228 FREDERICK W. SARDESON 



ing subsoil between them. The folds previously mentioned as 

 seen at St, Paul are dry, and they differ from this one in being more 

 uniform from top to bottom and in the less weathered condition 

 of the stone. They resemble more closely the fold formed by glacial 

 action, which will be next described. 



This clearest case of glacial folding occurs at the site of the new 

 lock and dam, No. i, on the Mississippi River above the mouth 

 of Minneliaha Creek, in the southeastern part of the city of Min- 

 neapolis. Here a new roadway is cut down the face of the river's 

 bluff, exposing a fresh section of part of the limestone and shales 

 of the Galena series and of part of the glacial drift. This section 

 of the fold is represented in Fig. 2. The roadway passes the 

 fold twice in descending the bluff in its first case cutting a gravel 

 bed (/) and glacial till (G) lying over the fold, and in its second 

 cutting obliquely across the fold and part of the undisturbed strata 

 beneath it. From the first cutting the fold can be seen to extend 

 a distance of several rods. The parts represented in the entire 

 section (Fig. 2) are normally: 



/. Glacial gravel 8' 



G. Glacial till 8' 



5 5. Gray crystalline limestone o' 8" 



4. Green clay-shale 2' 6" 



3. Gray crystalline limestone 2' a," 



2. Green clay -shale o' 4" 



I. Dark crystalline limestone 1' 6" 



B. Massive granular limestone 5'-l- 



When folded up, the stratified rocks which in their normal position 

 would comprise 3 feet of hard crystalline limestone and 2 feet 10 

 inches of compact clay-shale, or about 6 feet in all, in their disturbed 

 condition make up 15 feet of broken limestone and shales. The 

 overlying glacial deposits are made thinner than they are normally,, 

 as shown in Fig. 2. The limestone strata, 5 i and B, beneath the 

 fold, are not disturbed. 



It is evident from the section that the strata which are locally 

 folded were thrust together, sliding upon the clay-shale layer, 82^ 

 and that the upheaval resulted from the fracture and upheaval of 

 the resisting layers. The overthrust on the right or northeast side,. 



