456 PROCEEDINGS OF THE ALBANY MEETING 



fact which was recognized by the earliest geologists, and it needs but a glance at 

 an}^ of the accurate sections of contorted regions of the earth's crust which have 

 been prepared in more recent years to show that there is often a transfer or " flow " 

 of material from one place to another in the folds. The manner in which this con- 

 tortion, witli its concomitant " flowing," has taken place is, however, a matter 

 concerning which there has been much discussion, and a wide divergence of 

 opinion. Some authorities have considered it to be a purely mechanical process, 

 while others have looked upon solution and redeposition as playing a necessary 

 role in all such movements. The problem is one on which it would appear that 

 much light might be thrown by experimental investigation. If movements can 

 be induced in rocks under known conditions, with the reproduction of the struct- 

 ures found in deformed rocks in nature, much might be learned concerning not 

 only the character of the movements, but also concerning the conditions which 

 are necessary in order that the movements in question may take place. 



It is generally agreed that three chief factors contribute to bringing about the 

 conditions to which rocks are subjected in the deeper parts of the earth's crust, 

 where folding with concomitant flowing is most marked. These are: 



1. Great pressure. 



2. High temperature. 



3. Percolating waters. 



With regard to the first factor, it must be noted that mere cubic compression 

 does not produce movements of the nature of flowing, although it may produce 

 molecular rearrangement in the rock. A difierential pressure is necessary to give 

 movement to the mass. As Heim has pointed out, there is reason to believe that 

 " Umformung ohne Bruch " takes place when a rock is subjected to a pressure 

 which, while greater in some directions than in others, in every direction exceeds 

 the elastic limit of the rock in question. Whether all these factors, or only cer- 

 tain of them, are actually necessary for the production of roctk deformation is a 

 question which also requires to be determined by experiment, for by experiment 

 the action of each can be studied separately, as well as in combination with the 

 others. 



In the present paper a first contribution to sucii a study is presented, pure 

 Carrara marble being the rock selected for study. The investigation is now being 

 extended to dolomites, granites, and other rocks. 



In order to submit the marble to a differential pressure, under the conditions 

 above outlined, it was sought to inclose the rock in some metal having a higher 

 elastic limit than marble and at the same time possessing considerable ductility. 

 After a long series of experiments heavy wrought-iron tubes of special construction 

 were adopted. These were made, followiug the plan adopted in the construction 

 of ordnance, by rolling thin strips of Low Moor iron around a bur of soft iron and 

 welding the strips successively to the bar as they were rolled around it. The core 

 of soft iron composing the bar was then bored out, leaving a tube of Low Moor 

 iron, the sides being about one-fourth of an inch in thickness, and so constructed 

 that the fibers of the iron ran around the tube instead of being i)arallel to its 

 length. These were found to answer the requirements admirably. 



The following procedure was then adopted : Columns of the marble, an inch or 

 in some cases 08 inch in diameter and about 1"5 inch in length, were accurately 

 turned and polished. The tube was then very accurately fitted around the marble. 

 This was accomplished by giving a very slight taper to bqlh the column and the 



