GLACIAL FEATURES OF ST. CROIX DALLES REGION 251 



ment; the second, formed as the lateral edge of the ice-lobe came 

 nearer to the rocks in question, deviate about 28 more to the east; 

 while the last, produced near the edge of the ice, trend 30 more to 

 the east. A progressive turning toward the border of the lobe is 

 thus shown. This is in accordance with the law of ice-flow in broad, 

 flat lobes. The general direction of movement of the Lake Superior 

 lobe was southwesterly, but on this, the left flank, its advance was 

 southeasterly toward the ice-edge. The dotted lines on the striae 

 map are attempts to show this. 



Bowlder trains are not of great service as indications of the direc- 

 tion of ice advance in this region, as they are poorly developed. 

 In the lee of only one prominent outcrop — a mile and a half east of 

 Dresser Junction— are the fragments of diabase conspicuous. There 

 bowlders occur in great numbers on the east side of the rock hill. 



WORK OF THE KEWATIN GLACIER 



Some time after the Superior glacier had withdrawn, the Kewatin 

 sheet, coming down the Red River valley, advanced from the west 

 to the middle of the Dalles quadrangle, spreading its drift over the 

 previous red deposits. This younger drift is strikingly different 

 from the older in several particulars. Its color is a grayish buff, 

 somewhat like that of the drift of southern Wisconsin, though lacking 

 the brownish ferruginous tints. Frequently the surface layer which 

 has been leached exhibits a more yellowish or brownish shade than 

 the unaltered till, due to the oxidation of the iron compounds. While 

 the red drift is sandy, the gray is clayey; the former, as previously 

 noted, contains neither limestone nor shale, both of which abound 

 in the latter. Since much of the western drift is the product of 

 limestone ground up, it follows that it is highly calcareous, except in 

 the upper foot or two where leaching has occurred. The red drift 

 is non-calcareous. Part of the limestone, and most of the dark 

 gray shale which is so characteristic, were probably derived from the 

 Cretaceous strata of western Minnesota and the Red River valley. 

 However, a few Trenton fossils found in the glacial pebbles prove 

 that the Cretaceous series was not the source of at least a part of the 

 limestone in the gray drift. 



Gray drift covers all the territory in the quadrangle west of the 

 river, with the exception of some small patches of red drift over which 



