200 



THE POPULAR SCIENCE MONTHLY. 



STUDIES IN EXPERIMENTAL GEOLOGY. 



Br STANISLAS MEUNIEK. 



MA. DAUBREE, in his recently published " Etudes Synthetiques 

 de Geologie Experimentale " (Synthetic Studies in Experimen- 

 tal Geology), besides giving the results of studies on the formation of 

 meteorites and on the production of the chemical and physical phe- 

 nomena of geology, describes a series of interesting and instructive 

 experiments upon the manner in which the mechanical operations of 

 which the earth's strata bear witness were brought about. 



M. Daubree began this series of experiments with an investigation 

 of the processes by which the convolutions of the stratified beds were 

 produced. With a very simple apparatus, a frame of iron strengthened 

 by long screws crossing two of its contiguous sides, he subjected flex- 

 ible lamina?, as representing in miniature the strata of the globe, to 

 pressures of varying energy and direction. Under these constantly 



measured efforts he saw reproduced 

 all the characteristic traits of the 

 geology of regions whose strata 

 are warped, synclinal valleys, anti- 

 clinal crests, slopes, and reversals 

 of strata, strata in the form of C, 

 strata in the form of S, etc. 



Prosecuting his experiments be- 

 yond the limits of the elasticity of 

 bent laminae, M. Daubree went into 

 the investigation of the origin and 

 mode of formation of terrestrial 

 fractures. He was able by means 

 of his new processes to produce 

 imitations of joints and faults in all 

 their details. An unforeseen result 

 of his experiments was, that they 

 disclosed evidences of mutual co- 

 ordination between natural frac- 

 tures which observation alone had 

 failed to notice. This point de- 

 Fig. l Double system of conjugate fractures serves a careful examination. A 



rectangular plate of glass, G G (Fig. 

 1), was clamped between two jaws 

 of wood tightly bound by screws 

 so as to form a kind of vice, E E. The other end of the plate was 

 fitted to a wrench, T T. By turning the wrench around horizontally, 

 M. Daubree twisted the plate of glass so that it speedily broke into 

 a thousand pieces. Having previously taken care to paste a sheet of 



developed in a plate of glass, G G, by the effect 

 of the torsion produced by the turning-handle, 

 T T. E E, block of wood in which the other 



end of the glass plate is fastened, 

 the natural size.) 



(One sixth 



