328 



EARTH FEATURES AND THEIR MEANING 



Just as the " parallel roads " of Glen Roy, roads in name only, 

 are the beaches of earlier glacial lake stages, so in Lake Agassiz 

 we have parallel beaches of the barrier type which are often roads 

 in fact as well as in name, and which mark the stages of successive 

 lakes within this vast basin. The Herman beach, corresponding 

 to the highest level of the lake, is thus a sharp topographic bound- 

 ary between lake deposits and morainal accumulations, and is 



FIG. 357. Portion of the Herman quadrangle of Minnesota, showing the position 

 of the Herman beach on the shore of the former Lake Agassiz. The lake basin is 

 to the left, and the pitted morainal deposits appear to the right (U. S. G. S.). 



further itself a well-marked topographic feature composed of wave- 

 washed and hence well -drained materials (Fig. 357). Farmers of 

 the district have been quick to realize that these level and slightly 

 elevated ridges lack the clay which would render them muddy in 

 the wet seasons, and are thus ideally adapted for roads. They 

 have in many sections been thus used over long stretches and are 

 known as the " ridge roads." 



