Drushel — Glacial Geology in St. Louis and Vicinity. 29 



lor avenue, and the ''waxy red elay" described by Todd,^ 

 as occurring on Laclede, near Sarah street. 



A short distance southwest of the section just de- 

 scribed and northwest of the Shaw School, at an eleva- 

 tion of 560 feet, may be found a region of pebbly material 

 beneath the loess. An area of a block of the latter having 

 been removed by the Laclede-Christy Clay Company, an 

 excellent study of the pebbly material is afforded. On 

 account of tlie presence of granite pebbles and other ig- 

 neous material this deposit should be regarded as drift. 

 The gullies heading in this region often show igneous 

 material, which doubtless was derived from the sheet 

 above described. 



It is proper to remark at this point that a careful 

 search in the pebbly clay below the loess, which has 

 sometimes been considered a portion of the loess, will, in 

 most cases, reveal igneous material. On this account, 

 and because of the nature of the clay itself, and because 

 the contact in some places between loess and pebbly clay 

 is sharply drawn, this clayey formation should probably 

 be considered a true bowlder clay. For contact see Fig. 2. 



In the Chain of Rocks region is a deposit which differs 

 much from the drift described heretofore. The deposit 

 is characterized by great thickness; by the presence of 

 much sand, and of numerous igneous bowlders and peb- 

 bles, a cubic foot of material showing 100 pebbles and 

 bowlders of a length greater than one centimeter and less 

 than thirty centimeters, half of this material being 

 igneous; and by the small amount of the stiff bowlder 

 clay. This is a continuous deposit, as shown by the 

 numerous gullies, from Coal Bank road, on the north, to 

 (ribson road, on the south, a distance of two miles or 

 more. A few rods north of Gibson road, in a small ravine 

 drift may be seen lying on Coal Measure shale at a few 

 feet elevation above the Columbia Bottom road. The 

 erratics are unusually large for this region. Several, one 



'J. E. Todd. Missouri Geol. Surv. 10:162-163. 1896. 



