14 



Owing to the lateness of the hour, the botanical paper of the 

 evening, by Mr. Hollick, on the "Relation between Geological 

 Formations and the Distribution of Plants," was merely read by title 

 and handed to the Editor for publication in the Bulletin. 



6. Relations between Geological Formations and the Distribu- 

 tion of Plants. — The notes, from which this paper was compiled were 

 taken durmg the past season on Staten Island and are, therefore, very 

 restricted and local in their nature; but even within such narrow 

 limits, the effect which the geological formation seems to have on its 

 accompanying flop is so marked, that it seems of vast importance, 

 alike to the practical botanist in his collecting tours, and as a field of 

 speculation for the theorist. 



We have, on Staten Island, two well marked geological features 

 the Drift, which covers about two-thirds of the entire Island, 

 nearly all the northern part and extending as far south as Princes 

 Bay, and the Cretaceous, which occupies the remaining small area in 

 the southern and western part. This latter is a continuation of the 

 New Jersey clay beds. 



The geological line of separation between the two formations is 

 not always very distinct, but the limits of the different species of 

 plants mark it in unmistakeable characters. The two floras are 

 remarkably distinct. That one belonging to the Cretaceous is well 

 represented by Arctostaphylos Uva-ursi, Aster concolor, Finns inop, 

 Quercus Fhellos, Quercus nigra, Lycopodium inundaium, var. Bigelovii^ 

 and many more of the Pine Barren plants. Thus far I have never 

 foundone of these species to have crossed the line of the Drift, but 

 in their stead will be found Pinus rigida, Quercus alba, Quercus rubra, 

 etc., and the majority of those plants which grow in the vicinity of 

 New York Island, and up the Hudson. 



Those plants which belong to the Drift seem to adapt themselves 

 more readily to the Cretaceous than "vice versa," for while we find 

 Quercus alba and Pinus rigida growing in Cretaceous clays and 

 sands, the Quercus Phellos and Pinus inops have never been seen out 

 of their natural geological location. The same may also be said of 

 the more northern species of Aster, which occur quite plentifully with 

 Aster concolor, but this latter will not spread beyond the Cretaceous 

 It would be interesting to know if these facts hold good in other 

 localities. It almost seems as if the Drift flora were gaining on the 

 Cretaceous and gradually crowding it off the Island. 



A curious and interesting case of restricted locality, due appar- 

 ently to geological causes, is seen in Clematis ochroleuca, which only 

 grows on the dry hills of magnesian rocks which form the main ridge 

 of the Island and in the vicinity of the Limonite ore deposits. — It is 

 accompanied by Cerastium tf^/tf«^//"^//i^»/, which likewise seems equally 

 restricted. Do these same conditions prevail in other localities where 

 these comparatively rare plants occur ?— In an isolated hammock of 

 soapstone and iron ore, fully three-fourths of a mile away from the 

 ridge, and having no intermediate connections. Clematis ochroleuca 

 was found. Probably by others, who have had a wider area for 

 research, many more instances of a similar nature may have been 



