STRUCTURE OF THE DRIFT BORDER. 53 



Along- the crest of the terminal ridge from Skunk River southward to 

 West Point numerous wells have been sunk to a depth of 60 feet and a few 

 to greater depth. They penetrate till the greater part of the depth, though 

 in one instance the lower 50 feet is sand and gravel. The thickness of the 

 drift ranges from about 80 to 120 feet or more. Of this the lower 40 or 50 

 feet is older than the Illinoian. Several of the wells have passed through 

 peat, containing wood, at about the level of the base of the ridge, and 

 there is an excellent exposure of a black muck below the Illinoian drift in 

 a ravine about a mile northeast of West Point on the east slope of the ridge. 

 At this exposure the following section is found : 



Section in a ravine about a- mile northeast of West Point, Ioiea. 



Feet. 



Yellow silt or loess (Iowan) (i 



Soil, -with ashy gray subsoil (Sangamon) 5 



Brown till containing many bowlders (Illinoian) 15 



Black mucky soil with gray subsoil (Yarmouth) 6 



Brown clay with few pebbles (Kansan) exposed 15 



Total 47 



The deepest well section obtained on this ridge is at the residence of 

 Andrew Foggy, sec. 16, T. 69, R. 5 W., and this differs from other well 

 sections in that neighborhood in containing- a large amount of sand in the 

 lower part. From observations in a neighboring- ravine and Mr. Foggy's 

 statements concerning material penetrated in the well, the following section 

 is prepared: 



Section in well of Andrew Foggy, near West Point, Iowa. 



Feet. 



Yellow silt or loess (Iowan) 6 



Black soil with gray subsoil (Sangamon) 4 



Yellow till (Illinoian) 20 



Sand, affording weak vein of water (Illinoian) 6 



Blue till (Illinoian) 33 



Sand and peaty material, underlain by a Sne gravelly sand (alluvial and Kansan) 50 



Limestone 12 



Depth 131 



It is probable that the Illinoian drift extends to the peaty material at a 

 depth of 70 feet, for the well stands upon probably the most elevated point 

 on the ridge in this county, at a level nearly 70 feet above the outer border 

 plain. A neighboring well in the same section, on the farm of F. Timpe, 

 penetrated about 12 feet of loess-like silt and slightly pebbly yellow clay, 

 at which depth a very calcareous, sandy, yellow till is entered. This 



