Outline for Preliminary Report on Mineral Claims 97 



strata are vertical the true thickness is shown and strike and 

 outcrop become coincident. 



Fig. 9. Width of an outcrop affected by angle of dip (after Geikie). 



Fig. 10. Width of outcrop affected by lorm of ground. The beds 1, 2, and 

 3 are of equal thickness but their outcrops vary in width, owing to 

 the topography. Bed 1, appearing on flat land, yields a broad outcrop 

 (after Geikie). 



VIII. COAL BEDS 



1. Take numerous dip and strike readings at different points 

 on the outcrop or at the mine faces. 



2. Measure the width of the vein at different outcrops and in 

 all mines and prospects located on the claim. Notice par- 

 ticularly pinching, swelling and parting of the vein, if such 

 conditions prevail also the character of the vein throughout 

 the coal field as a whole, and its relation to other veins. 



3. Describe the physical properties of the coal, giving color, 

 luster, cleavage, hardness of weathered and unweathered 

 samples, and size of lumps on air slacking. 



4. Give thickness of shale or "bone" partings, if any. Give the 

 kind of rock composing the hanging and foot walls. 



5. Collect samples for analyses, following method outlined by the 

 United States Geological Survey. 



The following rules in sampling coal mines have been 

 adopted by the United States Geological Survey : 



