a 
PUMPELLY ON THE EASTERN SANDSTONE. 363 
part of the Eastern Sandstone. However, on Béte Grise Bay, where there 
can be no possibility of doubt, the Eastern Sandstone at the contact con- 
tains layers in which diabase and amygdaloid pebbles are abundant, along 
with others of red felsite and quartziferous and granitic porphyries. In 
advancing this view Pumpelly was simply attempting to carry to demon- 
stration what had before been suspected by Logan and other earlier geolo- 
gists. In abandoning the idea of a fault along the south side of Keweenaw 
Point he saw that it would be necessary to account for the disappearance 
of the seven miles in thickness of rocks constituting Keweenaw Point—of 
which fully two miles are red sandstone and conglomerate of unquestioned 
sedimentary origin—in the few miles intervening between the point and the 
southern end of Keweenaw Bay, where the Eastern Sandstone lies directly 
upon the Huronian slates. This he did by supposing an enormous Pre- 
Cambrian erosion, thus making the break between the Keweenaw and 
Eastern Sandstone an immensely great one. 
Recently Mr. M. E. Wadsworth has maintained a view, previously sug- 
gested by Credner,’ namely, that the Eastern Sandstone passes underneath 
the entire copper series, forming its lowermost member, or lowermost mem- 
ber in sight. This conclusion he rests on observations made on the Douglas 
Houghton and Hungarian rivers. I have already shown that the exposures 
on the Hungarian River will not admit of any such explanation, while those 
on the Douglas Houghton, taken alone, could only be thus explained by 
imagining an appropriate structure within an interval where there are no 
exposures. But there is no necessity of going to these streams to prove the 
untenableness of Wadsworth’s peculiar position, although he considers that 
it “settles the long-disputed question of the relative age of the traps and 
b] 
Eastern Sandstone of Lake Superior.” The large exposures of south-dipping 
sandstone on Béte Grise Bay, at the contact with the Keweenawan melaphyr, 
and the similar exposures on the south side of the Trap Range in the vicinity 
of the Ontonagon River, are enough to disprove absolutely any such struc- 
tural theory. In Mr. Wadsworth’s view the Eastern Sandstone antedates 
all the Keweenawan eruptions, and yet it holds frequent pebbles of both 
acid and basic Keweenawan eruptives, whose characters are so pronounced 
1Elemente der Geologie, 4th edition, 1878, p. 416. 
