282 The American G'eologitit. May, 1895 
Mitchell, Minn., 200 to 250 miles inward from its farthest lira- 
its in North Dakota and on the northern boundaries of the 
Wisconsin driftless area, but 500 miles Jiorth from its limits in 
northeastern Kansas and in Missouri. During its later Ifuvan 
stage the ice-sheet reached from Barnesville about 200 miles 
westward into North Dakota, an equal distance eastward into 
northwestern Wisconsin and northeastern Minnesota, and 
some 350 miles or more south-southeastward in Iowa. A mar- 
ginal moraine, which had been formed probabl}- during a 
pause or reiidvance interrupting the later part of the inter- 
mediate glacial retreat, is indicated by exceptionally abun- 
dant boulders in a stratum of the drift shown in the bluffs of 
the upper part of the Minnesota river valle}^ and by its tributa- 
ries, overspread by 25 to 50 feet of the later lowan and Wis- 
consin till deposits,* according to Chamberlin's classification 
of these drift formations before cited. 
Among the species making up the interglacial forest bed in 
northeastern Iowa, McGee reports the cedar {J loiiperus vir- 
(jiniana) as far the most abundant; its other identified coni- 
fers are pine, spruce, and tamarack; and its deciduous trees 
and shrubs comprised species of oak, elm, walnut, hickory, 
sumach and willow. Its only observed traces of animal life 
represent an extinct species of horse [Eqvus com pi icatus)^ 
the wood rabbit, and the common skunk. -j- In southern and 
western Minnesota, besides the observations of interglacial 
forest trees and peat, numerous wells have yielded small mol- 
luscan shells, considered to be like those of the present lakes 
and sloughs of the same region, in deposits which here are re- 
garded as S3nichronous with the principal forest bed, belong- 
ing to the time of glacial recession before the lowan till form- 
ation. 
Much later, between the times of formation of the Elysian 
and Waconia or fifth and sixth moraines of the series mapped 
in Minnesota all of which are referred to the late Wisconsin 
stage or epoch of the Ice age, I find evidence of a reiidvance 
*Gcol. of Minn., vol. i, pp. 62(5-628, including also notes of the trans- 
portation of red till and masses of copper from the lake Superior region 
to a farther distance soulhwestward during the Kansan stage than in 
the later stages of glaciation. 
fU. S. Geol. Survey, Eleventh Annual lieport, p. 1!)."). 
