72 



GEOI^OGY OF IvA COUNTY. 



Dolomite, 716; carboiiite of lime, 54.35; carbonate 

 of mag-nesia, 45.65; much like calcite; cr3^stals, rhom- 

 bohedral; often dark brown, and with curved faces; 

 common in concretions at Covell creek and on Bi^ Ver- 

 million. Much of our limestone is dolomite; that is, it 

 contains a considerable proportion of magnesia. 



Calcite is readily, dissolved in sulphuric acid; dolo- 

 mite slowly, unless powdered and the acid warm. A 

 drop of this acid on calcite produces a foaming- or 

 effervescence; on dolomite the effect is scarcely notice- 

 ble. Both calcite and dolomite often contain iron, 

 earthy matter, sand, and many other substances. 



Siderite, 721; carbonate of iron; carbonic acid, 

 37.9; iron, 69.1; often contains other elements; mas- 

 sive or crystalline; rhombohedral; ash g"ray, yellowish 

 g-ray, etc.; also brown and reddish brown; when 

 scratched, white, brittle. Often in yellow-coated con- 

 cretions which seem to be made up of concentric shells. 

 Common in Coal Measures. 



Mineral coal, 831. A. Caking- or coking- coals, 

 those that run tog-ether in burning-. Coals No. 2 

 and 7. 



B. Non-caking-, those which burn without stick- 

 ing- tog-ether, 



ZOOLOGY. 



The animals of La Salle county. Mammalia — 

 animals feeding- their young- on milk or g-ivnng- them 

 suck. 



The animal life of the county has, of course, 

 underg-one considerable chang-es since th^ first settle- 

 ment. Some animals have disappeared, usually the 

 larg-er and fiercer or more destructive, while others 

 which follow in the footsteps of man have come in. 



Herbivores or Plant-easing Animaes. — 

 Bison or BuEFaeo. — Bos Americans must at one 



