50 New York State Museum 



Horizontal strata are the exception rather than the 

 rule and with or without accompanying folding we find 

 inclined strata. The direction in which the beds incline 

 is the direction of dip or maximum angle of slope of the 

 surface ; the direction in which the edges of the beds ex- 

 tend, that is, the intersection of the inclined strata with 

 a horizontal surface, is the strike, and this is at right 

 angles to the dip (figure 6). The direction of dip and 

 strike is obtained with a compass. The angle of dip, the 

 angle of inclination from the horizontal, is measured by 



Figure 7 Diagram illustrating a homemade clinometer with 

 needle attached as pointer 



an instrument known as a clinometer (Greek klino, to 

 incline; metron, measure). The lower edge is held paral- 

 lel to the dip of the strata and the pointer, which swings 

 free, indicates the number of degrees the beds are dip- 

 ping. A simple clinometer may be made at home with a 

 piece of cardboard or wood, a small weight or needle and 

 thread (figure 7). The board or cardboard should have 

 parallel sides. Fasten to it a semicircle of paper or metal 



