448 METHOD OF MEASURING INCLINED STRATA. 



In the sketch the dip of the strata is 54° to 65°, and the inclination 

 of the iod from the vertical the same, from the horizontal it is3G°to25°. 



The total thickness of the strata between the points a and b is equal 

 to the sum of the nine measurements. If, as is the case with myself, 

 the compass sight be o feet 8 inches from the base of the rod, it is 

 9 times 5 feet 8 inches, or 51 feet for the entire thickness, or 39 feet 8 

 inches for the limestone and 11 feet 4 inches for the shale from c to b. 



The method of measurement is simple, and always available when a 

 suitable stick cf sufficient length can be obtained for holding the com- 

 pass. It saves time and is sufficiently accurate for most field-work. If 

 a Locke level is also carried by the geologist, to be used in measure- 

 ments of horizontal strata, he can measure strata of any degree of dip, 

 and know, after once passing over the section, very nearly the exact 

 thickness, on the spot, without an elaborate series of measurements and 

 calculations, as he has only to multiply the number of measurements 

 made by the distance between the base of the rod and the sights of the 

 compass, or, if measuring horizontal strata, the sight of the Locke 

 level. I have used this method during two field seasons and find it the 

 most satisfactory of any known to me. 



