2 
Attention was first called to this forma- 
tion by Prof, iritciicock in 1823, who appears to be the 
onlv American p:eolofvist v/ho has exaxiined them person- 
ally. He compared the l)eds at Gay Head to the plas- 
tic and London clays of Aluiri Bay in the Isle of Wight, 
to which, lithologically , they "bear a striking resem- 
hlanca, consisting in both cases of variously and bright- 
ly colored clays and sands with lignite, all incoherent 
and highly inclined. Yarious opinions, however, have 
heen put forth ae to the relative aj^e of the Llartha's 
Vineyard strata, which were assigned oy Prof* Hitcii-' 
cock, at a time when the tertiary formations of the 
United States were less known, to the eocene period, 
while Dr# Morton suT)posed them to be in part only ter- 
tiary, and that they rested on green-sand of the cre- 
taceous period. 
The section at Gay Plead is continuous for 
four fifths of a mile; the hads dip to the northeast 
generally at an angle of from thirty five to fifty de- 
grees, though. in some places at seventy degrees* The 
clavs Dredominate over the sands. In one place IIr# Lyell 
found a great fold in • the "beds, in wliich the saiae osseous 
conglomerate and associated "beds o% white sand, on the 
whole fiftv feet thick, were so hent as to have twice 
