STRATIGRAPHIC CLASSIFICATION 143 
development of a camp has reached a_ stage where these ques- 
tions arise, no map can be too detailed to be serviceable. In 
making such a map all available facts bearing on the original 
condition of the rocks and the subsequent changes they have 
undergone should be shown as far as possible. 
H. Foster Bain. 
IDAHO SPRINGS, COL., 
February 17, 1902. 
