8i2 rRINCIPLES OF STRATIGRAPHY 



is the component of the sHp parallel with the strike, and the dip- 

 slip (hade slip) the component parallel with the dip. Thus (in 

 Fig. I93h) a & is the net slip, a c the strike-slip and /) c the dip- 

 slip. 



The shift is the relative displacement of the rock masses outside 

 of the zone of displacement, and is used when there are many minor 

 slips making up the shear zone or when the strata in the neighbor- 

 hood of the fault are bent. It is the relative displacement which 

 would exist had there been only one slip of the same magnitude as 

 the combined minor slips. 



Features shozvn in section of faults. 



Throzv is the vertical displacement of the strata, as seen in sec- 

 tions, even if the slip is inclined, d e in the figures (No. 194, A B). 



A . B ■ 



Fig. 194. Sections of faults: A, with dip of fault plane across strata; B, 

 with dip of fault plane in same direction as dip of strata. 



Heave or horizontal throw is the horizontal displacement of 

 strata seen in section, as e g in the figures (No. 194, A B). 



Stratigraphic throw. This is the distance between the two parts 

 of a disrupted stratum measured at right angles to the plane of the 

 stratum, (a b, Fig. 194, A B.) 



The stratigraphic heave, or dip throw, is the displacement of 

 the strata in section in the direction parallel to the strata, as c b in 

 Fig. 194, A B. In Fig. A it signifies shortening and overlapping of 

 the strata, in Fig. B, lengthening by separation of the strata. 



