144 GEOLOGY OF ILLINOIS. 



inches to the mile. Besides this the abrupt, rocky hills approach closer 

 to either bank of the river as it now runs ; and there is nothing about 

 it between these two points, having any resemblance to the usual al- 

 luvial bottom now under consideration. For some cause the Father of 

 Waters left its old channel and broke through the rocky hills, gaining 

 twenty miles in distance and leaving the upper rapids as the result.* 

 ' But leaving this interesting question I will refer to the other parts of 

 the county, where the alluvium is prominent. In the south-eastern 

 part of the county, the townships of Montgomery, Hahnaman, Tampico, 

 Hume, and Prophetstown, are largely made up of wet or swamp lands. 

 Peaty marshes and sloughs intersect the level face of the country. The 

 soil is deep, black, and water-soaked. The famous Green river Winrie- 

 bago swamp extends across the town of Hahnaman in a somewhat 

 diagonal direction. This swamp is a wilderness of reeds, sedges, and 

 miry sloughs, in which countless thousands of wild geese, ducks, swans, 

 and other aquatic birds, in proper seasons congregate and find an al- 

 most Arctic isolation. 



At almost any of these localities the origin and formation of the 

 prairies is well illustrated. The high land round the swamps, aided by 

 a vast yearly decaying vegetation, is encroaching upon the marshes and 

 building them up into dryer prairie laud. But the county of Whiteside 

 is reclaiming her swamp lands, by an efficient system of ditching, faster 

 than Nature ever dreamed of doing. Thirteen miles of big ditch are 

 now finished and under contract. Already, hundreds of acres of land, 

 after being drained, have advanced in value from a few cents to many 

 dollars per acre in value. The scheme promises to add greatly to the 

 material wealth of the county. 



The usual dark surface, organic, gem soils of the prairies, .the leaf 

 molds of the groves, the sands and gravels recently deposited by Rock 

 river, and the white soils of the barrens and oak timber tracts, may be 

 said to make up the rest of the alluvial deposits. 



Loess. When the Mississippi occupied the higher of the three beds 

 above referred to, and extended from its eastern to its western line of 

 bluffs, and in many places spread out over the level prairies, the term 

 river was hardly a proper designation for the great sheet of water. It 

 approached more nearly the character of a great lake or inland sea of 

 fresh water, with its surplus water falling over the mountain chain of 



*NoTE. It would seem more probable tbat the ancient river or ocean current, by which the valley 

 now occupied in part by the waters of the Mississippi was excavated, was divided somewhere in the 

 vicinity of Fulton, and that one arm ran through these sloughs into what is uow the valley of Rock 

 river, while the other followed along the present channel of the Mississippi, thus making an island of 

 the northern part of Rock Island county. We have elsewhere attempted to show, in a former volume 

 of these reports, that the valleys now occupied by the Mississippi and the Illinois are older than the 

 drift, and consequently could not have been formed by the existing rivers. For a more full discus- 

 sion of this subject the reader is referred to Vol. 1, page 7, et. seq. A. H. W. 



