EXPLANATION OJ^ PLATES 341 



Explanation of Plates 



Plate 27. — Map and Profiles of the Keweenawan of eastern Minnesota 



Figure 1. — Map of eastern Minnesota. 



This map of the Keweenawan area of eastern Minnesota shows the 

 exposures of Keweenawan rocks ; the position of the fault line 

 which marks the limit of the Keweenawan to the north and west, 

 and the assumed limit of the lava flows toward the southeast. The 

 contour lines for Minnesota are taken from the several county maps 

 of the Geological Survey of Minnesota; for Wisconsin approxi- 

 mated from the elevations of Upham and Gannett, Bulletins 72 

 and 160, United States Geological Survey. 



Figure 2, — Profile of the Chengwatana series of lava flows and conglomerates. 



The thickness of the several beds is given as measured along the 

 banks of the river. The total thickness of the conglomerates is 

 216 feet and of the lava flows 3,800 feet, making a total of over 

 4,000 feet of exposed beds with both underlying and overlying 

 beds concealed. 



Figure 3. — The succession of lava flows at Taylors Falls. 



This is as they are shown in the Dalles and along the slope westward 

 through the village to the prairie level. At the top of several of 

 the flows are beds of tufi" and ash, and at one place there is a 

 markedly brecciated clastic. 



