666 W. D. MATTHEW ORIGIN OF THE ANTILLEAN MAMMALS 



5. The geolog}^ of the Caribbean region appears to me to afford no 

 positive evidence against nnion of the Antilles either with South America 

 or Central America; but neither does it afford any evidence that there 

 ever was such union. Undoubtedly there is a line of disturbance and 

 uplift along the Lesser Antilles, and another stretching through Haiti 

 and Jamaica to Nicaragua; but evidence of similar and contemporaneous 

 upheavals and similar sedimentation in two portions of this line of dis- 

 turbance that are now separated by abyssal depths does not in the least 

 prove that the intervening depths were formerly continuous land bridges. 

 They may have been, but I do not see how any geologic evidence can prove 

 that they were so. If we have evidence from some other source that there 

 must have been a land bridge somcAvhere, then these lines of disturbance 

 shoAv its most probable location. That is all. 



Land union with Florida appears to be distinctly against the geologic 

 evidence, as in this region we have extensive flat-lying Tertiary marine 

 and littoral formations which indicate that there has been very slight 

 movement during the Tertiary, and that the present limits of the conti- 

 nental shelf represent probably the extreme extension of the land in the 

 Pleistocene. Dall has shown the evidence very clearly in the case of 

 Florida. Apparently the conditions in Yucatan are partly similar, but 

 Vaughan has shown that its tectonic relations to the Antillean ridges are 

 more favorable to a former union. 



