70 W. M. Davis — Geographic Teaching. 



is simply an iinconsumed remnant of the greflter mass of un- 

 known dimensions and form, from which the old lowland was 

 carved. When the lowland was uplifted, Monadnock and its 

 fellows were raised with it. In my teaching, Monadnock has 

 come to be recognized as an example of a distinct group of forms, 

 and its name is used as having a generic value. A long para- 

 graph of explanation is packed away when describing some other 

 mountain as a " monadnock " of greater or less height. 



The valleys by which the plateau is dissected have all been 

 excavated since the uplift of the old lowland. Where the plateau 

 is high the valleys are sunk deep below it. The Deerfield valley 

 in northwestern Massachusetts is a full thousand feet deep. 

 Where the uplift was small near the coast, the valleys are shallow. 

 Where the rocks are hard, as is generally the case, the valleys 

 are narrow, like that of the Deerfield above named. Where the 

 rocks are soft, the valleys are wider ; illustrating the general 

 principle that mature and old forms are more rapidly developed 

 on soft than on hard rocks. The Berkshire valley, excavated in 

 limestone between crystalline rocks and schists, is six or more 

 miles wide. The Connecticut valley, excavated in weak sand- 

 stones, is even wider, forming a valley loAvland ten or fifteen 

 miles from side to side and broadly dividing the plateau into 

 eastern and western portions. Occasional beds of hard rocks, 

 chiefly ancient lava flows, occur in the sandstone belt, and are 

 much less eroded ; they form ridges rising far above the lowland, 

 and indeed still retain nearly the height of the adjacent plateaus. 

 Mount Holyoke, opposite Northampton, is a type of these 

 ridges. It holds essentially the same relation to the lowland 

 that Monadnock holds to the plateau. Both are residual 

 mountains of harder rocks; but the two manifestly belong to 

 different generations of geographical development. 



It appears from this brief outline that our New England geog- 

 raphy is of composite quality. The uplands with their residual 

 mountains re})resent the closing stages of one generation or 

 " cycle " of development ; the valleys represent the more or less 

 advanced beginning of another cycle. The distribution of our 

 villages and our occupations, the lines of travel, and the move- 

 ments of population may all be shoAvn to depend largely on the 

 topographic forms thus classified. 



By following some plan of treatment such as this, it becomes 

 possible to make just comparisons between different regions— 



