STATE HORTICULTUR7VL SOCIETY. 121 



SECOND DAY— EVENING SESSION. 



THE SOILS OF NORTHERN ILLINOIS. 

 [By James Shaw, of Mount Carroll.] 



Gentlemen of tlie Illinois State Eortimdtural Society: 



I find myself a member of your Committee on the Geology of Soils; and by request 

 of your worthy President I propose to occupy your attention a short time in discussing 

 the soils of Xorthern Illinois, and the dynamical forces which have originated, trans- 

 ported, and mingled these soils, clays, and superincumbent masses covering the bed 

 rocks. 



Your Secretary, in classifying the fruit districts of the State, maps out one as the 

 Rock River District. My remarks 011 this occasion will apply principally to that 

 district. You will hear from my co-laborer to-morrow as to the soils of Southern 

 Illinois. I shall not conrtue myself strictly to the Rock River Valley, but shall speak 

 of that p;u-t of our State lying north of the old Silurian Beach, which crosses the State 

 from a point near Hampton on the Mississippi river, and passes eastward a few miles 

 south of this place, bending up a little north of Morris, and thence passing on to the 

 eastern line of the State, south of Chicago. Tlio land north of this Silurian Beach was 

 comparatively elevated table land at the time the coal deposits of the great coal basin 

 lying south of this old beach were in process of formation. And there is evidence that 

 over this comparatively elevated tabic land a great denudation has taken place. Some 

 great force has worn ofl and swept away, from Southern Wisconsin and Northern 

 Illinois, a large amount of material, which has been deposited over the face of the 

 country south and west of that elevated region. It is estimated by Prof. Whitney, and 

 other good geological authorities, that at least three hundred feet has been denuded 

 and carried away in the region of the Illinois and Wisconsin mounds. These mounds — 

 Scales Mound, the Blue Mounds, Terrapin Ridge, and the various elevated and island- 

 like elevations left over the general level surfoce of that part of the Slate north of this 

 old Silurian Beach— are monuments left standing when the rest of the formation was 

 swept away. Any one with thoughtful mind, who stands upon their tops and looks 

 over the surrounding country, or who examines the regular succession of outcrops up 

 their sloping sides, cannot resist the conclusion that the general level of the wliole 

 country surrounding once corresponded with these highest points. As in reading a 

 book we at once miss the pages which are torn out, so in examining these mounds, 

 we at once miss whole leaves and parts of leaves in the Great Stone Book, which have 

 been removed by the forces of which I shall presently speak. The Galena Lime- 

 stone, the Cincinnati Group, and the Niagara Limestone, are the leaves, whose frag- 

 ments yet remain to attest a time when each one of them in regular succession spread 

 over the region now under discussion. 



Against this Silurian Beach of which I have spoken, the coal meSsui'es are shingled, 

 as it were, or deposited. At the place where we are now assembled, the old St. 

 Peter's sand.stone shines like sugary masses along the river banks, and is elevated in 



