356 COPPER-BEARING ROCKS OF LAKE SUPERIOR, 
there with a slight northwesterly dip (2°-5°), but more often with a south- 
easterly one. These conditions obtain for a mile or more down the stream. 
Mr. Wadsworth has also described the exposures on the Douglas Hough- 
ton River, and correctly, so far as showing—which he was the first to do— 
that the conglomerate for some distance below the falls does not belong 
with the Eastern Sandstone, but is really interbedded between diabases of 
the Keweenaw Series. When he represents, however, the sandstone still 
farther down stream as passing beneath the last Keweenawan diabase, he 
bridges in his imagination a covered gap of several hundred paces; beyond 
which, to the eastward, the sandstone lies flat, or inclines varyingly and in- 
differently slightly to the northwest, southwest, or southeast, not showing 
any sign of a persistent and gradually decreasing northwestern dip. Were 
this ravine the only place where the Eastern Sandstone could be seen in 
proximity to the north-dipping Keweenawan beds, and were there not 
other considerations rendering such a conclusion untenable, the idea that 
Mr. Wadsworth has advanced might perhaps suggest itself as a possibility, 
although so far as the exposures kere are concerned it could be nothing 
more. There would remain even then as looking the other way a marked 
lithological difference between the intercalated sandstone and that farther 
down the stream; the latter being a much more purely quartzose rock, 
while at the same time containing pebbles of the porphyry whose detritus 
composes the usual interbedded sandstones of the trappean series. 
About a mile south from the head of the Douglas Houghton ravine, 
on the line of the Torch Lake Railroad, is a large quarry in the Eastern 
Sandstone. The sandstone is disposed horizontally in heavy massive 
layers. It is nearly white and almost wholly composed of rolled quartz 
grains. It also contains here and there grains of feldspar, somewhat 
altered, but on the whole singularly fresh for such a rock, some particles 
showing the twin lamellation very beautifully. A very minute quantity of 
a brownish cement is present, and in each thin section may be seen two 
or three grains worn from some of the fine-grained diabases of the Kewee- 
naw Series. Not a trace is to be seen of anything like the fragments of 
porphyry matrix, so abundant in the _Keweenawan sandstones; nor was I 
able to discover any satisfactory indications that the quartz-grains are the 
