
GEOLOGICAL MAPS AND SECTIONS 325 
structed, namely, Horizontal or Profile and Vertcal, the 
former being designed to show the form of the ground and 
the geological structure of the region traversed, while the 
latter are meant to exhibit in detail merely the vertical 
succession of the strata. 
Horizontal (Profile) Sections.—If these are to be accurately 
constructed, they must be drawn upon a true scale—that is, 
the vertical and horizontal scales must be the same. The 
young geologist’s first attempts at section drawing should 
eaeretore be on this true or natural scale. If the vertical 
scale be exaggerated, it is obvious that the lines which are 
meant to show the geological structure must be correspondingly _ 
distorted. A glance at the two sections (Figs. 122, 123) will 

FIG. 122.—SECTION ON A TRUE SCALE—THE HORIZONTAL AND VERTICAL 
SCALES BEING THE SAME. 
serve to make this plain. Fig. 122 is drawn on a natural 
scale, and therefore exhibits the actual form of the surface, 
fem@ecne truc dip of the strata: In Fig. 123 we have the 
same section, but in this the vertical is three times greater 

FIG. 123.—SECTION ACROSS SAME AREA AS IN FIG. 122—THE VERTICAL 
BEING THREE TIMES GREATER THAN THE HORIZONTAL SCALE. 
than the horizontal scale—the result being that not only are 
the surface features grossly exaggerated, but the geological 
structure is distorted—the inclination of the strata being 
greatly in excess of the true angle of dip. It is only by 
carefully plotting our sections to exhibit the actual form of 
