REVIEWS 129 



It is gratifying to find that Dr. W. Bergt supports unreservedly the 

 Archean age of the nucleal axes of the Caribbean islands in the follow- 

 ing words :' 



Das archaische Alter, welches, P. Frazer fiir die Centralketten des siidost- 

 lichen Cuba feststellen konnte, und das er fiir ganz Jamaika, fiir San Domingo, 

 Puerto Rico, und die Windwardinseln vermuthete, kann nunmehr bestimmter 

 fiir San Domingo angenommen werden. 



It may be, as Mr. Hill suggests, that no " Paleozoic nucleal rocks" 

 have been established with certainty in "Cuba and Santo Domingo" 

 or any other of the border lands of the "American Mediterranean " 

 {Cul)a and Porto Rico, p. 384) although de Castro imagined he had 

 discovered such near Cienfuegos, yet this fact would not invalidate the 

 evidence that part of these nucleal rocks are pre-Cambrian. 



And one purpose of this paper is to recall the fact that we have 

 proofs of physical connection with the western continent of these 

 outlying islands not only from the physiographic features, drowned 

 valleys, submerged plateaus, trend of conformation through the major 

 axes of the present detached islands, paleontological analogy with 

 South American forms of life, etc., but, in addition to all these, the 

 close petrographical relationships of the crystallized and crystalline 

 rocks and their congeners with those of the main land. 



The island of Cuba seems to be constructed of an original igneous 

 mass, diorite, on which clastic rocks, including mica-schists which 

 may be Paleozoic, and sandstones and limestones of Mesozoic and 

 recent ages, are deposited without apparent effects of metamorphism. 

 Through all these are veins of newer eruptives which have generally 

 altered the rocks they have fissured, /. e., giving crystalline character 

 to the radiolarian limestones lifted since Cretaceous time out of the 

 adjacent seas, producing magnetite in the iron-oxides derived in part 

 from the pyrite, changing to quartzites the siliceous slates, etc. 



The lithological character, great alteration, complexity of the 

 series, analogies in paragenesis and alteration-products with rocks of 

 Archean areas in various distant parts of the earth's surface, and the 

 physiographic relations of the greater and lesser Antilles to the 

 peninsula of Yucatan and to Venezuela, suggest a physical connection 

 with the South American continent, and a former American Mediter- 

 ranean (Caribbean) sea. 



These conclusions are in harmony with those of Professor Crosby, 

 Professor J. W. Spencer, and Mr. R. T. Hill, and are specifically con- 

 firmed by Dr. Bergt {supra). They constitute a reinforcement of the 



