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THE POPULAR SCIENCE MONTHLY. 



the gravel and sand of No. 2, or they may be mostly embedded in 

 No. 3. The thickness of No. 2 is exceedingly variable. It is usually 

 less than forty feet in level tracts, but it may be more than a hundred, 

 depending on the duration of the cause that brought it there, and its 

 operation at that point. It sometimes probably entirely replaces No. 

 3 and No. 4, and lies on the rock. The bowlders found within it are 

 generally not scratched, but sometimes they are scratched, evidently 

 by glacier-action. A great number of glaciated bowlders in this mem- 

 ber of the drift have been seen at an excavation near the Falls of St. 

 Anthony. 



The following diagrams, Figs. 1 and 2, will express more fully the 

 arrangement of the strata in this member of the drift, and give an idea 

 of the manner of union with the succeeding member below. Fig. 1 is 

 sketched from Nature, and shows a section of the laminated clay ex- 

 posed in a railroad-cut near Toledo, Ohio : 



Fig. l. 



NATURAL SURFACE. 



Section of the Laminated Clay (Clay Subsoil), Toledo, Ohio, showing its Junction with the 



HAitD-rAN op the Drift. 



a. Horizontal laminations of tine clay and sand. 



b. Oblique laminations of fine clay and sand. 



e. Detached masses of hard-pan clay, variously mingled and united with the laminated clay. 

 d. The upper portion of the great hard-pan sheet. 



Fig. 2 is also sketched from Nature, and represents the alterna- 

 tion of parts as seen in No. 2, and manner of junction with No. 3 at 

 the Falls of St. Anthony. No. 2 here consists of the stratified gravel 

 and sand which constitutes the surface of the drift (immediately be- 

 low the soil) in large portions of the State of Michigan, Central and 

 Southern Ohio, Northern Indiana, and Central Minnesota. It also 

 forms the principal component of the well-known ridges in Northwest- 

 ern Ohio, popularly but erroneously styled " lake-beaches." The ma- 

 terials are usually much water-worn, but, at the Falls of St. Anthony, 

 many of the bowlders embraced in No. 2 are conspicuously glacier- 

 marked, a circumstance which plainly indicates the agency which 

 transported and deposited the whole mass in which they occur. 



