840 THE JOURNAL OF GEOLOGY. 



have a topography of moderate relief and gentle profiles. But 

 this is more characteristic of the unstratified than of the stratified 

 phase. Either phase may have a rough topography, rough 

 rather by virtue of the small size, steep slopes, and close juxta- 

 position of the elevations and depressions, than because of great 

 relief. Extreme roughness of drift topography is perhaps as 

 characteristic of certain special phases of stratified drift as of 

 unstratified, but it is more characteristic of intimate associations 

 of stratified and unstratified drift than of either alone. 



If the average thickness of the drift be no more than one 

 hundred feet, the average amount of relief for which it can be 

 responsible is manifestly not great. The greater its thickness, 

 the greater the variations of surface which it can produce, if 

 irregularly disposed. Reliefs of one hundred feet or so, attrib- 

 utable to the drift alone, are not rare along certain belts of thick 

 drift. Such differences in altitude may occur within the space 

 of a few rods, but they do not characterize any considerable 

 fraction of the drift-covered area. Reliefs of much greater 

 range, belonging wholly to the drift, are seldom met with. 

 Where so great relief occurs within narrow geographic limits, 

 it is usually where deep, abrupt, kettle-like depressions are 

 associated with equally abrupt hillocks. 



The topography of the drift is not defined or described when 

 its range of relief is indicated. Nothing more need be said con- 

 cerning it at this point, than to indicate that one of its notable 

 characteristics is the presence of multitudes of depressions which 

 have no surface outlet. These depressions may have any depth 

 up to a hundred feet or more. Reference is here made only 

 to those depressions which affect the surface of drift, not to 

 those for whose existence the irregularities of the surface of the 

 underlying rock is largely or wholly responsible. 



The depressions may be of any form, regular or irregular. 

 They may be of any area, up to many square miles. Their 

 slopes may have any degree of steepness, limited only by the 

 angle at which loose material like the drift will lie. They may 

 be closely grouped or widely scattered. Thousands and tens of 



