of this animal are abundant in Illinois rocks, but 

 complete specimens are rare. 



6. PREHISTORIC SEA ANIMALS. Illinois was 

 covered by seas many times as evidenced by these 

 marine fossils found in Illinois. 



7. ELEMENTS ARE THE BASIC CHEMICAL 

 SUBSTANCES OF THE UNIVERSE. An exhibit 

 showing elements as the raw material on which we 

 build our modern civilization. 



8. PLANTS AND ANEVIALS FROM THE COAL 

 AGE FOREST SWAMPS OF ILLINOIS. Part of the 

 Museum's extensive collection of Mazon Creek con- 

 cretions containing fossil remains of worms, crayfish, 

 insects, clams and plants. These are found in beds 

 of clay and in shale associated with the great coal 

 deposits of Illinois. 



9. ILLINOIS FORESTS OF 250,000,000 YEARS 

 AGO. Fossils from shale associated with our coal 

 fields are exhibited here. Plants such as these were 

 the raw materials from which coal has developed. 



The Geology Room also contains other extensive 

 collections of rocks and minerals, fossils, crystals 

 and commercial building stone. 



10. SPECIAL MINERAL EXHIBITS. (Between 

 Main Hall and West Corridor) Two very interesting 

 exhibits are situated across from each other. One, 

 a collection of minerals possessing the property of 

 fluorescing with brilliant colors under ultra-violet 

 or * 'black light," may be controlled by the observer. 

 The second, which consists of a Geiger Counter de- 

 vice placed beside a movable turntable, contains 

 minerals of varying radioactivity. The audible tick- 

 ing and visual blinking light indicate the amount of 

 radiation given off by each mineral. 



