118 LIFE OF THE PLEISTOCENE 



1 . Bowmanville Low Water Satge 



The buried forest at Two Creeks, described by Goldthwait 11 is possibly 

 referable to this stage, the overlying red till being laid down by a moraine of 

 the Lake Michigan lobe during one of its advances. It has been suggested 

 by Alden 11 that it might be interglacial and referable to the Peorian interval, 

 but it seems to be related rather to the last Wisconsin episode and to be coeval 

 with the deposits which overlie the boulder clay at Chicago. Goldthwait thus 

 describes this ancient forest bed: 



"Laminated red clays formed the base of the section, up to. two or three 

 feet above the water. Above this, and separating it from a twelve-foot sheet 

 of stony red till was a conspicuous bed of peat, sticks, logs, and large tree- 

 trunks, which unmistakably represent a glaciated forest. The till immediately 

 above the forest bed, besides containing characteristic subangular striated 

 stones and red clay ismilar to the clay in the stratified beds below, all absolutely 

 unassorted, was plentifully mixed with broken branches and twigs. In the 

 underlying forest bed the stumps were well preserved, the wood being soft 

 and spongy like rotten rubber, but retaining all the appearance of its original 

 structure. Several logs and stumps lay pointing significantly towards the 

 southwest, the direction in which the ice sheet probably moved at this place. 

 One little stump, however, with its ramifying roots firmly fixed in the laminated 

 red clays, stood erect as when it grew there, but it had been broken short off at 

 the top, where the ice sheet, dragging its ground moraine along had snapped 

 off the top without uprooting the tree." 



The age of the deposit is thus commented upon by Goldthwait: "The Two 

 Creeks forest may then record an interval between early and late Wisconsin 

 time; or it may mark an interval between the Calumet stage and the readvance 

 of the ice sheet to the Manistee moraine." The writer believes the deposit 

 to be referable to the low water interval following the Glenwood stage of Lake 

 Chicago, and that the deposit underlies both the Whiteall and Manistee 

 advances of the Lake Michigan glacier. Lawson 12 records many instances of 

 the presence of old forest beds at various depths beneath the surface. Some of 

 these are doubtless to be classed with the deposits at Two Creeks, but the 

 majority appear to be referable to the Sangamon or Peorian interglacial inter- 

 vals. These are referred to in a subsequent chapter. 



Several years ago Wagner 10 recorded the finding of a specimen, of Unto 

 (Elliptio) crassidens at Green Bay. The specimen, a left valve with the 

 posterior portion somewhat broken, was found in the city of Green Bay during 

 excavation for the city reservoir. The deposit was about 15 feet below the 

 surface, and was thot by Wagner to be till, but was more likely silt. The 

 deposit may be the same as the one containing the forest remains and referable 



12 Bull. Wis. Nat. Hist. Soc, II, p. 170, et seq. 



