PUBLIC PARKS OF IOWA 41 



PURCHASED OR CONSIDERED AREAS. 



REPORT OF THE BACKBONE AREA. 

 By L. H. Pammel, Botanist. 



The Devil's Backbone, in Delaware County in northeastern Iowa, has 

 become somewhat famous because of the geologic investigations made 

 by McGee in his exhaustive memoir on the Pleistocene history of north- 

 eastern Iowa. (Rep. U. S. Geological Survey, 1891:189-577). The 

 earlier work of David Dale Owen in 1839 who made a (Rep. of the 

 Geological Exploration of part of Iowa, Wisconsin and Minnesota, 1844) 

 report on the mineral lands, soils, timber and rock. Many years later 

 the lamented Dr. S. Calvin made an investigation of the unique topography, 

 geology and fossils of the region. (Iowa Geo. Survey 8:121-192). Dr. 

 Calvin in describing this region says: 



"The region in Richland township includes the somewhat noted locality 

 known as 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. Erosion and secular de- 

 cay 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. 

 center of section 16 and Forestville, and southward along the river to 

 section 34, constitute a region of loess-Kansan topography." 



The deep valleys of the Richland highland as well as the similar 

 valley of the north Maquoketa resemble canyons of pre-glacial origin. 



There is no drift, at least there is none of lowan age. The exposures 

 occur on hills through which the Maquoketa flows in a gorge 200 feet in 

 depth. The hills rise eighty to one hundred feet above the adjacent por- 

 tions of the lowan drift plain, and the region is one of many that give very 

 positive indications of the fact that in Delaware county the lowan ioe 

 did not overflow eminences that rose a few score of feet above the gen- 

 eral level. The region is rich in fossils, Dr. Calvin says: "At the 

 Backbone, in section 16 of Richland township, the vertical cliffs, eighty to 

 ninety feet in height, show the following section: 



Feet 



4. Pentamerus beds, massive and weathering irregularly 25 



3. Band of chert, with casts of Pentamerus 1 



2. Pentamerus beds, like No. 4 43 



1. Massive beds, without Pentamerus, but containing colonies of 



Halysites catenulatus and Syringopora tenella 20" 



Some fifty kinds of fossils have been found in this region. 

 L . 



