those of 

 the development of the organic world, and thinks it possible 

 in this way to erect a natural and universal classification of the 

 formations. For this purpose it is not so much the origin of 

 new mountain-systems that comes into question as the periodic 

 recurrence of those great pelagic transgressions, whose cause of 

 origin until now has not yet been discovered. 



Many of the hypotheses suggested by Suess will probably 

 not endure the criticism of the future. Yet there can be no 

 doubt that even the expression of a hypothesis having due 

 respect to all known data marks an important step in advance. 

 In the midst of the present activity in conducting detailed 

 investigations there is a certain danger that scientific workers 

 may become parochial in their interests and teaching ; but a 

 work like that of Suess, so cosmopolitan in its standpoint, 

 reminds all workers of their community of aim, rouses each 

 one from the particular to the general, and brings him back 

 with renewed vigour and mental insight to the particular. 

 The time was ripe for an effort to establish systematic clearness 

 in the acquired abundance of detail and to seek for compre- 



