VO CHICAGO ACADEMY OF SCIENCES. 



A few gravel pits have been opened in this beach. Probably 

 the most extensive is Haas' pit, near Forest Home Cemetery, one 

 mile south of Oak Park. This is opened in the bar described 

 above as leading southward on the east side of the Des Plaines 

 River. The excavation extends from the east side of the bar west 

 past the center and shows beds dipping at various angles, but all 

 towards the east. Some of the beds increase in thickness as they 

 descend, but the lower bed which is mainly sand decreases in thick- 

 ness in passing from the higher to the lower part of the bar. It 

 appears to be a sand bar upon which the coarser beach deposits 

 are built. The following section was obtained at the south side of 

 this gravel pit and shows the structure at that particular place 

 only, for Mr. Haas states that the material of the same bed may 

 vary greatly in coarseness within the space of a few feet. The dip 

 of the beds, however, is uniformly toward the east, throughout the 

 entire extent of the pit, which covers an area of several acres : 



1. Brown-stained gravel, capping summit and slope. ..... i8 to 30 inches 



2. Fine gravel, fresh or stained but little. ............... 24 to 48 



3. Sand, very thin at top, but increasing toward side of bar o to 36 " 



4. Fine gravel, increasing like No. 3 o to 48 " 



5. Fine gravel, nearly 4 feet in thickness, which passes 



upward from near the east side of the excavation, as- 

 suming a nearly horizontal position beneath the crest 

 of the ridge ••.... 40 to 48 " 



6. Sand, thickening toward the higher part of ridge 6 to 36 



Mr. Haas reports that shells of the size of unios and also 

 smaller molluscan shells have been found in the bed of sand at the 

 bottom of the pit. The larger shells were thought by him to be 

 unios. A shell, however, which he sent to the writer proved to be 

 the ordinary oyster. This unexpected development raises the 

 question whether this particular shell was in situ at the time it was 

 discovered, if it does not render doubtful the occurrence of any 

 native shells in this bar. Upon visiting the region again and in- 

 quiring particularly into the circumstances, there seems little ques- 

 tion that the shell was picked up near the base of the pit by some 

 of the workmen, but it was found that there are a few Indian graves 

 on the bar, which extend down nearly to the level of the base of 

 the pit. The shell, therefore, may have been introduced at the 

 time of burial of some brave warrior, or it may have been of more 

 recent introduction. This is apparently the only place along the 

 entire length of the upper beach where molluscan shells have been 



