ON AN EXPERIMENTAL INVESTIGATION INTO THE FLOW OF MARBLE. 
.305 
solution and redeposition of the minerals which make up the rock. The percolating 
waters, it is held, tend to dissolve material at those points where the pressure is 
greatest, and to redeposit it where the pressure is wholly or partially relieved ; the 
movements thus being accompanied by a more or less complete recrystallisation of the 
whole rock. Moisture would thus be a necessary factor in all rock folding or 
contortion, and recrystallisation the essential feature of the phenomenon. The 
deformation of a body of dry rock would be impossible. The opinion that water is a 
very important, if not an absolutely essential, factor in the folding of rocks was held 
by MacCulloch, De la Beche, and a number of the earlier geologists; who based 
their opinions on the fact that rocks are often much softer while they still contain 
their quarry water than after they are thoroughly dry, a fact which has been 
emphasised by tests of the relative strength of wet and dry rocks recently carried out 
at the arsenal at Watertown, Mass. # It is a matter of great difficulty, and, in fact, 
in most cases it is quite impossible to decide with certainty upon the relative merits 
of these conflicting views from a study of the deformed rocks themselves. Had this 
been possible, the controversy would long since have been brought to a close. Heim, 
however, in his great work on the ‘ Mechanism of Mountain Making,’f published 
some twenty years since, refers to the very valuable results which might he looked for 
in elucidation of these questions from carefully conducted experiments upon the 
deformation of rocks under conditions as nearly as possible approximating those which 
* obtain in the deeper parts of our earth’s crust. He expresses grave doubts, however, 
as to the possibility of reproducing the conditions in question, j 
From the time of Sir James Hall§ experimental investigations have been under¬ 
taken at intervals, aiming more particularly at the reproduction of the forms exhibited 
by folded strata. Those by Daubree,|| Beyer, If Cadell,* * * § ** * * §§# Favre,! t Obermeyer,JJ 
Forcheimer,§§ and Bailey Willis[| j| may be especially mentioned. In these experi- 
* ‘Report of the Tests of Metals and other Materials for Industrial Purposes made at Watertown 
Arsenal, Mass., during 1894,’ Washington, Government Printing Office, 1895. Also subsequent Report of 
same series for 1895. 
f ‘ Untersuchungen fiber den Mechanismus der Gebirgsbildung,’ vol. 2, pp. 4, 84. 
| “ Zum Mechanismus der Gebirgsbildungen,” ‘ Zeit. d. dcutsch. Geol. Gesell.,’ 1880. See also Baltzer, 
‘ Der Glarniseh,’ p. 52. 
§ “ On the Vertical Position and Convolutions of Certain Strata,” ‘ Trans. Roy. Soc. Edin.,’ vol. 7, 
1815. 
|| ‘Etudes Synth etiques de Geologie Experimentale,’ Paris, 1879. 
II ‘Ursachen der Deformationen und der Gebirgsbildung,’ Leipzig, 1892. 
** “Experimental Researches in Mountain Building,” ‘ Trans. Roy. Soc. Edin.,’ vol. 35, 1888. 
ft “The Formation of Mountains,” ‘Nature,’ December 5, 1878. 
\\ “ Versuche fiber das Ausfluss plastischen Thones,” ‘ Sitz. der Wiener Akad. Math.-Natur. Class,’ 58, 
1868. 
.. * 
§§ “ Uber Sanddruck und Bewegungs-Erscheinungen im Inneren trockenen Sandes,” ‘ Inaugural 
Dissertation der Eberhard-Carls-Universitat in Tfibingen.’ Aachen, 1883. 
(Ill ‘Thirteenth Annual Report U.S. Geological Survey.’ 
