OLDER DRIFTS IN THE ST. CROIX REGION 547 



of the cut is a bank of red Wisconsin drift. Fifty pebbles from this 

 gravelly deposit under the Wisconsin drift, taken from a point six 

 feet above the Franconia sandstone, were classified as follows: 



Percentage 



Fine-grained greenstones 14 28 



Red Lake Superior sandstone 7 14 



Red quartz porphyry 4 8 



Jasper 4 8 



Brown sandstone 4 8 



Granite 4 8 



Gabbro-diorite 3 6 



Quartz 3 6 



Red diorite 2 4 



Red aphanitic 2 4 



Quartzite 2 4 



Decayed igneous i 2 



50 100 



This is clearly a Lake Superior drift brought in by an ice-advance 

 from the I^abrador gathering-ground. 



This lower red-brown drift is older than the Wisconsin red drift 

 and younger than the grayish-black drift of supposed Kansan age. 

 The nature of its occurrence within the St. Croix-Dalles quadrangle 

 does not afford any very tangible clue to the age of this deposit. 

 But it appears to be almost identical in lithological characteristics, 

 degree of induration, and various minor pecuharities with the sheet 

 of pre-Wisconsin red drift which forms the prominent moraine near 

 the village of Hampton in central Dodge County, Minn. This is 

 fifty miles S.S.W. of Osceola. In this moraine the hummocks still 

 persist, though they have been much sharpened by slope-wash and are 

 now peaked or conical in shape. From the amour. t of erosion and 

 general appearance of this drift it seems perhaps best to assign it 

 for the present t3 the Illinoian glacier from the Labrador center. 



Similar pre-Wisconsin red drift overlies the grayish-black till 

 in many cuts along the line of the Northwestern Railroad between 

 Hersey and Baldwin, Wis. Some of these exposures show that a 

 considerable interval of time elapsed between the retreat of the ice- 

 sheet which deposited the grayish-black drift and the advance of 

 the glacier which brought the red drift. The buff-weathered phase 

 is present above the unaltered grayish-black till, and in some places 

 this yellow oxidized till has been leached down five or six feet below 



