STRATIFIED SAND AND GRAVEL 519 



If an}' correlation by fossils were possible, it would seem, on the basis 

 of these comparisons, that the clays found beneath the Winthrop drum- 

 lins and those incorporated in the dmmlins of Boston harbor were of 

 different age from the clays at Lynn, Danvers, and at other points north 

 of Boston, and that those at Lynn and Danvers might be the same as 

 those on the coast of Maine. Pacl^ard* describes the geographic range 

 of the various species, and states that the difference between the fauna 

 north and south of cape Ann is due to the difference in climate at the 

 time the claj's were deposited, and assumes that the marine clays are all 

 of the same age. On the basis of stratigraphic evidence this does not 

 seem to be true. Moreover, the change in species is not at cape Ann, l)ut 

 between Boston and Lynn, and between these two localities there was no 

 barrier nor other geographic feature sufficient to separate a temperate 

 from an arctic fauna. Hence the conclusion that the clays north and 

 south of Lynn are of different age seems well substantiated, the former, 

 as will be shown in a subsequent section, being younger than the drumlin 

 till, while the latter are older. 



The data do not enable us to distinguish l)etween the two clays on the 

 Maine coast, nor do they throw any light on the age of the Cambridge 

 and Eevere clays, as these latter do not contain fossils. 



STRATIFIED 8.1ND AND GRAVEL 



Although clay of Gardiner age north of Boston is exposed only at 

 Winthrop, one case has been observed where stratified sand and gravel 

 underlie a drumlin. This Avas at Little Boars head, N"ew Hampshire, 

 which is a drumlin-like hill, on the seaward face of Avhich the following 

 section was seen : 



Section at Little Bours Head, New Hampshire 



Fppt 



C. Sandy find bonldery till, Wisconsin 1 to 8 



B. Hard vertical till, clayey, bouldery. Montank 10 to 20 



A. Patch of horizontally stratified sand and gravel 100 feet long. .... G 



This may simply be a case of local interstratification of gravel in a 



drumlin, or the deposit may be analogous to tlie Herod gravel which 



overlies the Gardiner clay and underlies the Montauk drift on Long 



island. Considering the size and horizontal stratification of the deposit, 



, the latter supposition is more probably the true one. 



* A. S. Packard : Observations on the glacial pbenomena of Labrador and Maine. 

 Mem. Boston Soc. Nat. Hist., vol. 1, 1865, pp. 210-.303. 



