THE GEOLOGIST AWHEEL. 515 



THE GEOLOGIST AWHEEL. 



By Professor WILLIAM H. HOBBS, 



UNIVERSITY OF WISCONSIN. 



IN no country of the world does the government distribute to its peo- 

 ple with so lavish a hand as in our own the published results of 

 scientific investigation. One example among many that might be given 

 is furnished by the reports of the United States Geological Survey, 

 which for abundance of material, for scientific value and for beauty of 

 illustration are not approached by the geological publications of any 

 European state. Of the many who see the beautifully colored geological 

 maps which accompany these magnificent reports, or the only less elabo- 

 rate and expensive maps prepared by certain of the individual States, 

 doubtless few have the faintest notion of the studies on which they are 

 based. 



No comprehensive study can be made of the geology of any region 

 until some sort of geographical map of the region makes it possible to 

 represent the exposed rock masses in approximately their true positions 

 relative to one another. If the geology be other than of the very sim- 

 plest character — and this will generally be true of mountainous regions 

 — it is not only necessary to fix the geographical positions of rock masses, 

 but their elevations as well. In other words, the map must not only be 

 a plan, but special elevations must be represented, known as geological 

 sections. The most satisfactory representation — and this will be essen- 

 tial for all difficult areas — will be one which shows not only special ele- 

 vations, but the topographic relief of every point in the area. A proper 

 preparation for detailed geological work in a difficult area involves, 

 therefore, the making of a relief or topographic map based on correct 

 triangrdation, and of a scale and an accuracy of delineation of relief 

 forms commensurate with the complexity of the geological structure. 

 For large areas of the eastern United States such maps have been prepared 

 by the United States Government, sometimes in cooperation with the 

 State governments, and these maps maybe obtained in the form of beau- 

 tifully engraved atlas sheets by any one and at merely nominal prices. 

 On these maps are shown in black the railroads, highways, houses, etc. 

 (the culture); in blue, the lakes, streams, swampy areas, etc. (the hydrog- 

 raphy); and in brown, the lines of approximately equal altitude (the 

 topography). 



With such a map the field geologist can begin intelligently his geo- 

 logical work. This work will consist first of all in the collecting of his 



