ANTILLEAN-CARIBBEAN REGION 



695 



j 



Fig. 42.12. Strike-slip faulting in Greater Antilles. Hy- 

 pothesis of Hess and Maxwell (1953) showing presumed 

 positions before and after horizontal translation. 



' 



pression in the contours of the sea floor, as in the Anegada Passage . . . and 

 again west of St. Croix; in the Beata Ridge and its northeastward continuation 

 along the south coast of Santo Domingo, northeast of Cape Beata; in the 

 Navassa-Jamaica Passage (Bucher, 1952, p. 83). 



Since the seismic data essentially preclude the existence of a major 

 itectogene in the Lesser Antilles, the need for large-scale eastern movement 

 of the Caribbean block is mostly dissipated. Also since the seismic data 

 of the Cayman trench indicate considerable stretching of the crust, the 

 fwrench fault hypothesis hardly seems compatible with so much tensional 

 strain. In fact, both the tectogene and wrench faults were conceived 

 before the seismic refraction surveys, and they do not account for the 

 crustal structure that the surveys reveal. The postulated wrench fault 



pattern of the Colombian and Venezuelan coast is fairly impressive, but 

 yet some of the assumed relations are rather tenuous. In the continental 

 drift hypothesis South America because of its present position appears 

 to have moved eastward as well as southward while main tainin g a north- 

 south orientation. If so, considerable eastward shearing could have oc- 

 curred along the Greater Antillean alignment. But at the same time tin- 

 north coast of South America should have moved eastward also relative 

 to the Caribbean block, and this is just opposite to the direction indicated 

 by the postulated wrench fault pattern. 



The origin of the Gulf of Mexico and the Antillean region is still un- 

 known. 



