194 GEOLOGY OF ILLINOIS. 



345 feet is probably the same as the Carliiiville and Shoal creek bed, 

 which is usually from 210 to 240 feet above the SpriDgfield coal. 



A. H. W. 



Piatt County is bounded on the north by DeWitt and McLean, on 

 the east by Champaign and Douglas, on the south by Moultrie, and on 

 west by Macon and DeWitt counties. It embraces an area of about 436 

 square miles, most of which consists of prairie, 



The prairies of this county are very rich and in a great measure still 

 preserve their native wildness, are beautiful in the summer season, cov- 

 ered with tall grass adorned with many beautiful flowers, among which 

 are the rose, Liatris, (2 sp.) Physostegia Virginiana, Phloxpilosa, Gerar- 

 dia ternuifolia, Lobelia spicata, Lythrum alatum, Echinacea, Gentiana 

 puberula, Veronica Yirginica, Aster sericeus, and several other species of 

 aster; together with coarser plants, including Monarda (horsemint), 

 Solidago (several species), Silphium or rosin weed (3 species), Pedicular is 

 lanceolata, JSryngiwm yucccefolium, Nabalus asper, Eeliantlius (several sp.), 

 Ceanothus, etc. Marshy spots and ponds are often seen, even on the 

 highest prairies, some of them containing living shells of the genus 

 Physa Lym nea and Planorbis, and having on their margin a growth of 

 Lobelia cardinalis, Vemoniafasciculata and Aster carneus. 



Streams. — Willow Branch heads in several large springs If. W. of 

 Bement; one of these on Thomas Davis' land is said to contain sulphur, 

 but if so, the quantity must be very minute, for I could not detect its 

 presence. This spring spreads out into a large grassy marsh. 



The South Fork of Kaskaskia river rises in the south east part of the 

 county, a little east of Bement, runs southwardly for 12 miles and enters 

 Moultrie connty ; along it there is a strip of timber varying from one to 

 two miles in width. The West Fork takes its rise in the south-west and 

 runs southwardly, soon entering Moultrie ; there is but little timber 

 near it, only first a fringe of willows with a few crab apple bushes 

 beyond ; lower down, the thorn {Crataegus) appears, then plum and 

 cherry ; next cherry, plum, pin oak, laurel oak, elm; still further down, 

 elm, red and white oak, hickory and bur oak. 



The largest stream in this county is the North Fork of the Sangamon 

 river, which traverses the county from north-east to south-west, and 

 along its margin are many springs which afford a constant supply of 

 pure water. In the river we found many very pretty molhisks similar 

 to those already enumerated in the adjoining counties. 



Timber and Topography. — Near the Sangamon the hills are low and of 

 easy ascent, the highest not over 45 feet; the neighboring country is 

 not broken, but somewhat hilly for a half mile from the stream. Along 

 the river and Goose creek there are timber belts of about two miles in 



