476 Adams <& Coker — Investigation into the Flow of Rooks. 



A faint but distinct cataclastic structure is, however, found 

 in some Cases even when the support offered to the marble by 

 its steel tube is perfect, and along planes of greatest move- 

 ment the calcite individuals can in some cases be seen to have 

 been apparently slightly torn. 



(b) Deformation at very high pressures — Structure of the 

 deformed marble. 



In order to ascertain whether under a greater load the cata- 

 elastic structure would entirely disappear, another series of 

 experiments were carried out employing much higher pressures 

 and at the same time carrying the deformation as far as pos- 

 sible. This was secured by increasing the thickness of the 

 wall of the tube which enclosed the marble. A tube of 

 wrought iron built up in the same manner as a gun barrel and 

 having a wall thickness of *5 inch (12*7 mi11 ) for a length of "625 

 of an inch (15*875 mm ) along the central portion of the tube 

 about the enclosed marble column was employed. Steel pis- 

 tons were then inserted and the pressure applied in the usual 

 way. The tube commenced to bulge when the pressure 

 reached 35,000 lbs. (15,870 kilos.), and the maximum load 

 applied to the marble was 154,000 lbs. (169,750 kilos.), that is 

 to say, a pressure of 296,725 lbs. per square inch (20,875 kilos, 

 per square cent.), the deformation being carried on slowly and 

 occupying forty-one hours. This is equivalent to a depth of 

 46 miles below the surface of the earth. A photograph 

 of the tube upon the completion of the experiment is shown 

 in Plate II (a). Under this tremendous pressure the upper 

 steel piston failed, four radial cracks developing on its face in 

 contact with the marble, thus dividing the piston face into 

 four nearly equal quadrants. These cracks extended up into 

 the piston for approximately half an inch (12*7 mm ), the largest 

 of them being one one-hundredth of an inch ( , 254 mra ) in width 

 at its widest part, and the marble was forced up into these 

 very narrow cracks. Notwithstanding the great thickness of 

 the ends of the tube, moreover, a small amount of the marble 

 under this enormous pressure passed up between the piston 

 and the inner surface of the tube, in a form which while cohe- 

 rent was sufficiently soft to yield to the finger nail with ease. 

 The marble was removed from the bulged tube by turning off 

 the latter in a lathe. That portion of the rock which had not 

 been forced up around the pistons, constituting of course 

 almost the entire mass, was obtained in the form of a slaty 

 •cake -682 inch (17-3 mra ) in height and 1-135 inch ' (28'81 mm ) 

 wide at its widest part, and in form somewhat barrel-shaped. 

 This is shown in Plate II b with a column of its original dimen- 

 sions placed beside it for purposes of comparison. On the 



