274 The Amcncan Geologist. May, i9f)o 
Description of the Area. 
The city of Minneapolis, mapped on plate VI, occupies 
an area of 53 square miles, very nearly, in the east part of 
Hennepin county. This area, reaching ten miles from north to 
south, with a maximum width of a little more than six miles, 
is intersected by the Mississippi river, and includes about 12 
square miles on the cast side, which is the only part of Henne- 
pin county east of the river. On the southeast, for about three 
miles, this river is the city boundary; and above ^Minneapolis 
it is the county boundary. 
Near the center of the city are the falls of St. Anthony, 
which, before the building of dams for the use of water power, 
were the only cataract or perpendicular plunge of the Mississ- 
ippi river in its entire course. The precipitous fall was about 
16 feet, and within the next mile there is a descent of 60 feet by 
rapids. From the still water above the dam to the southeast 
corner of the city area, the river falls 100 feet, from 800 to 700 
feet, approximately, above the sea level. 
The greater part of the city area consists of gently inclined 
and somewhat undulating plains of gravel and sand, modified 
drift discharged from the melting ice-sheet during the retreat 
of its border upon this district. Their elevation ranges from 
about 825 feet to 915 feet; and their slopes and altitudes show 
a close dependence on the supply of drift borne by glacial riv- 
ers from the departing icefields. It was at first my expecta- 
tion that the highest parts of these modified drift plains would 
be found to give evidence of the westward extension of the 
glacial lake Hamline,* to include a part or all of Minneapolis; 
but instead these plains were formed by fluvial deposition, 
which, however, was not related directly to the Mississippi 
valley, excepting perhaps in the northwest part of the city. The 
highest plain deposit adjoins the south side of the Lowry hill 
esker, and similar plains have a gradual descent of about 90 
feet in six miles thence southeastward to the vicinity of Min- 
nehaha falls, beyond which in the next two miles to Fort 
Snelling, is a further descent of the same plain deposits 25 or 
♦Described by my former paper, "Modified Drift in St. Paul, Minne- 
sota," in the Bulletin G. S. A., vol. viii, pp. 183-196, with map, publish- 
ed February 27, 1897. 
