142 PUBLIC PARKS OF IOWA 



delightful touch of green even in the midst of the winter's snows. Across 

 the river there rises from the water's edge a great massive battlement of 

 rock which adds its changeless beauty and grandeur to the whole delight- 

 ful assemblage of attractions. 



Dr. Calvin states in his description of the geology of the county that 

 Cedar river has evidently had a long and changeful history. Its valley 

 owes its size and rugged character largely to preglacial, or at any rate 

 to pre-Kansan erosion. It was formed before the lowan ice-sheet, the last 

 to invade this region, came down and tilled it with ice. I can do no bet- 

 ter here than to quote from Doctor Calvin's report on Mitchell county, 

 where he says: "There has been no permanent filling of the valley with 

 drift. In type this waterway is allied to the waterways of the Driftless 

 Area. There are the original precipitous rocky cliffs rising vertically from 

 sixty to eighty feet and the total depth below the level of the upland 

 plain ranges from ninety to 120 feet. The sides of the Cedar river val- 

 ley are cut by deep erosion trenches, recalling the topography of the 

 Driftless Area, or areas of thin Kansan drift; and the tributaries, few 

 and insignificant though they are, enter the main stream through rock 

 cut troughs and gorges." 



Another remarkable feature of the region bordering the river west of 

 Osage is the fact that although most of the region is covered with drift 

 from the lowan glacier, there rise out of it and above the general level, 

 what Doctor Calvin called loess islands. These are tracts which the 

 lowan ice either did not cover or on which it failed to leave any coating 

 of clay and other debris which it carried. Hence the older topography 

 and materials of the Kansan plain remain, mantled only by a thin veneer 

 of loess, a fine dustlike material blown hither from the lowan drift plain 

 very soon after this was uncovered by the melting of the ice. Thus we 

 have here a typical example of the topography and surface mantle of a 

 region which is vastly older and more mature than are those of the lowan 

 region. This older topography, that of the Kansan drift, once covered all 

 of Iowa except the strip in the northeast known as the Driftless Area. But 

 it has since been overridden in the northcentral portions from Winne- 

 shiek to Osceola counties by later glaciers and its characters have been 

 more or less completely masked. This Osage loess island, therefore, 

 takes on added interest both because of its proximity to the picturesque 

 features of Cedar Valley and of its typical display of characters which 

 are related to the Kansan drift region of Winneshiek county and the coun- 

 ties farther south. 



FLORA OF MITCHELL COUNTY. 

 By Flora Mae Tuttle. 



From the time that I opened my eyes on the beauties of our glorious 

 prairies, down in that little log cabin in Delaware county, I have been 

 deeply interested in the flora of our state. Years ago the unbroken 

 prairies were one gorgeous flower garden. The wild lily, the painted cup, 

 fireweed, ironweed, blazing star, vied with the golden glory of the sun- 



