Drift in Minneapolis, Minn. — Upham. 277 
and easily eroded St. Peter sandstone. These formations, with 
some part of the overlying- Trenton shales, are the bed rocks 
next beneath the drift on all the city area. Their only natural 
exposures, however, are in the Mississippi gorge from the 
southeast corner of the city to St. Anthony's falls, and for a 
short distance above the falls; in the short Minnehaha gorge; 
on Shingle creek (the St. Peter sandstone), a (juarter of a mile 
from its mouth; and beside Washington avenue, within a mile 
south of this creek (quarries of the Trenton limestone). Prof. 
N. H. Winchell, the state geologist, has fully described these 
formations in his reports of Hennepin county.* 
Besides several shallow artesian wells, obtaining water 
from layers of the drift, along the northern base of the uneven 
esker ridge which includes Lowry hill, deep borings for arte- 
sian water have been made at several places in Minneapolis, 
to a maximimi depth, in Lakewood cemetery, of 2,150 feet 
from the surface, pentratiug 1,250 feet beneath the level of 
the sea. In the records of these deep wells, with aid from 
studies by Prof. Winchellfand Prof. C. W. Hall,'|; I recognize 
the following series of Lower Silurian and Cambrian forma- 
tions, in their descending stratigraphic order: 
Feet 
Trenton limestone, about 30 
St. Peter sandstone 164-168 
Shakopee limestone, doiomitic 101-133 
Jordan sandstone g6-ii6 
St. Lawrence limestone and shales I28-I()0 
Dresbach sandstone 82-86 
St. Croix lower shales and limestone 155-179 
St. Croix lower sandstone 188-217 
Potsdam red shales and sandstone 1027 
At the base of the lowest of these formations, Hall states 
*Geol. and Nat. Hist. Survey of Minnesota, Fifth Annual Report, 
for 1876, pp. 162-219, with two maps and a section; Final Report, vol. 
ii, 1888, pp. 264-344, with a map of the county, and 15 plates (maps and 
views) illustratintic the recession of the falls of St. Anthony, and seven 
sections figured in the text. 
tI\eports cited; also. Tenth Ann. Re))., for 1881, i)p. 211-217; Thir- 
teenth Ann, Rep., for 1884, i)iJ. 50-54; and Fourteenth Ann. Rep., for 18S5, 
pp. II, 12. 
Jlkilletinof the Minnesota Academy of Natural Sciences, vol. iii,]))!. 
128-143, with a plate (twelve sections from well records, and a general 
section from St. Cloud to the southeast corner of Minnesota), read Nov. 
3, 1885, published in 1889. 
