CHAPTER Lin. 



SUGGESTIONS AS TO LINES OF STUDY. 



THE first and perhaps the most important work to do in be- 

 ginning the study of the geology of any locality is topographic. 

 The topography of a place includes its actual location, its rela- 

 tive position as to mountains, hills, valleys and plains; as to 

 lakes, ponds, swamps, marshes, rivers and other streams. It 

 also includes a study of the soil and vegetation, and as these and 

 other topographic features depend largely on climatic conditions, 

 temperature, winds and rainfall need to be considered in topo- 

 graphic work. 



This work is not only an important introduction to geological 

 investigation, but the items considered in topography constitute 

 the environment of the various forms of life, and need to be un- 

 derstood and considered in any good botanical or zoological 

 work. Topographic work is not only important, but easy and 

 interesting. 



Actual location is readily ascertained in all those states where 

 the rectangular system of survey was used. Under this system 

 principal meridians were located with great accuracy, and the 

 country on each side was divided into ranges six miles wide by 

 secondary meridians, as nearly parallel with the primary merid- 

 ian as the spherical form of the earth would permit. The first 

 principal meridian is the boundary between Ohio and Indiana in 

 longitude 84 51' west; the second runs through Indiana in 

 longitnde 86 28' west; the third through Illinois in longitude 

 89 10' 30" west; the fourth is in longitude 90 29' 56" west,- 

 the fifth is in longitude 90 58' west; the sixth in longitude 97 

 22' west, and the Michigan meridian in longitude 84 19' 9 // 

 west. Others were located as occasion required. A base line 

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