(dp) f 
us (bu) 
rement of the inclina- 
sed as bedding traces. 
ly the first of signifi- 
and d. 
ach photograph of the 
ducial marks (fig. 3). 
e point on each photo- 
nt of the other photo- 
ter). 
‘ight-hand photograph 
pe, one directly down 
wo points to the left- 
nt sheet of acetate ap- 
| a straight line is ruled 
iis transparency so that 
red center. 
nsparency overlay the 
ind lower points. 
hotograph, oriented so 
both the center point 
. marked on the trans- 
id. photograph. 
point, the points cor- 
f the Jeft-hand photo- 
the previous center as 
marked on the trans- 
rlies the corresponding 
ruled line still passes 
jonding to the photo 
The distance from the 
marked on the trans- 
either the two points 
s marked for the lower 
(519) 
  
  
  
Left hand photo À 
  
Fig. 3. 
EXPLANATION OF FIGURE 3. 
The figure represents the plan view of the left-hand photograph of the stereo pair, 
showing the construction lines necessary for obtaining the corrected horizontal distance 
between u and |, as described in Section IIIB and D. 
The following are definitions and explanations of the various lines and points: 
u the photo position of the upper point of the dip slope or bedding trace. 
| the photo position of the lower point of the dip slope or bedding trace. 
ul is in the direction of dip under the stereoscope. 
u, the corrected horizontal position of u, related to the datum plane passing 
through 1. 
c, the photo center of the left-hand photograph. 
1, the intersection of a strike line projected through, and a dip line projected 
through cl. The intersection is at the same elevation as I. 
u, the intersection of a strike line projected through u,, and a dip line projected 
through c, |. This intersection is at the same elevation as I. 
u, u total net radial displacement of u in relation to |. 
u,u, net displacement in direction of dip of u in relation to |. 
cjl, and u, are construction lines drawn geometrically at right angles to the strike.