G. F. Becker — Impact Friction and Faulting. 209 



fact affords a distinction which may in some cases serve to de- 

 cide the character of a particular fault. 



Since different lines of research lead to the principle of the 

 logarithmic distribution of energy in systems of sheets connect- 

 ed by friction, and since this result is confirmed by experiments 

 and observation it appears to me that it may fairly be claimed 

 as established and as affording a valid explanation of the 

 structural problems presented by step-faults, parallel systems 

 of veins, and of some monoclinal faults and landslides.* 



I shall take advantage of the first space which may be allowed 

 me in this Journal, to show that the same principles apply to 

 another and very different problem in structural geology, and 

 to present an entirely fresh proof of the fundamental equation. 



Office of the U. S. Geological Survey, ) 

 San Francisco, February, 1885. ) 



* Mr. Ross E. Browne, of the University of California, has published an attack 

 upon the theory of step-faults given in my report upon the Corastock Lode (this 

 Journal, vol. xxviii, p. 348). I feel great diffidence in opposing my opinions on 

 this subject to those of an author who writes in so authoritative a tone, for my 

 own knowledge of the science of mechanics is rudimentary. I am nevertheless 

 forced to the conclusion that Mr. Browne has failed to perceive the full significance 

 of Morin's laws. To grant that friction is independent of velocity and yet to 

 deny that there will be motion on each contact of a system of sheets, such as that 

 discussed above is simply to deny the presence of a stress, for this independence 

 implies movement (a strain) however slight the stress. But to deny a stress under 

 such conditions would be to deny the principle of the equivalence of action and 

 reaction. So. too, Mr. Browne disputes the applicability of my experiment on 

 sheets of paper as a test of the theory proposed, because the pressure of a blunt 

 edge will not be confined strictly to the same area at each contact. Yet this can 

 make no difference under Morin's laws, since under them the frictional resistance 

 at any contact depends upon the total pressure exerted upon the entire area of 

 the frictional surface and not in the least upon its distribution. Morin's laws 

 formed the basis of my analysis as was stated over and over again in my former 

 paper, though I endeavored to experiment in such a way as to be as little de- 

 pendent upon them as possible. 



Rejecting my explanation of the curve obtained in the experiment Mr. Browne 

 offers as an improvement one founded on what appears to me a strange physical 

 hypothesis and which leads him to the hyperbola y=c/x. In my report, p. 167. I 

 compared the experimental curve with this locus, and showed that the position 

 of the asymptote is fatal to the supposition. If this is not regarded as a sufficient 

 objection the incorrectness of the solution will be evident when it is considered 



that even if the equation is given the form y=c(\ +x)~ , 2(1 +x) =oo ; so that 



o 

 the hyperbolic curve could only result from the application of an infinite amount 

 of energy. In short, without going into further detail, I fail to see that Mr. 

 Browne has pointed out any error in my work or that he has thrown any addi- 

 tional light on the subject. 



