70 



The Ohio Naturalist. 



[Vol. VII, No. 4, 



To the north and east of this ridge the plain is higher than to 

 the west. Upon this higher ground the till is very thin if not 

 almost entirely wanting. So sparse is it that it is hard to say 

 where the till leaves off and the residual soil begins. Large 

 bowlders or erratics, however, are sparsely strewn over the sur- 

 face. Several large ones lie in Neil's Run immediately north 

 of the ridge. One of these is about 6 by 8 feet. To the west and 

 south the till, much of it stratified, increases very rapidlv in 

 thickness. The record of the State House Well shows it to be 

 123 feet (^), while another well drilled on the banks of the Olen- 

 tangy River in the city limits passed through 104 feet of drift (^). 

 Not only is the till much thicker but the large bowlders are 

 much more numerous. These occur on the surface at frequent 

 intervals and are smoothlv worn. 



Fig. 6. 

 Avenue. 



A portion of the cross section on the south side of Sixteenth 



Other instances of water-deposited glacial material occur 

 within the city limits. The excavation for the present Chemis- 

 trv Building on the State University Grounds, directly west of 

 this esker, showed deposits of the finer water-assorted material. 

 These occur in alternate strata of coar.ser and finer drift in which 



8. G. S. O. Vol. I. Part I. pp. 113-114. 



9. Ibid. Vol. VI. p. 282. 



