34 Trans. Acad. Sci. of St. Louis. 



millimeter to IIK^ millimeters. These particles are for 

 the most part glassy quartz, weathered chert, and iron 

 concretions. Portion B contained fifty-eight pieces, 

 weighing ninety-two milligram's. In this portion there 

 were seven well -rounded water-worn pieces. Otherwise, 

 as regards shape, size, and composition, there was a 

 general agreement with the fragments of portion A. 



For purpose of comparison, fifty grams of thoroughly 

 dried St. Louis loess, with the typical columnar struc- 

 ture and open texture were treated in the foregoing 

 manner. Fifty particles, chiefly angular, varying from 

 three-fourths millimeter to 3 millimeters, weighing 82 

 milligrams, failed to pass through the sieve. Three 

 pieces were completely rounded, as if water-w^orn. The 

 particles determinable are quartz, weathered chert, iron 

 concretions. One rock crystal, 2yo millimeters long, was 

 obtained which showed scarcely a trace of water action. 

 From this it appears that there is a close agreement be- 

 tween the St. Louis loess and loess overlying the upper 

 drift sheet mentioned in the next paragraph. But the 

 clay of this section differs from the loess in several es- 

 sential details. 



The drift on top of the clay (Fig. HE), is about ten 

 feet thick. In the section near the bridge a bowlder of 

 feldspar and quartz porphyry, in a fair state of ])reser- 

 vation, was found lying at the top of the upper drift, 

 overlaid l)y loess ten feet thick. The igneous material 

 of this section is much less weathered than that of the 

 lower sheet. The lower deposit also contains more 

 Lafayette material than the upper. In this respect the 

 drift patches in St. Louis agree with the lower deposit, 

 pointing to a similar origin. 



On the whole, this is a very interesting section. Three 

 sharply-drawn contacts may be easily seen. The contact 

 between the lower drift and the interglacial clay and that 

 between the latter and the overlying drift are remarkably 

 sharp. In places a ruler, one inch wide, laid horizontally 



I 



