4 BOTANY OF L,A SAL,LE COUNTY. 



IX and X, or representatives of them, are found 

 within our territory, and II, VII and VIII are 

 mined; III is a double bed, twenty inches of coal, each 

 bed ten inches thick; IV is a bed of poor coal; VII, 

 the great Streator bed; VIII is found in Deer Park 

 township and at L/a Salle, aud IX and X are shales; 



X a very thin poor cool found about Iva SaHe; V is a 

 black slate. Coals III and IV about one-third the 

 way from Stteator to lya Salle change to black slates, 

 and are found . every where in the banks of streams, 

 and in borings. They are remarkable for their regu- 

 lar thickness and for splitting int6 large thin sheets. 

 Bed VI is represented by shales more or less bitumi- 

 nous. The coal measures are made up of beds of fire 

 clays, shales or clay slates; of various colors, sand- 

 stones, generally soft, often highly charged with 

 bisulphide of iron (pyrite, fool's gold, sulphur, &c.) 

 which, decomposing in the presence of moisture and 

 air, causes the rock to crumble and renders it useless 

 for any purpose. This is not always the case how- 

 ever, there being some of these sandstones which 

 withstand the atmospheric agencies and are not splii 

 up 1 ^ frost, 



The coal measures also contain in the west part of 

 our 'field, thick beds of magnesian' limestone as well 

 as Some thin ones of argillaceous and some of highly 

 arenacous limestones, but they are of limited extent 

 and local importance as surface rocks. '. yl 



Resting? on the coal, measures we find what seems at 

 fist sight a, confused mass of clays, sands and g-ravels 

 and of .almost eyery possible combination of them with 

 here and there considerable masses of rock^ and these 

 such as are not found here in beds, and they are 

 always more or less rounded, sometimes very smooth.' 

 The gravel is very largely limestone and as most pieces 



