Revieics — Dr. Spencer — The AntiUean Continent. 175 



" In Cuba, Jamaica, and San Domingo, resting upon the upturned 

 edges and denuded surfaces of Miocene and earlier formations, there 

 is a deposit of soft earthy white or creamy limestone, made out of 

 the mechanical residue of older limestones, with some small masses 

 of corals and shells. All the observed species in Cuba are the same 

 as the living ones. To this formation the writer has given the name 

 of the Matanzas series. Owing to the modern facies of the organic 

 remains Salterain has included it in the post-Pliocene, but states 

 that it may be Pliocene." Dr. Spencer correlates this with certain 

 deposits in Florida, Yucatan, and elsewhere, and infers a great 

 subsidence and drowning of the Pliocene land at this time. 



But the present position of the Matanzas limestone and the deep 

 valleys which have been cut through it indicate a subsequent 

 upheaval of the whole region equal to that of the Pliocene elevation. 

 This was a second continental period, but it seems as if the Atlas of 

 the Antilles soon became tired of holding up the land at such a height, 

 and so let it down again for a time in the later Pleistocene to receive 

 another set of marine deposits (Zapata and Columbian). Finally 

 there were other movements of less extent, by which the present 

 arrangement of sea and land has been produced. With respect to 

 the formation of the Central American barrier, Dr. Spencer thinks 

 that it was accomplished entirely within Pleistocene time. Islands 

 doubtless existed there from early Tertiary times, but the deforma- 

 tion which converted them into a ridge and the Antillean Seas into 

 basins did not begin till late Pliocene time, and the Pacific waters 

 were not finally shut out till the very latest, or post-Zapata, upheaval 

 of the land. 



Dr. Spencer has evidently thrown all his well-known energy and 

 acumen into this investigation, and may be congratulated on the 

 work he has accomplished in connection with it. Many of his 

 conclusions are doubtless based on substantial evidence and ascer- 

 tained facts, but the wonderful series of earth-movements which he 

 postulates depends on correct correlation of deposits in different 

 parts of the area, and in this matter there is at present room for 

 difference of opinion. Future researches may possibly necessitate 

 some modifications in the later part of his history, and he will have 

 to prove that the latest deformation did not include a north and 

 south upheaval of the Windward Eidge as well as a warping up of 

 Central America, for this seems to me very possible. However this 

 may turn out it would not materially affect the bi'oader generaliza- 

 tions now made, as to the former continental extension, and as to 

 the late date of the Central American barrier. 



Dr. Spencer is fully sensible of the startling nature of his 

 conclusions, but so far as the magnitude of the vertical movements 

 are concerned they will not astonish anyone who has accepted the 

 results of recent work in Barbados. 



A. J. Jukes-Bkowne. 



