DEMONSTRATION MATERIAL IN GEOLOGY 



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longitudinal section of a vertical vein and is condensed from the workings 

 of an actual mine, the Camp Bird, in Colorado. The condensation was 

 accomplished by omitting all but one of any feature that is repeated in 

 the actual mine. The important part of the model is the section which 

 forms its face. Here the vein formation and several types of mine open- 

 ings are shown. The sulphides of the ore are simulated by bronze paint 

 for luster, toned down to the proper colors and luster by transparent 

 washes of oil color. 



b. Another model in the Field Museum is that of a coal mine (figure 

 11) which illustrates the mining as well as the geological occurrence of 

 coal. This model is small, being about two feet square by one foot in 

 height, and the scale is small — 100 feet to the inch. It shows the surface 



Figure 12. — Model of the Mount Greylock {Massachusetts) Syticlinorium 



of a coal mining region in Virginia, with colliery buildings in the rear. 

 At the location of the main shaft the ground is cut away to the level of 

 the roof of the coal bed and a geological section is reproduced on the 

 vertical surface. The front half of the model is at the level of the coal 

 seam and shows the coal and the workings with the roof removed. 



c. A third model shows the relations of the topography of surface to 

 that of the underlying rock in a glaciated region. The surface shows a 

 rolling country, with fields and farm buildings. The front of the model 

 is in the form of a section showing horizontally bedded limestone of the 

 character of that underlying Chicago. 



5. In the American Museum of Natural History, New York City, are 

 a number of excellent geological models, among which is one of the Con- 

 necticut Valley and one of the Copper Queen Mine, Arizona. They are, 

 however, too large for use in the class-room. 



