544 ROLLIN T. CHAMBERLIN 



Above this section is a long slope with a rise of 35 feet to the highest 

 river terrace. This old drift may therefore once have been fairly 

 thickly covered with Wisconsin drift, since removed by the river. 



One hundred pebbles averaging an inch in diameter were dug 

 from the brown calcareous till (No. 2), and classified with the follow- 

 ing result : 



Fine-grained greenstones 29 



Limestone 21 



Granite (10 pink, 8 gray) 18 



Gabbro-diorite 6 



Quartz 4 



Greenstone schist 3 



Quartzite 3 



Quartzose . 3 



Brown sandstone 3 



Syenite 2 



Mica schist 2 



Red Lake Superior sandstone 2 



Chert 2 



Monzonite i 



Red porphyry i 



100 



The greenstones were largely of the dark Keewatin types. There 

 seemed to be very little even among the gabbro-diorite group to 

 suggest the Keweenawan lavas of the Lake Superior Basin. The 

 glacier which deposited this drift received but little material from 

 Lake Superior or from earlier Labradorean drifts. 



Three miles east of Dresser Junction (T. 33 N., R. 18 W., Sec. 11, 

 S.W. corner) the wagon road descending into a deep valley exposes 

 a buff clayey till streaked through and through with silver-gray and 

 bluish-gray portions like the typical banks of Kansan drift in Iowa. 

 The calcareous material has been leached out of this oxidized portion 

 of the till. The unaltered black drift was not seen. Fifty pebbles 

 from this till were classified as follows: 



Percentage 



Granite 12 24 



Quartz 10 20 



Fine-grained greenstones. 8 16 



Chert 5 1° 



Feldspar crystals 5 10 



Syenite 3' 6 



Gabbro-diorite 3 6 



Quartzite 2 4 



Clay ironstone i 2 



Decayed igneous _i 2 



50 100 



