246 ROLLIN T. CHAMBERLIN 



miles from the St. Croix moraine, and as low as 960 feet, but its 

 basin has escaped filling by outwash material. Less than a mile 

 northeast of the extremity of the lake flat, the outwash plain ends 

 at the 1,140-foot contour. East Lake is still nearer the moraine, 

 but on the east side of the lake, one mile from the terminal, no strati- 

 fied drift is found, from the 1,100-foot hilltops to below 1,000 feet, 

 where the hill has been modified by the lake when at a higher level 

 than now. 



The reason for this considerable area of ground moraine, almost 

 unaffected by the St. Croix outwash, though at a low level, is found 

 in the established drainage lines. Previous to the outwash deposits, 

 a well-developed drainage channel existed from the Dresser Junction 

 neighborhood, past East and Horse Lakes, following what is now 

 the Horse Creek valley, to the Apple River. When the glacier front 

 stood at the St. Croix moraine, the streams from the melting of the 

 near-by ice quickly collected in this course, producing sufficient 

 volume and velocity to prevent extensive aggradation of the channel. 

 Gathered into one course, the rivulets from the immediate neigh- 

 borhood did not spread out over the country to the east, whose hills 

 and marshes remained unaltered. However, several miles farther 

 east, in the vicinity of the two Horsehoe Lakes, streamlets from the 

 north, which avoided the Horse Creek drainage system, have been 

 able to spread much farther south, where they have partially filled 

 in the low, marshy areas four and five miles from the moraine. 



The Dresser Junction gap. — When the ice stood some distance 

 west of the St. Croix moraine, possibly while at the Franconia reces- 

 sional, perhaps not so far, the. high St. Croix morainic ridge blocked 

 the drainage from the melting ice. As a result, the water ponded 

 between the moraine and the ice-sheet until it rose to the lowest 

 point in the barrier ridge, which happened to be at Dresser Junction, 

 whether by chance, or because of the influence of a pre- Wisconsin 

 channel at this point. Upon reaching the proper height, the overflow 

 cut the barrier down rapidly ; for, having dropped most of its load in 

 the ponded portion, the water was relatively clear. The Horse Creek 

 channel was still further eroded and the gap lowered nearly to this 

 level. In later times, when the gray ice advanced to Dresser Junction, 

 its outwash went through the gap. The extensive flat east of Osceola 



