GEOLOGY IN EVERYDAY LIFE MANSFIELD 263 



have special advantages not easily duplicated, it remained for the 

 geologist and the engineer jointly to work out methods for overcoming 

 these difficulties. This seems in large measure to have been accom- 

 plished, and the public has much reason to hope that the structures 

 will prove stable when completed. 



Some years ago the Government undertook the project of building 

 a large reservoir in a western valley for the purpose of irrigation 

 storage. The site had been selected after a careful investigation by a 

 well-known consulting engineer, who reported that it had several 

 advantages over competing sites and that the construction involved 

 no special problems. When drilling began for the selection of a dam 

 site, trouble arose from drilling water, which disappeared almost as 

 fast as it could be poured into the drill holes. Geological investiga- 

 tion showed that the ground-water table in the vicinity of the proposed 

 dam site was nearly 100 feet below the surface. The rocks on which 

 the dam was to be seated were porous and fractured lavas, resting on 

 thick but poorly consolidated and porous volcanic ash. The pro- 

 posed dam would surely allow water to flow away beneath and around 

 the dam without providing the desired storage. The site was aban- 

 doned, and the resulting saving to the Government in avoiding the 

 unwise proposed construction was approximately $2,000,000. 



Although the geologist is indispensable in helping to solve problems 

 encountered in great constructional projects, he is even more necessary 

 when it comes to the consideration of the sources of supply and the 

 nature of the mineral substances that enter into any modern con- 

 structional project, great or small. At the time the Boulder Dam 

 was under construction, the technical journals and locally the daily 

 newspapers carried accounts of the enormous quantities of sand and 

 gravel, cement, steel, etc., that were needed and used, and of special 

 types of equipment designed to handle these materials. Similarly, 

 for the other projects, much information of this sort is available. 



Some years ago E. F. Burchard and G. F. Loughlin compiled con- 

 struction data, not published, for the Interior Department, North 

 Building, in Washington, D. C. This is a modern office building, 

 completed for occupation in 1917. It occupies an entire city square. 

 According to Burchard and Loughlin's figures, about 8,000 tons of 

 metals, more than two-thirds of it structural steel, was utilized. 

 Interesting items in this connection are 20 tons of bronze in locks and 

 49 miles of wire used in signalling and lighting but not for telephones. 

 The nonmetallic minerals used total about 82,500 tons. Of this 

 amount more than a third consisted of sand, gravel and crushed stone; 

 clay products, largely hollow tile and building brick, made up another 

 third. Then came Indiana limestone, plaster and cement and a num- 

 ber of others. These materials came from 28 States and 3 foreign 

 countries. 



