Frank Oramer — Recent Rook Flexure, 22o 



which it was placed when the mill was built, all point to the 

 same cause. These different lines of evidence arc inseparably 

 connected, and taken together amount t<> ;) demonstration that 



the rock under the mill suffered an uplift. The effect on the 

 artesian well proves that the area of disturbance was not con- 

 fined to the mill; and the parallel fractures out in the river 



bed show that similar movements have occurred before. The 



irresistible conclusion is that a movement in the rock was pro- 

 duced by lateral thrust under the very eves of men. 



There can be little doubt that the building of the mill pro- 

 vided the occasion for the movement in the rock. Not only 

 was a great mass of water held up by the new dam, and con- 

 siderable earth removed in the building of the mill, but in 

 getting <»nr Btone for the dam and mill two quarries, each 

 oral feet dec}), were made in the river bed, one above the 

 dam and the other below the mill. The axis of the disturb- 

 ances in and under the mill runs from one quarry to the other ; 

 and this fact indicates that the break occurred along a line 

 whose weakness was at least partly determined by recent 

 change 



The Fox River Valley is an almost perfectly level clay plain, 

 cut by deep ravines that run back to varying distances from 

 the river and form the drainage system of the plain. The 

 river has cut its way through the clay and flows on a rock 

 bottom between banks from 60 to 90 feet high. The rock 

 underlying the plain is therefore subjected to a very great 

 and uniform pressure, over an area extending back several 

 miles from the river. The river makes two bends at the point 

 where the mill is located, and the two lines of fracture and 

 crushed rock out in the river, and the line of disturbance in 

 and under the mill are parallel with each other and with the 

 course of the river between the two bends. This parallelism 

 is suggestive, and would be in harmony with the theory that 

 the phenomena were due to lateral pressure in the river-bed 

 induced by pressure of the overlying clay on the adjacent rock. 

 But other phenomena, which have been observed in the neigh- 

 borhood, preclude the adoption of this theory as an explana- 

 tion. 



At Kaukauna, about two miles down the river from the 

 Combined Locks, Col. H. A. Frambach built a paper mill some 

 time ago. The work of cutting a tail-race in the rock was 

 facilitated by the presence of two joints 30 feet apart. These 

 joints, whose direction was nearly at right angles to the course 

 of the river, converged slightly shoreward and passed down- 

 ward to an unknown depth. The perpendicular faces were in 

 •close contact in both seams; and the strata between the two 

 seams were slightly bowed up in the middle (a, fig. 4). 



