356 PLEISTOCENE OF INDIANA AND MICHIGAN. 



PEATY DEPOSITS. 



Deposits of peaty material found under portions of the Calumet beach have been inter- 

 preted to signify that the lake level stood lower than the Calumet beach at a time prior to the 

 development of that beach. A conspicuous burial of peat under the gravel of the Calumet 

 stage of the lake is found in Evanston, 111., where the gravel extended southward as a bar into 

 a bay that stood back of the present city. A recent exposure of peat below the Calumet beach 

 at Bowmanville is noted by F. C. Baker. 1 However, although the presence of peat under the 

 gravel suggests a lower stage of water it can scarcely be said to prove it conclusively, for a 

 bar might be extended out over a peaty deposit standing at the same level as the lake and 

 might press it down and thus give it a lower level than it had while in process of growth. At 

 the Evanston locality this interpretation would seem very plausible, for the bar was built out 

 into water of considerable depth by southward-moving currents. Other peaty deposits are 

 extensively covered by the gravels of the Calumet beach along the bluff of Lake Michigan 

 between Michigan City, Ind., and New Buffalo, Mich. In this place there seems to have been 

 no bar, but a regular beach. The peat ranges from about 15 feet above the lake down to the 

 water's edge. The layers, few of which are more than 6 inches thick, are interbedded with sand. 

 One layer standing 12 to 15 feet above the lake is traceable continuously for fully half a mile 

 along the shore about 2 miles southwest of New Buffalo. Near Michigan City the peaty layers 

 are continuous just above the water's edge for a mile or more. Pebbly sand above the peaty 

 beds in places reaches an elevation of 30 feet or more above the lake or nearly to the level of the 

 Calumet beach. The sand evidently was deposited during the development of that beach and 

 the peat is certainly as old as the beach. The beach may have been extended out over a peaty 

 deposit, as was suggested in the case of the Evanston deposits , but the conditions on the whole 

 do not strongly favor this view. If a lower lake level preceded the development of the Calumet 

 beach other evidence than that from the buried peat deposits should be found. For instance, 

 the valleys which entered the lake at this lower stage should have been cut to a level below the 

 Calumet beach and then the beach should have been built across the beds of these channels 

 as the Whittlesey beach was across the valleys that were cut to the level of Lake Arkona in 

 eastern Michigan. 



TOLESTON BEACH. 



DISTRIBUTION. 



A third beach of Lake Chicago which was barely high enough to open into the Chicago 

 outlet has received the name Toleston from a village situated on it in northwestern Indiana 

 (now absorbed by the city of Gary). The beach, which lies 18 to 25 feet above the level of 

 Lake Michigan, is preserved in much of the Indiana portion and in the Illinois portion as far 

 north as Evanston, but is generally cut away on both shores of Lake Michigan north of a line 

 running from Evanston, 111., to Michigan City, Ind. 



The Toleston beach appeared to be present at Holland, Mich., at the eastern end of Black 

 Lake, being built out between the lake and the marsh which extends east from Holland a short 

 distance. It is there built up to a height of 21 to 22.5 feet above Lake Michigan, as shown by 

 Goldthwait's levels. From Holland it seems likely to have continued northward to Grand 

 River, but as that region is extensively covered with sand blown from the modern shore the 

 beach is largely concealed. In Springport Goldthwait's levels show the beach to be about 

 21 feet above Lake Michigan. From Grand River it appears to run northwestward, passing 

 just east of Little Black Lake on the line of Muskegon and Ottawa counties and coming to the 

 shore of Lake Michigan directly west of the north end of the lake. There is probably no point 

 between Holland and Grand River where its distance from the present shore exceeds 6 miles, 

 and throughout much of the distance it probably does not exceed 2 or 3 miles. 



The beach has very little development in the recesses of the shore in Muskegon, Oceana, 

 and Mason counties and so far as developed appears to be not more than 25 feet above the 

 level of Lake Michigan. 



1 Science, new ser., vol. 31, 1910, p. 715. 



