DYNAMICAL GEOLOGY. 319 



The first volume concludes with a summary of the most 

 important results obtained throughout the work.' It is 

 pointed out that the names Old and New World are, geo- 

 logically speaking, quite unjustified, as the greater part of 

 North America has been exposed as dry land since the 

 Cretaceous epoch, and is therefore of considerable antiquity. 

 South America has its own distinct structure ; it may be 

 described as a gigantic crust-buckle bounded on three sides 

 by high mountain-walls, but unbroken by any tectonical lines 

 towards the east and north-east. 



In the Old World three dissimilar regions have been welded 

 together: (i) the southern parts of the ancient Gondwana 

 Land, which has never been completely submerged since the 

 conclusion of the Carboniferous epoch ; (2) Indo-Africa, the 

 present Sahara, Egypt, Syria, and Arabia, covered by the ocean 

 in the Cretaceous epoch, but never subjected to folding-move- 

 ments since Palaeozoic time ; and (3) Eurasia, the north-west 

 of Africa, Europe, and the remainder of Asia. The southern 

 borders of Eurasia are strongly folded, and throughout long 

 tracts they have been thrust above the Indo-African table-land. 



The second volume begins with a historical account of the 

 different opinions regarding secular movements of upheaval 

 and depression of the land. Suess points out the advantages 

 of the terms "positive" and "'negative" as signifying the 

 relative character of coastal displacements (ante, p. 292). 



Two of the most brilliant chapters in the work are devoted 

 to the boundaries of the Atlantic and Pacific Oceans. All the 

 erudition of a century is summed up in these pages; as one 

 reads, broad geological portraits of the face of the earth as it is 

 and as it was are called forth, till one forgets to marvel at the 

 magician's touch or question the individual features. A com- 

 parison of the North European and North American fault-areas 

 discloses unexpected homologies between the two territories. 

 The re-construclion of the ancient Armorican and Variscan 

 mountain-systems in Central Europe, the elucidation of their 

 losses by fracture and denudation, and the proof of the 

 similarity in the direction of the later folding that gave origin 

 to the Alps and Pyrenees, are masterpieces of scientific 

 argument. 



The Face of 1he Earth is intended, however, not only to 

 explain the origin of mountains, but also to trace in chrono- 

 logical succession the chief vicissitudes of the solid crust since 



