SOME GEOLOGIC ASPECTS OF CONSERVATION 143 
with drift and when the river, whose location was determined 
by the topography of the glacial deposits, cut through these to 
the rock, it must perforce maintain its course and so was obliged 
to cut deeper and deeper into the massive limestones which lay 
athwart its path. 
Along the Des Moines are many beautiful spots, as at Esther- 
ville, at Fort Dodge, the high bluffs above Boone, and the de- 
lightful “Ledges” below that city, the Red Rock bluffs at the 
village of the same name, the charming bluffs at Cliffland below 
Ottumwa, and the numerous points of interest about Keosauqua. 
There is no spot in central Iowa which offers better natural fa- 
cilities for a beautiful park than the area on either side of the 
river midway between Boone and Fraser. The entire two hun- 
dred feet of the valley’s depth shows only glacial drift, and in 
places the slopes rise from the water ’s edge in a single sweep 
and are wooded from base to summit. Of an entirely different 
sort is “The Ledges.” Solid sandstone walls rise sheer from the 
water and even overhang in places, a carpet of verdure covers 
the floor of the little valley, while trees rise to the summits of 
