40 



GEOLOGY 



Fig. 17. Closed anticlinal fold, near Levis Station, Quebec. (U. S. Geol. 



Surv.) 



so that beds which were once horizontal now dip; that is, they 



depart from horizontality. The beds 

 of sedimentary rock may even be 

 on edge (Fig. 18), having a dip of 

 90. The beds of a given region 

 may all dip in one direction, or the 

 dip may change from point to point. 

 They may be folded, and the folds 

 may be open (Fig. 16) or closed (Fig. 

 1 7) . These diverse positions in which 

 strata are found are the result of 

 disturbance subsequent to their deposition. 



Besides being folded, the beds of sedimentary rock are often 

 jointed (Fig. 2) the same as igneous rocks. Slipping may lake 

 place along the joint planes, producing faults (Fig. 19). The joints 

 of sedimentary rock may be filled by the deposition of mineral 

 matter from solution, making veins (Fig. 20). Other secondary 



Fig. 18. Isocline. (Van Hise, 

 U. S. Geol. Surv.) 



