MAX AXD THE GLACIAL PERIOD. 655 



the expansion of Lake Agassiz on their west side, respectively 

 sixty and eighty-five miles west of Little Falls. This was 

 during the highest stage of Lake Agassiz, and previous to its 

 extension beyond the north line of Minnesota and Dakota. 

 More than twenty lower beaches of this glacial lake have been 

 traced, belonging to later stages in the recession of the ice- 

 sheet, before it was melted so far as to reduce Lake Agassiz 

 to its present representative, Lake Winnipeg. Estimated by 

 comparison with the series of moraines and beaches formed 

 during the glacial recession, the date of the gravel plain at 

 Little Falls appears to be about midway between the time of 

 maximum extent of the last ice-sheet and the time of its 

 melting on the district across which the Nelson River flows 

 to Hudson Bay. 



The town of Little Falls is on the east bank of the Mis- 

 sissippi River, in Morrison county, near the geographic center 

 of Minnesota. It is about a hundred miles northwest from 

 St. Paul and Minneapolis, and nearly an equal distance 

 southeast from Itasca Lake. The elevation of Itasca Lake 

 is about 1,450 feet above" the sea; of the Mississippi, at the 

 head of the rapids or Little Falls, from which the town derives 

 its name, 1,090 feet ; and at the head of St. Anthony's Falls 

 in Minneapolis, 796 feet. Following the general course of 

 the river, without regarding its minor bends, its descent from 

 Lake Itasca by Little Falls to Minneapolis averages about two 

 feet per mile, and is approximately uniform along the entire 

 distance. Considered in a broad view, this central part of the 

 State may be described as a low plateau, elevated a few hundred 

 feet above Lake Superior on the east and the Red River Valley 

 on the west. . In most portions it is only slightly undulating 

 or rolling, but these smooth tracts alternate with belts of 

 knolly and hilly drift, the recessional moraines of the ice- 

 sheet, which commonly rise fifty to one hundred feet, and in 

 the Leaf Hills one hundred to three hundred and fifty feet 

 above the adjoining country. The bed-rocks are nearly every- 

 where concealed by the drift-deposits, into which the streams 

 have not eroded deep valleys, their work of this kind being 

 mostly limited to the removal of part of their glacial flood- 

 plains. The upper portions of the Mississippi and of its 



