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SCIENCE. 



NEW YORK ACADEMY OF SCIENCES. 



November 7, 1881. 



Regular Business Meeting. 



The President, Dr. J. S. Newberry, in the Chair. 

 Twenty-nine persons present. 

 A paper by Prof. P. T. Cleve, University of Upsala, 

 Sweden, was read, by Prof. D. S. Martin, entitled 



Outlines of the Geology of the Northeast- 

 ern West India Islands. 



(Abstract.) 



Prof. Cleve's paper contained a resume of his obser- 

 vations made during 1868-9, > n ar) d around the Virgin 

 Islands, and published in tne Swedish language in the 

 Trans. R. Acad. Sci. of Stockholm, in 1871. He re- 

 gards the whole group as of Cretaceous and Tertiary 

 age, with the exception of Anegada, which, like the 

 Bahamas, is post-pliocene. 



The strike of the rocks, and the trend of the entire 

 group, are approximately east and west. The rocks are 

 various, largely eruptive and metamorphic. Of these, 

 Prof. Cleve discussed somewhat fully the character and 

 distribution of the following kinds: — 1, Dionte; 2, Fel- 

 site ; 3, " Blue-beach " (a peculiar volcanic breccia, 

 locally so-called); 4, Diabase. 



All these rocks have great thickness, and indicate long- 

 continued volcanic activity. As in modern lavas, they 

 present two types, basic and acidic. 



Metamorphic slates are next described ; and then a 

 partly metamorphic limestone, occasionally with recog- 

 nizable fossils, sufficient to fix the age as certainly Cre- 

 taceous. 



Santa Cruz Island is then described, and referred to the 

 same series as the Virgin group. All these islands thus 

 indicate, by their east and west strike, and the great up- 

 turning ot their rocks, that they were formed by a north 

 and south pressure, forcing the Cretaceous and asso- 

 ciated volcanic beds into a great line of anticlinal and 

 synclinal folds. This period seems to have been about 

 that of the white chalk ; but the force continued to act 

 during the succeeding Eocene time, though with dimin- 

 ishing intensity, as is shown by the less inclination of the 

 Eocene beds. The Miocene strata are little disturbed, 

 and the force would therefore seem to have spent itself 

 by that period. 



Prof. Cleve then refers briefly to the occurrence of 

 similar metamorphic and volcanic rocks in the interior of 

 the Great Antilles, and regards the entire series as hav- 

 ing been formed by the same general movement of 

 Cretaceous folding, the Virgin Islands forming the east- 

 ern extension of the line of elevation. 



The Eocene strata are then taken up and discussed, as 

 they occur in the islands of St. Martin and St. Barthol- 

 omew, just east of the Virgin group. Professor Cleve 

 regards these islands as wholly of Eocene age, claiming 

 that the eruptive rocks of which they mainly consist, are 

 interslratified with the limestones, which contain fossils 

 of the age of the Calcaire Grossier, of the Eocene of 

 Paris. He then traces the occurrence of Eocene strata 

 in Antigua, Guadaloupe, parts of Trinidad, and largely 

 in Jamaica ; and re-affirms his conclusion that the move- 

 ment which raised the Great Antilles and the Virgin 

 islands continued during the early Tertiary, though with 

 lessening force. 



The Miocene formation is then considered. It forms 

 the small island of Anguilla, and occurs on several of the 

 islands, south to Trinidad ; but has immense develop- 

 ment in the Great Antilles. It is chiefly a limestone 

 series, is generally little altered from a horizontal posi- 

 tion, and at times may be seen resting uncomtormably on 

 the Eocene. By this time, evidently, the disturbing 

 movements had ceased to make themselves felt. 



The later Tertiary rocks, Pliocene and Post-pliocene, : 



have not been very clearly marked off from each other or 

 from the Miocene. But to the Post-pliocene period are 

 referred the Bahamas, Anegada, and the remarkable 

 series of volcanic outbreaks that characterize the islands 

 of Saba, St. Eustatius, St. Kitts, Nevis, Monserrat, 

 Guadaloupe, &c. On 'St. Kitts, Prof. Cleve describes a 

 limestone with over forty species of fossil shells, all but 

 one of which are identified with living j pedes of the 

 Caribbean sea. The same is true of Anegada. 



The elevation of the Miocene strata of the Great 

 Antilles took place apparently by a "continental " up- 

 lift, whereby large areas of marine deposit were raised 

 without folding or disturbance. Professor Cleve suggests 

 that this movement may have been accompanied by a 

 sinking of part ot the sea-bottom in the Caribljean region 

 to the south-east, and that on the limit between the 

 areas of rise and of depression, fissures and faults may 

 have occurred, through which these volcanic outbreaks 

 of the Leeward islands found exit, in the Post-pliocene 

 time. 



discussion. 



Mr. A. A. Julien confirmed the accuracy of these 

 petrographical distinctions of the rocks of the Lesser 

 Antilles, from the results of observation during a resi- 

 dence of four years on Sombrero and vicinity. The 

 island ot St. Eustatia consists mainly of volcanic ashes in a 

 thick tabular and horizontal stratum with vertical faces 

 along its coast. This is flanked on the south end by a 

 volcanic cone with extinct crater, of which the bottom is 

 occupied by a plantain plantation, but the sides are bare, 

 and consist of a dark basaltic rock ; and on the north 

 end by two lower cones, not visited but probably vol- 

 canic. On the island of Saba the rock is light colored, 

 rich in crystals ot sanidine, and apparently a trachyte, 

 constituting a remarkably sharp volcanic cone, with its 

 sides deeply furrowed from top to bottom by eroded 

 ravines ; certain depressions upon the summit, resem- 

 bling craters, present in some localities sulphur deposits 

 which have been found of commercial importance. 



However, the conclusion of Prof. Cleve, as to the 

 recent age and eruptive character of most of the crystal- 

 line rocks ot this region, appeared surprising in view of 

 their metamorphic associates, and of their similarity to 

 those of the Archaean areas identified by Hartt in Brazil. 

 It was a question whether a nucleus ot Archaean, or, at 

 latest, metamorphic pre-Silurian rocks, in general highly 

 tilted, does not form the axis of such islands as St. Mar- 

 tin, St. Barts, etc. 



Prof. D. S. Martin questioned whether a correspond- 

 ing movement of disturbance should not be also found 

 in the Cretaceous strata of a region no farther removed 

 than that of the vicinity of our own Gulf coast. 



Dr. J. S. Newberry remarked that the importance of 

 the subject of the age and origin of these crystalline 

 rocks still demanded their re-examination and a review of 

 Prof. Cleve's conclusions by some worker of experience 

 in this peculiar field. One of the most interesting topo- 

 graphical features on this continent consisted in the line or 

 axis of elevation marked by the Windward Islands, separat- 

 ing the deep basin of the Gulf of Mexico on the one side 

 from the abyss of the Atlantic Ocean on the other. It pre- 

 sents a prolongation and connection of the mountain 

 chains which run along the eastern border of the North 

 and South American continents, in a course imperfectly 

 parallel to that on the western border of these con- 

 tinents, with the gulf lying enclosed between these two 

 great ranges. This axis has been the scene of violent 

 volcanic action and has been supposed to mark the 

 place of that mythical area of sunken land, styled 

 Atlantis by the ancients. The tradition long current, 

 recorded by Herodotus and others, points to a densely 

 populated land west of Europe, covered with cities, and 

 threatening the civilization ol the Eastern hemisphere, 

 which was punished by the gods by being sunk beneath 

 • the sea. According to the recent observations of an 



