Wisco7ism Kettle Moraine. 203 



form of a funnel, or of an inverted bell, while the shallow ones 

 are mere saucer-like hollows, and others are rudely oval, oblong, 

 elliptical, or are extended into trough-like, or even winding hol- 

 lows, while irregular departures from all these forms are most 

 common. In depth, these cavities vary from the merest indenta- 

 tion of the surface to bowls sixty feet or more deep, while in the 

 irregular forms the descent is not unfrequently one hundred feet 

 or more. The slope of the sides varies greatly, but in the deeper 

 ones it very often reaches an angle of 30° or 35° with the horizon, 

 or, in other words, is about as steep as the material will lie. In 

 horizontal dimensions, those that are popularly recognized as 

 "kettles" seldom exceed 500 feet in diameter, but, structurally 

 considered, they cannot be limited to this dimension, and it may 

 be difficult to assign definite limits to them. One of the peculiar- 

 ities of the range is the large number of small lakes, without inlet 

 or outlet, that dot its course. Some of these are mere ponds of 

 water at the bottom of typical kettles, and, from this, they gradu- 

 ate by imperceptible degrees into lakes of two or three miles in 

 diameter. These are simply kettles on a large scale. 



Next to the depressions themselves, the most striking feature of 

 this singular formation is their counterpart in the form of rounded 

 hills and hillocks, that may, not inaptly, be styled inverted ket- 

 tles. These give to the surface an irregularity'' sometimes fittingly 

 designated " knobby drift." The trough-like, winding hollows 

 have their correlatives in sharp serpentine ridges. The combined 

 effect of these elevations and depressions is to give to the surface 

 an entirely distinctive characier. 



These features may be regarded, however, as subordinate ele- 

 ments of the main range, since these hillocks and hollows are 

 variously distributed over its surface. They are usually most 

 abundant upon the more abrupt face of the range, but occur, in 

 greater or less degree, on all sides of it, and in various situations. 

 Not unfrequently, they occur distributed over comparatively level 

 areas, adjacent to the range. Sometimes the kettles prevail in the 

 valleys, the adjacent ridges being free from them ; and, again, the 

 reverse is the case, or they are promiscuously distributed over 

 both. These facts are important in considering the question of 

 their origin. 



