Conglomerates, ete., of Sauk County. Wisconsin. 447 
This section then represents an old Azoic reef of tilted rock, 
running east and west, washed upon either side by the waves 
of the Potsdam sea. On the south the action appears to have 
been gentler than on the north, for while at the south the 
quartzite has been triturated toa fine sand, containing, to be 
sure, larger or smaller pieces of quartzite, well rounded, the 
northern shore must have been exposed to the breakers which 
washed out the fine sand and left pebbles of a uniform size. 
It may be that within the circle of these islands was a sheltered 
bay. Mr. Chamberlain has observed ata little distance back 
from the edge of the cliff, sandstone again covering the con- 
glomerate and, in fact, the entire length of the quartzite, indi- 
cating a subsequent subsidence of the entire reef below the 
Water. 
At the point marked (5) on the map is a limestone quarry. 
It is horizontally bedded. All points of junction with the 
underlying rock are concealed, but it is plainly, at least, 100 
feet below the Potsdam sandstone in place. Whether it is a local 
deposit in the Potsdam sandstone or is the Lower Magnesian 
limestone, I have not yet determined. The latter supposition 
requires an enormous erosion between the putting down of the 
Potsdam sandstone and the Lower Magnesian liméstone. A 
number of fossils were secured, several cephalic shields of a 
trilobite, a Plewrotomaria? and others still more indefinitely 
own. 
Another feature of interest in this region is the evidence of 
glacial action aside from the drift. At the point (3) on the 
the rock. It was entirely smoothed and covered with glacial 
Striz. Their direction was N. 66° E. On the surface of the 
limestone previously mentioned, the polishing is even more 
perfect, Reed the strix have the same direction. The only way 
I can explain this deflection from the usual direction is, that it 
was caused by the trend of the ridges. At the Glacial epoch, 
me erosion of the Baraboo Valley must have been as great as 
a 
that I especially mentioned to a agli * * showing probable 
$s 0 | 
re) ' 
bluffs, within the glacial limit, which is east of the ‘ Lake of 
ne Bluffs.’ There i i 
piled upon the top of the bluffs.” 
Beloit, Wisconsin, Feb, 14, 1873. 
