366 ARTHUR C. TROWBRIDGE 



careful search for erratic bowlders in the valleys of the north and 

 south forks of Messenger's Creek. An hour's search revealed 103 

 such bowlders in the valley of the north fork, and an equal time in 

 the valley of the south fork failed to discover one. The highest 

 igneous rock bowlder in the north fork is at 1,162 feet, 202 feet 

 above present lake-level, and only 28 feet lower than the divide 

 across which the lake-water must have drained. Glacial cobbles 

 occur within 16 vertical feet of the divide, and one diabase cobble 

 was found on the west slope of the divide in the drainage of Skil- 

 lett's Creek. 



It is concluded, therefore, that during the Wisconsin epoch 

 the waters of Devils Lake stood against the glacier at the north 

 end, formed a bay up the valley to the northeast about as far as the 

 north-south road in the Peck flat, reached to about the level of 

 Elephant's Rock on the east bluff, stood against the ice at the 

 southeast extremity of the basin, extended to within a short dis- 

 tance of the head of the south fork of Messenger's Creek, and spilled 

 over the divide at the head of the north fork of Messenger's Creek, 

 as shown in Fig. 1 and Fig. 4. Through this outlet the water 

 flowed west into a larger lake, known as the Upper Baraboo Lake, 

 now extinct. 



THE POST-GLACIAL LAKE 



As the edge of the glacier receded during the closing stages 

 of the Wisconsin glacial epoch, the high level of the lake and its 

 westward-flowing outlet may have been maintained for a time, but 

 when a connection was established between Devils Lake and a lake 

 which came into existence in the Baraboo valley, and whose surface 

 stood at a lower level, the waters of Devils Lake were lowered to the 

 lowest point in the morainic dams. The lowest point on the surface 

 of either moraine was a little east of the middle of the gap at the 

 north end of the lake, along the site of the railroad and wagon road 

 from the lake to Baraboo. The original level of this outlet is not 

 known, because it has now been cut almost to lake-level, but the 

 edges of the outlet gap on the surface of the moraine at either side 

 are at about 1,020 feet, or 60 feet above present lake-level. This 

 is approximately the level of the surface of Devils Lake after the 

 retreat of the ice, and before the outlet had been lowered appreciably. 



