NOTE ON THE GLACIAL DRIFT IN ST. LOUIS. 

 H. A. Wheeler, E. M. 



(Read In somewhat less extended form at the meeting of the Academy of Science, 



April 1st, 1892.) 



In driving a tunnel under West Pine street, in the western^cen- 

 tral part of St. Louis, for a sewer, the blue glacial clay or " till " 

 was found for a distance of about 2,000 feet. A shaft at the 

 junction of Taylor avenue and Pine street, which was about 

 the middle of the till formation, disclosed a thickness of 12 

 feet. The blue-clay carried gravel and boulders as usual, 

 and though none of the latter exceeded a foot in diameter, 

 they were largely made up of distant-carried material, or 

 crystalline rocks from the North like granite, mica-schist, 

 white-quartzite, besides white saccharoidal sandstone, chert 

 and limestone. It rested on the St. Louis Limestone (sub- 

 carboniferous), and was overlaid by 10 to 15 feet of the 

 non-pebble bearing loess, or the unstratified, columnar 

 jointed, brown, homogeneous sandy-clay formation (the 

 "brick-clay"). The till feathered out on the west side of 

 Euclid avenue, and was not again encountered in the westerly 

 extension of the sewer. 



From the limited width of the till, as the sewer-section was 

 on about an east and west line, and the comparative thinness, 

 not exceeding 12 feet, it seems to be a local tongue or exten- 

 sion of an ice-stream beyond the main body of the southern 

 limit of the great ice-sheet. The nearest recognized develop- 

 ment of the till is at the Chain of Rocks region, or ten to 

 fifteen miles north, where heavy sheets of mixed gray and 

 brown clays and sands, carrying pebbles and boulders of 

 foreign rocks, occur in the tongue of land between the Mis- 

 sissippi and Missouri rivers. In this region the till attains a 

 thickness of over thirty feet, and contains, as erratics, red 

 pegmatite, granitite, red and gray granite, diorite, dolerite, 



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