G26 T. W. VAUGHAX GEOLOGIC HISTORY OF CEXTRAL AMERICA 



ward Passage. A downthrowii block between these lines has separated 

 Cuba and Haiti and produced the Bartlett Deep. Probably there was also 

 faulting or flexing between Cayman Eidge and the southern shore of 

 Cuba west of Manzanillo Bay, while either faulting or flexing may have 

 separated Cuba and Yucatan. There is evidence of a downthrown fault 

 ])lock between Saint Thomas and Saint Croix, the two sides converging 

 toward Anegada Passage. This will account for the deep of over 2,400 

 fathoms north of Saint Croix, and the severance of Saint Croix and the 

 Saint Martin Plateau group of islands from the Virgin group. 



There are three kinds of evidence that bears on the age of these faults, 

 namely: (1) In eastern Cuba, as the Miocene La Cruz marl is abruptly 

 cut off at the shoreline in the vicinity of the Morro, at the mouth of 

 Santiago Harbor, the faulting must be subsequent to old or middle Mio- 

 cene; (2) as the sea along fault shores has been able subsequent to the 

 faulting to cut only narrow benches into the fault-planes on the up thrown 

 side, the fault-planes are physiographically young: (3) the biologic evi- 

 dence, in the opinion of most of those who have recently considered it, 

 demands land connection in late Tertiary time between Cuba, Santo 

 Domingo, Porto Rico, and thence to South America. Miller has recently 

 published an important paper on this subject,^^ and states : 



"With the characters of so many [eight] genera known it becomes possible 

 to gain some idea of the Antillean hystricine fauna.^^ The most noticeable 

 feature of these genera, considered as a group, is their similarity to tlie Santa 

 Cruzian and Entrerian rodents which Ameghino and Scott have described and 

 figured. In no instance has the same genus been found in both the West Indies 

 and Argentina or Patagonia; but the Antillean rodents thus far discovered 

 never show such peculiarities that their remains would appear out of place 

 among those of their extinct southern relatives, while as a whole they would 

 at once be recognized as foreign to the present South American fauna." 



On the following page of the same paper he says : 



"So far as can be judged from eight" very distinct genera, the Antillean 

 hystricine rodents do not present the characters that would be expected in 

 animals derived from South America during any period geologically recent. 

 Neither have they the appearance of an assemblage brought together at differ- 

 ent times by migration or chance introduction. On the contrary, they suggest 

 direct descent from such a part of a general South American fauna, probably 

 not less ancient than that of the Miocene, as might have been isolated by a 

 splitting off of the archipelago from the mainland. Of later influence from 

 the continent there is no trace." 



" Gerrit S. Miller, Jr. : Bones of mammals from Indian sites in Cuba and Santo Do- 

 mingo. Smithsonian Misc. Coll., vol. 66, no. 12, 1916, 10 pp., 1 pi. 



12 Op. cit., p. 3. 



13 "Two more were described by Anthony in January, 1917. They bear out my state- 

 ment about the eight and make it stronger. — G. S. M., Jr." 



