26 FLORA OF SOUTHERN NEW YORK AND NEW ENGLAND. 



hardening, is a question which has not as yet been satisfactorily answered. The coin- 

 cidence of its abundance in connection with the moraine, or in Cretaceous beds more 

 or less disturbed bj' glacial action, is significant, especially when compared with the 

 relative rarity of similar material in equivalent undisturbed beds ; and the fact that 

 masses and fragments of clay may be found which show every gradation between 

 the plastic condition and that of hard ferruginous shale or sohd concretions would 

 seem to indicate that these conditions have been brought about, at least in some 

 uistances,fi'om the oxidation of iron contained in the clay and in others from the accu- 

 mulation of layers of limonite around the exterior of clay fragments after these were 

 torn from the parent mass. Even where the sliales or concretions are in place in 

 the clays, as at Glen Cove and Gay Head, the clays themselves must be regarded as 

 merely part of the moraine, representing portions of the Cretaceous beds which were 

 eroded and transported bodily or else shoved forward or squeezed upward from their 

 original positions by the advancing ice front and not as undisturbed strata in place. 



This conspicuous feature, therefore, consisting of hardened fragments and concre- 

 tions, while it must be recognized as more or less characteristic where it occurs so 

 conspicuously, may not always be an original phase of the deposit, but maj'' in cer- 

 taua exposures be due merely to the accident of their location within the area of 

 glacial disturbance. 



Examples of erosion, transportation, and deformation of the Cretaceous deposits 

 by ice action are conspicuous throughout almost the entire morainal area from 

 Marthas Vineyard to Staten Island. In only two limited locahties are the jshenom- 

 ena wanting. One of these is the northern or Orient Point branch of the moraine on 

 Long Island ; the other is where the moraine rests upon the serpentine hills of Staten 

 Island. In the last-named locality the absence of Cretaceous material is due to the 

 fact that the Cretaceous deposits did not extend north of these hills, while at Orient 

 Point its absence is probably to be explained on the theory that this point represents 

 a second or more recent morainal deposit, and that all of the Cretaceous material had 

 been^previously eroded and included in the older or Montauk Point branch. 



On the several islands the exact conditions under wliich the fossil plants occur 

 vary to some extent, and variations in conditions may be noted between certain 

 locahties on the same island. Within our region the farthest north that any Creta- 

 ceous material has been positively identified is on Naushon, the most eastern of the 

 Elizabeth Islands, where there is a limited amount of plastic clay and some of the 

 characteristic ferruginous concretions containing hgnite, all included in the moraine. 

 The farthest east that any similar material has been reported is Chappaquiddick, 

 at the southeastern extremity of Marthas Vineyard, where characteristic species of 

 Cretaceous plants occur in the ferruginous shaly fragments which form a large part 

 of the reassorted drift material of that locality. Thus far no positive evidence has 

 been obtained of the presence of a Cretaceous flora farther to the north, on Cape Cod, 

 or farther to the east, on Nantucket, and definite proof that any of the Cretaceous 

 formations were represented in those localities at all has not been recorded, so far as 

 I am aware. 



At Nashaquitsa, on Marthas Vineyard, the plant remains occur in clay nodules, 

 embedded in the variegated clays of the chff, which apparently form the outcropping 

 edge of a basin or trough of which the Gay Head section, is part of the opposite rim. 



