252 A. S. PACKAED, Jr., ON THE GLACIAL PHENOMENA 



and northeastern Maine was sudden, and no more distinctly marked than at the present 

 day ; — any light thrown upon the characters and distribution of this formation south of 

 Cape Cod possesses the liveliest interest. 



We have been led to believe that in the drift period, the present course of both the 

 arctic current and the Gulf Stream existed at a very early period of that epoch from Lab- 

 rador to Florida, and the abundant palaeontological evidence now before us proves this to 

 have been the case. It is most probable that during the period of glaciers in the northern 

 parts of the continent, the growth of the coral reefs of Florida and the West Indies was 

 not interrupted ; and that a sub-tropical fauna existed in South Carolina, contemporane- 

 ously with the sub-arctic fauna peopling the seas of the southwestern coast of Maine, and 

 the more purely arctic, glacial fauna, inhabiting the waters of Labrador and the Gulf of 

 St. Lawrence. 



Messrs. Desor and Cabot J have happily filled up the gap in our knowledge of the beds 

 on the coast of New England lying just south of Cape Cocl, in a paper which we were not 

 aware had been published until most of this article had been prepared for the press, and 

 subsequent to the publication of an abstract of the present article in the American Jour- 

 nal of Science and Arts, New Haven, January, 1866. 



The authors give a section of the drift beds, seventy-two feet in thickness, at Sancati 

 Head, forming the eastern extremity of the island of Nantucket, resting upon twenty feet 

 of a brown clay which is referred to the Miocene Tertiary, which is considered as probably 

 contemporaneous with a similar clay underlying the drift at Truro, Cape Cod, and also with 

 the brown sandy clay at Martha's Vineyard, proved by Sir Charles Lyell to be miocene. 

 Resting unconformably upon the brown clay are beds presenting the following section in 

 the ascending order. (1.) a bed of gravel, — two feet; (2.) homogeneous white sand, — 

 four feet; (3.) tough clay, very similar in its aspect to the plastic clay near Paris, except 

 that it contains a great many nodules of ferruginous sand, — one foot; (4.) "an oyster bank 

 one foot thick, intermixed and covered by (5.) large masses of Serpula ; which are like the 

 oysters, in their natural position," with many other shells, — four feet; (6.) a stratum of 

 worn shells which " bear evident traces of exposure, the valves of the bivalves being gen- 

 erally isolated, and the Balanus disintegrated and more or less worn, — two feet." "Above 

 this stratum of loose shells there is found a series of layers of sand and gravel, with a 

 thickness of nearly fifty feet, in which every variety of materials may be seen, from the 

 finest sand to the coarsest gravel." These beds dipped westward from five to fifteen de- 

 grees, the beds becoming less inclined from below upward. 



We quote at length the conclusions of the authors, as the paper is not generally acces- 

 sible to American students : — 



" Concerning the drift overlying the tertiary clay at Sancati, it is obvious from the regu- 

 larity of the strata, and from the very perfect state of preservation of the shells imbedded 

 in it, that it has not undergone any violent disturbance since their deposition. The spe- 

 cies collected by us in the above-mentioned oyster bank are the following : — 



Venus mcrcenaria, plenty. Solen ensis, abundant, but very brittle. 



My a arenaria, plenty. Astarlc cartanca, rather rare. 



Ostrea borealis, a bed several feet thick. Cardita borealls, rare. 



Area transversa, very abundant. Cumingia tellinoides, rather rare. 



1 " On the Tertiary and more recent Deposits in tlie Island of Nantucket." By E. Desor and E. C. Cabot. Quart. 

 Journ. Geol. Soc. London, V. p. 340, Feb. 184 9. 



