PUBLIC PARKS OF IOWA 273 



terest and value. Entirely aside from their aesthetic value all of these 

 areas are of importance to the geologist because of the illustrations of 

 natural phenomena which they furnish, and for that reason as well as for 

 others they are eminently worthy of care and preservation. 



In the great central plains area of the state there are a num'ber of 

 very charming spots, which are all the more noteworthy because of their 

 prairie surroundings. Such are the picturesque valleys of Willow and 

 Lime creeks at Mason City, where the streams have cut the limestone 

 bedrock into steep bluffs and precipices which now are margined and 

 covered with forest growth. On a still larger scale is the gorge of Iowa 

 river at Iowa Falls. Here the river has been displaced in recent geologic 

 times and has been forced to cut a new channel through seventy feet 

 of solid limestone. Several small tributaries have had to undergo the 

 same treatment and the result is a series of gorges and retreats which 

 give the region a rare beauty and rugged charm. The older channel of 

 the river is said to be still discernable to the south of the present one. 



Steamboat Rock is another locality of geological and general interest 

 and there are several others along the Iowa, such as the stretch above 

 Iowa City, which owes its rugged character to the vagaries of glacial 

 occupation. The older rocky hills were buried with the drift and when 

 the river, whose location was determined by the topography of the gla- 

 cial 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 Estherville, at 

 Fort Dodge, the high bluffs above Boone, and the delightful "ledges" below 

 that city, the Red Rock bluffs at the village of the same name, the charm- 

 ing bluffs at Cliffland below Ottumwa, and the numerous points of in- 

 terest about Keosauqua. There is no spot in central Iowa which offers 

 better natural facilities for a beautiful park than the area on either side 

 of the river midway between Boone and Fraser. The entire 200 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 little valley, while trees rise to the summits of the 

 bluffs and form a setting for an exceedingly charming scene. The bluffs 

 near Red Rock and Clrffland are also cut in sandstone of Coal Measures 

 age and are of interest because of their geologic history as well as for 

 their natural beauty. 



I have already spoken of the great ice sheets and of their glacial de- 

 posits as effacers of those types of topography which are due to erosion. 

 It is partly because of this fact that the western two-thirds of Iowa has 

 so few rock outcrops and hence relatively few spots of charm and beauty. 

 Aside from a few localities and those chiefly along the larger streams, 

 the work of erosion since the retreat of the ice sheets has been confined 

 to the glacial drift deposits, which while easily eroded give rise to the 

 softer, more subdued types of landscape. 



But there is a peculiar type of topography which is intimately asso- 

 ciated with the depositional work of the last, the Wisconsin glacier, with 



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