224 AMADEUS W. GRABAU 
from 115 to 215 feet of strata beneath the Black River, and resting 
disconformably upon the Lower Beekmantown (Theresa formation), 
which, with its basal sandstone (called Potsdam by Cushing), has a 
maximum thickness of 140 feet. Cushing restricts the term Lowville 
to the upper 75 to 85 feet of pre-Black River strata, separating the 
lower part, on paleontologic grounds, as the Pamelia limestone. 
At Lowville and elsewhere this series overlaps the Beekmantown, 
resting with a basal sandstone upon the crystallines. The Pamelia 
fauna is an Upper Stones River fauna, according to Ulrich, while 
the fauna of the Lowville is compared with that of the Upper Chazy.* 
In the Canadian region, only Upper Chazy (Lowville and pos- 
sibly the Pamelia equivalent) is present. In a number of localities 
it rests directly upon the pre-Cambrics, generally with a basal sand- 
stone (St. Mary’s sandstone). In some cases, however, lower beds 
(Beekmantown, with basal sands) have been reported. In Min- 
nesota and Wisconsin the Upper Chazy is called Stones River, though 
it represents only the upper part of the Stones River formation of 
Safford’s Tennessee section where the thickness is 360 feet. The 
Minnesota beds are 32 feet thick and are probably the exact equiva- 
lent of the Lowville of New York, though the fauna is stated to be 
more like that of the Pamelia. The relation of these beds to the 
underlying St. Peter sandstone is significant, since the contact is per 
fectly conformable and gradational. Moreover, Stones River fossils 
(Hormotoma gracilis, Lophospira perangulata, etc.) are found in 
some of the upper beds of the St. Peter, showing that with the 
advent of the Chazy sea, the sand dunes of the St. Peter desert were 
incorporated as basal sands in the overlying formation. ‘This meant, 
of course, a slight reworking of the sands by the encroaching sea. 
That this reworking did not reach to the bottom of the St. Peter, at 
least not in all cases, is shown by the persistence of the folds and faults 
in the lower beds, whereas they are absent in the upper (see Fig. 4). 
A comparison of sections shows that in general lower beds of Chazy 
age appear progressively above the St. Peter as we proceed southward 
and eastward. The relationship of these beds to the St. Peter 
has not been discussed in detail, but it is certain that in some localities, 
at least, the gradation observed in Minnesota obtains. The relation- 
t See Cushing, loc. cit. 
