498 W. UPHAM STAGES OF THE ICE AGE 



which interrupted the Ice Age in the southern half of Minnesota, is sup- 

 plied by the exceptional chains of lakes before noted in Martin County, 

 one of the central counties in the southernmost tier of this State. These 

 chains of lakes are three in number and are named the East, Central, and 

 West chains, 



South Creek receives the outflow from the East chain, which extends 

 in a somewhat irregular northerly course for 12 miles from the Iowa line. 

 This chain comprises eight lakes, varying from a half mile to two miles 

 in length, with from a half to two-thirds as great widths. These lakes 

 are bordered by rolling areas of till. Their shores ascend 30 to 40 feet, 

 mostly by quite steep slopes. The spaces between the lakes are, in some 

 cases, marshy and as wide as the narrower parts of the lakes, but other 

 adjoining lakes are connected by contracted channels, such as might be 

 cut by the outflowing stream. Thus the series does not occupy depres- 

 sions in any well marked and continuous valley. 



About twenty lakes are included in the Central chain, extending 22 

 miles in an almost perfectly straight north to south course, from Perch 

 Lake, three miles south of Watonwan County, to Iowa Lake, which is 

 crossed by the State line. This series of lakes lies three to six miles west 

 of the East chain. Its outlets are South, Center, Elm, and Perch creeks, 

 all flowing eastward. 



On both sides of the Central chain of lakes, as in the case of the East 

 chain, the adjoining country consists of till, which rises to a moderately 

 undulating expanse, 30 to 40 or 50 feet above the lakes. Though form- 

 ing a very distinct, straight series, these lakes do not occupy a well de- 

 fined valley, for its width varies from one mile or more to less than. an 

 eighth of a mile, and it is interrupted in three places by water-divides 

 which are 10 to 15 feet above the adjoining lakes. Silver and Iowa lakes 

 are the headwaters of South Creek, and have their outlet by a stream that 

 runs nearly along the State line to the south end of the East chain. The 

 middle part of the Central chain, reaching 12 miles from Summit Lake 

 to the Twin Lakes, is tributary to Center Creek, and its portion farther 

 north, excepting Perch Lake, is within the belt drained by Elm Creek. 



The West chain of lakes is less distinctly connected than the East ami 

 Central chains, from which it also differs in having the longer axes of 

 some of its lakes transverse to the course of the •chain, and in having 

 shorter series of lakes joined with it as branches. Tuttle's Lake, at the 

 south end of the chain, lies on the State line about four miles west of 

 Iowa Lake, the south end of the Central chain. Thence the West chain 

 reaches 20 miles northwesterly, then nine miles northerly, and then north- 



