Art. XI I, --On the Tertiary Strata of the Islands of 
I^artha's Vineyard in Ilassacliusetts: "oy Charles 
The most nort^^arn limit to wliicli the tertiary, strata 
"bordering the Atlantic have heen traced in the United 
Statee, is in LlasBachusettB ^ in Jlartlia^s Vineyard ^lat . ■ 
41^ 20* north, an island a.bout twentv rriiies in len^-^-tli 
from east to west, and ahout ten from north to south, 
and rising to the height of betv/een t\yo and three hun- 
dred feet ahovQ the sea. The tertiary strata of this 
island are, for the most jjart, deeply huried "beneath a 
mass of drift, in v/hich lie hu^e erratic olocks of gran- 
ite and other rocks, v/hich appear to ha.va come from the 
north, prohahly from the mountains of ITew Hampshire. 
The tertiary strata consist of \.'">ite and green sands, 
a conglomerate, white, hlue , :/ellov;, and hlood-rsd clays, 
and hlack layers of lignite, all inclined at a higli an- 
gle to the northeast, and in some of their curves auite 
t . ' ■ 
vertical. They are finely exposed near Chilmark on the 
southwest side of the island, and in' the promontory of 
Gay Head at its southwestern extremity, where there is 
a vertical section of more than tv/o hundred fact in 
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^rrom the roceedings of the London Geol .Soc . Vol . IV 
IIo . 92 
