PUBLIC PARKS OF IOWA 47 



Might I suggest that during the summer plans should be made for a 

 road leading "to the park from the Lamont and Manchester side of the 

 park; also that before next summer we should make arrangements with 

 Professor G. B. MacDonald to reforest the depleted area with native 

 species. I noticed in some places young white pines are coming up, 

 showing that when given a cha,nce native species will recover the ground. 



GEOLOGY OF DELAWARE COUNTY. 

 By Samuel Calvin, Geologist. 



Inside the lowan area, and surrounded on all sides by lowan drift, are 

 two anomalous regions that seem not to have been invaded by lowan ice. 

 One of the regions occupies the central part of Richland township and 

 may be called the Richland highlands. The other embraces three-fourths 

 of Delhi township, and parts of Milo, North Fork, South Fork and Union 

 townships and may for convenience of reference be named the Delhi 

 plateau. The regions in question seem to have been islands in the 

 midst of the lowan glacial sea. At all events they contain no lowan drift. 

 The topography is erosional, partly resembling the loess Kansan type, 

 partly that of the driftless area. Except in the stream valleys the sur- 

 face is on the average higher than that of the lowan drift plain, the dif- 

 ference in elevation ranging from forty to more than a hundred feet. 

 Both areas are traversed by the Maquoketa river. In each there are heavy 

 bodies of loess exhibiting the rounded hills, steep slopes and sharp val- 

 leys that result from erosion of this peculiar deposit. In each there 

 are spaces, free from both loess and drift, in which steep rocky cliffs, isolated 

 towers, and all other features of driftless area topography are character- 

 istically developed. 



The region in Richland township includes the somewhat noted locality, 

 the "Backbone." The "Backbone" is a high rocky ridge around which 

 the Maquoketa forms a loop. The summit of the ridge rises from 90 to 

 140 feet above the stream. Its sides are in places precipitous, the rocky 

 cliffs rising sheer for more than 80 feet. Erosin and secular decay have 

 carved the rocks into picturesque columns, towers, castles, battlements 

 and flying buttresses. The exposed surfaces are deeply pitted and 

 weather worn. Crevices, widened by protracted chemical action of air 

 and water, are wholly or partly filled with dark brown residual clay or 

 geest. The stream, on each side of the ridge, flows in a deep valley. The 

 "Backbone" with its valleys on the east and west is a bit of Driftless 

 area, and the sections north of the "Backbone," namely 3, 4, 5, 8, 9 and 10, 

 as well as the region to the southeast between the centre of section 16 

 and Forestville, and southward along the river to section 34, constitute 

 a region of loess Kansan topography. 



Between the south end of the area just described and the southeast 

 quarter of section 4 of Milo township, the Maquoketa flows through the 

 lowan drift plain, in a valley but little depressed below the general level 

 of the country. In the northern part of Milo township, the river enters 

 the second of the anomalous areas, and in doing so it turns away from 

 a low drift plain to cleave its way through an area that rises from eighty 

 to a hundred feet higher than that from which it turned aside. These 



