SOME EXPERIMENTS IN FOLDING 



R. T. CHAMBERLIN and F. P. SHEPARD 



University of Chicago 



In 1812 Sir James Hall, using some pieces of cloth and a door 

 "which happened to be off its hinges" and a few stones to act as 

 weights, reproduced the contortions of the strata shown by the 

 Berwickshire coast. This suggestion was revolutionary, for folding 

 of strata had not previously been recognized/ Since that beginning, 

 experimentation in folding has been carried on by many different 

 investigators, among whom may be mentioned Favre, Daubree, 

 Pfaff, Forscheimer, Schardt, Reade, Cadell, Willis, Avebury, 

 Paulcke, Konigsberger, and Mead. No attempt will be made here 

 to discuss in detail the results of these researches. 



For many of the present experiments the pressure apparatus 

 utilized was the crushing box previously used for experiments in 

 faulting which have already been described.^ Pressure can be 

 applied simultaneously from both ends, if desired. As one side of 

 the box can be removed at will, the progress of the folding can be 

 observed and photographed at any stage of the deformative pro- 

 cess. A comparison of the progressive changes and characteristics 

 of the folds during the different stages of compression constituted 

 an important part of the investigation. In most of the tests sand 

 was placed both above and below the layers to be folded. This 

 gave an adaptive support below, and effected a well-distributed 

 weighting above. Heavy blocks of stone were placed upon the sand 

 to afford sufficient overburden. 



After testing various materials, mixtures of paraffin and vaseline 

 were found to yield the most satisfactory results, and were employed 

 in different proportions, depending upon the degree of competency 

 desired. Pure parafi&n was found to be too brittle for pronounced 



'J. S. Flett, "Pres. Address, Sec. C," Repl. British Assoc. Adv. Sci., 1921, p. 73. 

 ' R. T. Chamberlin and W. Z. Miller, "Low Angle Faulting," Jour, of GeoL, Vol. 

 XXVI (1918), p. II. 



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