126 Wisconsin Academy of Sciences^ Aris, and Letters. 



by a low degree of heat, working for a long series of years 

 through the moisture in the sandstone, probably aided by the 

 pressure which lifted the ridges. If the latter, the change and 

 elevation of the rock took place at the same time, and both 

 effects were produced with extreme slowness. 



When was the Eidge Eaised ? — Before the glacial epoch. 

 Wm. H. Caniield, Esq., of Baraboo, has found abundant proof s 

 of the movement of glaciers over the rock since it has been 

 metamorphosed. In many places on the elevated portions 

 smoothly polished surfaces of quartz of great extent have been 

 exposed by removing the soil. Before the glacial epoch, there 

 seem to be no data for fixing the time of the elevating and 

 metamorphic action. There has therefore been ample time for 

 metamorphic action of the most extreme slowness. 



Where and How was the Yalley of Devil's Lake 

 Formed ?— At a previous meeting Dr. Lapham, Secretary of 

 the Academy, advanced in a paper the view, that Baraboo 

 river once ran through this valley on its way to the Wis- 

 consin, and was turned from its former course into its present 

 one by glacial drift. If this view is coiTCct, as the facts seem 

 to warrant, this valley may have been made at any time fi'om 

 the Lower Silurian up to the glacial period. It is not neces- 

 sary to introduce any great convulsion. The regularity of the 

 layers would forbid any sudden and violent upheaval and 

 cracldng of the rock. During the slow process of upheaval, a 

 greater extent than the others, perhaps of nearly the present 

 width of the valley, may have been made. The slowly acting 

 agencies of the atmosphere and of water can have widened the 

 fissure and thrown down the great mass of debris which lies 

 on the south of the valley. The valley is about half a mile 

 wide. The sides slope up from 200 to 300 feet, as steep as the 

 large blocks will lie upon each other, and the remaining 

 height is a perpendicular wall cut by vertical fissures into 

 most fantastic shapes, with natural fortifications and castles, 



