I 



PROCEEDINGS OF THE AMHERST MEETING 



to the model left each of the dowel sticks long enough so that it could be 

 pushed into proper position and into a gimlet-hole in the wooden base on 

 which the model was constructed. The same color was made use of for 

 the same geological formation or the same phase of the formation, both 

 on the celluloid sheets and the dowel stick. Moreover, the vertical scale 

 of the model was kept the same as the horizontal scale. When complete 

 the model enabled one to see things exactly as they existed in the mine 

 and to project downward the geological relations in such a manner as to 

 prophesy definitely what might be encountered at depth. Models of this 

 kind are expensive and entail much work, but if money were available a 

 few should be made for use in courses in economic geology. 



Figure 15. — Example of a relatively inexpensive Exhibition useful in Teaching 



In this connection attention should be called to the desirability of ar- 

 ranging inexpensive but helpful study exhibitions, such as that shown in 



figure 15. 



SUGGESTED GEOLOGICAL MODELS 



Among others, the following geological models could be used to advan- 

 tage in the class-room and laboratory if made of suitable size : 



1. Two or more models of east- west Appalachian sections, with a de- 

 tachable cap showing the parts removed by erosion. One, for example, 

 from Harrisburg to Tyrone, and one or more across the southern Appa- 

 lachians, where thrust faulting is strikingly shown. In other words, sec- 

 tions of mountains of what E. T. Chamberlain calls the "thin-shelled" 

 type. 



