BULL. GEOL. SOC. AM. 



VOL. 26, 1914, PL. 7 



Figure 1. — Cavern cut Across by GLACi.iL Erosion 



Greatest wiJth about IS inches. Note sharp angle between glaciated and unglaciated 

 surfaces even where cavern extends parallel to the stria; 



oj9'~- 



X 



V 



ProDRE 2. — An Enlarged joint Cavern 

 Upper foot smoothed and striated by ice : proof of pre-Glacial age of solution effects 



I'h.l Ul. 



\\ i.A ui ii.i.u Si K I w I . •! 1 ,1 I I - I . . ^ I I; I \ i.u.i;ii r. \ i.ii \i;i: n S iui I'l'l ng 



Note the enlarged Joints; also ihr snluiion piis nii ihr top surfaci' nl' ihc liriu>stone. The 

 arrow iinints Id llic cmly spol within llir I'k'IiI hI virw wliicli was Imu-hcd l)y the ice 



PECULIARITIES OF GLACIAL ERO.SION IN CENTRAL ILLINOIS 



