PUBLIC PARKS OP IOWA 119 



"By reason of their relatively greater refractoriness, they often project 

 beyond the softer matrices, and closely simulate the trunks of trees, and 

 they are currently known as such. To make the delusion more complete 

 the pressed cylinders weather concentrically and have a striking re- 

 semblance to the truncated bodies of exogenous trees of gigantic propor- 

 tions. The lower bed of the section 'shows in many places cross-bedding, 

 the appearance of which is intensified by the differential corrasive and 

 corrosive effects of the present stream. The sandstone is known to have 

 a thickness of upwards of one hundred feet and has been represented in 

 the section as occurring in three stages. The divisions are arbitrary 

 rather than real; the external differences being due to accidents of 

 weathering rather than to variable conditions during sedimentation. 



"The ledge sandstones may be considered as a geological unit repre- 

 senting a period of continuous deposition. As in most deposits of its 

 kind it is of limited extent. It thins out rapidly both to the north and 

 south. At Bear creek half a mile down the river it is reduced to forty 

 feet, and two miles in either direction from its typical exposure it entirely 

 loses its identity, giving place to alternating sands and shales. One mile 

 and a half toward the source of Peese creek the older measures pass un- 

 conformably under the ledge sandstone. Approaching from the south 

 about one mile below the mouth of the Bear, two seams of coal are easily 

 seen outcropping along the river bank, the lower being twenty feet above 

 the water. 



"Where first observed these coal beds are separated by a considerable 

 thickness of shale and clay. Proceeding northward the intervening strata 

 gradually disappear, and before reaching the mouth of the creek the veins 

 themselves end abruptly, and the ledge sandstone comes into view. Both 

 stratigraphically and lithologically the ledge sandstone seems to have its 

 homologue in the massive sandstone exposed in Marion county and cur- 

 rently known as the Redrock sandstone." 



The Redrock standstone is indicative of a considerable oscillation of 

 the shore line during carboniferous times, by which the land in that vicin- 

 ity was elevated, profoundly eroded and then submerged by the gradual 

 tilting of the surface on an axis more or less parallel to the shore line. 

 This was a period of vigorous erosion on land and of rapid Sedimentation 

 in the area in question. The ledge sandstone was laid down during this 

 time and was followed by re-elevation. 



To those who have the "wanderlust" a day spent at the Ledges Park 

 will satisfy the "call of the wild" that comes to us all at times. To the 

 writer The Ledges are Nature's Book of Knowledge my friends, the 

 birds, are always here to welcome me and it seems that their song 

 sounds sweeter there than anywhere else in Iowa. 



The study of bird life is at all times an interesting -theme and many a 

 pleasant hour may be spent in woods and fields observing our feathered 

 friends in their native haunts. For upwards of twenty-five years the 

 writer has taken an interest in our birds and studied their life histories- 

 simply for love of the work. Happy hours have been spent in the fields 

 and woods greeting our sojourners from the sunny south and taking notes 

 on their everyday life their song, their nesting and food habits, field 

 notes that are full of the sunshine of summer days, the singing of birds, 



