122 Trans. Acad. Sci. of St. Louis. 



quartz porphyry (like the Keweenaw Point series), porphy- 

 rite, red quartzite, quartz geodes (Keokuk), white " sugary " 

 sandstone (Saecharoidal), besides abundant cherts from the 

 immediate neighborhood. But no blue-clay has been observed 

 there, and the Pine street sheet is the only occurrence of blue 

 till known to the writer in Missouri that is south of the 

 Missouri river, which lies 12 miles north. 



A thin layer of gravel bearing loess (?) is usually found at 

 the base of the true loess throughout St. Louis County, as far 

 as 10 to 15 miles south of Pine street, and while most of the 

 pebbles are local cherts, they occasionally include distant 

 material like granites, etc. This gravel bearing bed is always 

 thin, ranging from -|^ to 2 feet in thickness and is similar in 

 character to the transition bed that is found about the Chain 

 of Rocks region between the typical loess and the typical 

 drift, or has the general character of the loess plus more or 

 less gravel, though usually only a little gravel is present. It 

 totally lacks the character of the true till, and cannot be 

 regarded as an ice-sheet deposit. This Pine street occurrence 

 of till is therefore the most southern known extension of the 

 ice-sheet in St. Louis County, though the Illinois lobe 

 advanced considerably further south, according to the studies 

 of Leverett, Salisbury, Chamberlain, and others. 



I am indebted to Mr. Robt. E. McMath, the former 

 sewer-commissioner, for calling my attention to the Pine 

 street blue-clay. 



Issued February 21st, 1895. 



