OUTLINES OF FIELD-GEOLOGY I-ART i 



the same in both, but differ < . ,ly in direction. A 



geologist trusting to the map A inserts the boundary-lines 



<-n the formations i, 2, 3. 4, juiding hi: 





Fie. 3. Maps showing the effect of incorrect topography in distorting geological 

 lines. 



by the points of intersection of the different streams. If 

 now he were to trace these same lines on a map with the 

 correct topography, as shown in li, he would find them to 

 present considerable differences from those on A, although 



