370 The American Geologist. Docember, 1897 
dolomite, 30 feet, Jordan sandstone, 75 feet, St. Lawrence dol- 
omites and shales, 40 feet. At this place the Oneota and Jor- 
dan formations are rather sharplj^ separated, as are likewise 
the Jordan and St. Lawrence; but the lower limit of the St. 
Lawrence is not prominently marked. 
Below the St. Lawrence formation a series of more or less 
clearly defined beds of sandstone, shales, greensands, calcare- 
ous shales, pyritiferous shales and conglomerates has been in- 
cluded by geologists in the terms, — Lower sandstone,* Pots- 
dam sandstone,! St. Croix sandstone,]; Basal sandstone, § 
and Dresbach and Hinckley sandstones, || without subdivision. 
The fauna, which seems largely confined to the lowest shales, 
was considered too meagre for a satisfactory correlation of 
the formation, and a discouragementat the outset to any suc- 
cessful subdivision. 
Additional Data. Explorations of the writer have brought 
to light several facts which bear directly upon the question of 
correlation and subdivision of the lower sedimentary rocks of 
this district. They are the following: 
The existence of a well-marked sandstone conglomerate ha."? been 
determined: and St. Lawrence shales have been found to occur in Sec. 
1. T. 33N.,R. 19 W. 
The persistence of certain lithologic characters have been shown. 
The discovery has been made of an extensive fauna in the marginal 
conglomerates. 
The Sandstone Conglomerate. Along the wagon road 
through the N. E. i, N. E. i. Sec. 1, T. 33 N., R. 19 W., there 
is exposed, to a limited extent, an interesting conglomerate, of 
which specimens are readily obtained. The significance of 
the occurrence lies in the fact that the worn pebbles of this 
conglomerate are of sandstone, which are enclosed in a matrix 
of sandstone. The pebbles are little more compact and resist- 
ant than the^matrix sand itself, are perfectly worn and range 
*Owen: Geol. Survey of Wis., Iowa and Minn., 1852. 
tChamberlin: Geol. of Wisconsin, vol. i, 1883, p. 123. 
Hall and Sardeson: Bull. Geol. Soc. of America, vol. 3, 1892, pp. 
331-368. 
JUpham: Geol. and Nat. Hist. Survey of Minn., Final Report, vol. ii, 
1888, p. 407. Winchell: Final Rep., vol. i, 1884, p. 257. 
§Norton: Iowa Geol. Survey, vol. vi, 1897, p. 140. 
llWinchell: Final Rep.,' vol. ii, 1888, p. xxii, and 21st An. Rep. Geol. 
and Nat. Hist. Survey of Minn., 1892, chart, p. 5. 
