OTHER GLACIAL DEPOSITS IN THE VICINITY 427 



In the general northward recession of the glacial boundary, its strong 

 frontal currents of the ice heaping a part of its till, and closely succeed- 

 ing exceptionally large fluvial deposits, formed earliest the Oak Hum- 

 mock, next the Moose Nose, and latest Birds Hill, though probably nc 

 long intervals divided the times of their formation. 



Where the boundary of the ice-sheet lay eastward of Birds Hill at the 

 time of its slight readvance which spread till and many boulders over 

 the western part of that esker is perhaps indicated by the abundance of 

 boulders on the surface of the till forming the top and north slope of the 

 low hill in the northeast quarter of section 35, township 11 north, range 

 4 east, before described in connection with the east end of the esker, 

 which is three-fourths of a mile distant to the southwest, in the southern 

 part of the same section. A half to three-fourths of a mile farther north- 

 east, in the south part of section 1, township 12 north, on the cleared 

 course to be occupied by a new line of transmission of electric power, 

 very abundant boulders are similarly found on the northwestern end of a 

 wooded ridge, 50 to 75 feet high. Eastward this ridge is probably an 

 esker, and after an extent of about a half mile to the southeast and east 

 it widens into a prairie plateau or plain, composed of modified drift, 

 reaching northeast and east 2 to 3 miles or more, and having a height 75 

 to 100 feet above the extensive level lowland on the south. 



Nearly all the plateau has a surface of gravel and sand, but about 2 

 miles east-northeast from the very plentiful boulders noted in section 1, 

 a tract of several acres, distinguished from the general prairie by its 

 scattered small oaks, has man»y boulders up to 6 feet in diameter, both o| 

 granite and limestone. The surface there on a small area thus appears 

 to be marginal till, though not differing much in height or contour from 

 other parts of the general plain of modified drift. This place is close 

 east of the most western of several lone white pines, the first seen in going 

 eastward from the Eed Eiver valley. 



Connecting these places of unusual profusion of boulders, we have a 

 course of about 7 miles marked interruptedly by one of the most charac- 

 teristic features of marginal morainic drift. Therefore we may perhaps 

 rightly picture in our minds a steep frontal ice slope or cliff extending 

 along that distance from the site of Birds Hill Station to the lone pine 

 and scrub oaks, readvancing a few hundred feet and depositing its 

 boulders so plentifully in these several places. 



Belt op modipied Dript extending Southeastward 



Modified drift, consisting of stratified gravel and sand, with local de- 

 posits of clay, overlies the bedrocks and the till, and generally forms the 



