68 



GBOIvOGY OF I.A SAIvLE COUNTY. 



vast g*orges by slow almost and imperceptible steps, 

 frost and heat being- no mean assistants in the work. 

 We doubt if one of these canons has been 3,000 years 

 in cutting-. Let any one who doubts this estimate, or 

 wants more time for the work, visit these g-org-es when 

 the frost is g-oing- out, and observe carefully the condition 

 of the face of the rock, how soft it is, and how much 

 of it is dropping- away, and he will not believe that it 

 has taken countless ag-es to cut these canons out, 

 nor will he ever ag-ain see on these time-scarred walls 

 records of how hig-h the Illinois once stood ! He will 

 laugh at the idea of a mark on them being- fifty years 

 old. 



Starved Rock and Lover's Leap are g-reat masses 

 of St. Peters sandstone almost detached from the blulf 

 and facing the river, the first with terraced cliffs, the 

 latter, with a nearly vertical w^all. Starved Rock is 

 212x212 feet and about 140 feet above low water, con- 

 nected with the bluff by a low isthmus. Lover's Leap 

 is of the same heig-hth, but long- and narrow, descend- 

 ing- steeply on the side from the river. 



Bailey's Falls, Todd's Ford and Bull Rush Falls 

 all owe their wild pictnresqueness to the fact that the 

 La Salle limestone, some twenty-four feet thick, has near 

 the middle a band of g-reenish, shaly rock which water 

 and frost break up and cause to crumble away. Thus 

 the upper layer of limestone, a bed twelve-ta fourteen 

 feet thick, rather hard and with few joints, is left un- 

 supported, and when the weight of the overhang-ing- 

 shelf or 1able becomes great enough to break it off, or 

 a joint is reached it falls, usu'^lly taking- a more or less 

 inclined position, sometimes falling on edg-e, sometimes 

 sliding several feet. Some of these masses at Bailey's 

 Falls are of immense size, one being- 51x17x12 feet, and 

 others nearly as large are found there, and many hug-e 



