36 Trans, Acad. Sci. of St. Louis. 



EXPLANATION OF ILLUSTRATIONS. 



The photographic work in this paper was executed by Miss Elyse 

 Crecelius, Librarian of The Harris Teachers College. 



Plate XIII. — Fig. 1. Section of a portion of the west face of Kemp's 

 quarry, south St. Louis. The drift, 2, is coarse, lying on the clean 

 swept St. Louis limestone, 3. The contact between the drift and over- 

 lying loess, 1, is fairly sharp. — Fig. 2. Section of west face, near north 

 face, of Kemp's quarry. The contact between loess and drift is 

 unusually sharp. 



Plate XIV. — Fig. 3. Characteristic weathered granite from south St. 

 Louis drift. This material is at the point of disintegration. A is 

 pegmatite. B is biotite granite. Note the glacial planing in B. — Fig. 4. 

 A coarse granite bowlder from the sandy drift south of the Chain of 

 Rocks. Three stages of its life history are easily seen. First it was 

 water worn, becoming a round bowlder, then it was ice planed, and 

 lastly it has been weathered almost to disintegration. — Fig. 5. A very 

 compact granite bowlder, weighing 95 pounds, from the Chain of Rocks 

 bluffs. It is only slightly weathered, which is the common condition 

 of the erratics from the above sandy drift. 



Plate XV. — Fig. 6. A north and south section of a part of the Chain 

 of Rocks bluffs. Loess 20 feet or more in thickness overlies a sandy, 

 apparently fluvio-glacial, material, 40 feet or more in depth. — Fig. 7. 

 Sandy drift in the north part of Chain of Rocks park. The erosion 

 shown in the figure is the work of the rain during spring and summer 

 of 1910. Granite and basalt pebbles in a good state of preservation are 

 numerous. 



Plate XVI. — Fig. 8. Erratics from Chain of Rocks bluffs with the 

 drift in the background. This section is a short distance north of 

 Gibson Road on the Columbia Bottom Road. — Fig. 9. Typical glacial 

 bowlders from the Chain of Rocks drift. A is amygdaloidal basalt. 

 B is close textured granite planed on 4 faces. C is dark colored 

 igneous rock planed and striated. D is a compact sandstone with 

 hematite cement. E is a granite. 



Plate XVII. — Fig. 10. A little stream two miles north of the Chain 

 of Rocks pumping station, cutting through an old drift deposit, pos- 

 sibly pre-Kansan. — Fig. 11. The lower portion of a section made by 

 the above stream and its tributary. A is very old drift, possibly pre- 

 Kansan. B is a contact. C is a bed of clay between two drift sheets. 

 See previous discussion. D is a contact. E is a drift with Sioux 

 quartzite and thoroughly weathered granites and basalts, probably 

 Kansan. 



Issued April 22, 1911. 



