400 
PEOFESSOE F. D. ADAMS AND DB, J. T. NICOLSON 
Fig. 2. The deformed marble of Experiment A freed from the enclosing iron tube, and 
beside it a marble column of the dimensions which it originally possessed. 
14/13 of natural size. 
Fig. 3. Tube containing the deformed marble, milled open, and the marble split in two 
as described. The marble column in this case was reduced to one-half its 
original height in 4 hours. Natural size. 
Fig. 4. Another experiment similar to that shown in fig. 3 ; the deformation, however, 
is less marked. The experiment in this case occupied 17 days. The 
cones were quite distinct in the original. 10/11 of natural size. 
Fig. 5. Column of marble (Experiment K) deformed at 300° C. The experiment 
occupied 124 days. Beside it is a column of the original dimensions. 
Natural size (very nearly). 
Fig. G. In this case the pressure on the marble was continued so long and the 
deformation carried so far that the moving marble within tore the iron 
tube apart, as shown. This tube when opened is shown in fig. 3. 
PLATE 24. 
Fig. 1. Microphotograph of the Carrara marble used in the experiments. The 
rock as found in nature. The individual grains have very nearly the same 
diameter in every direction, although differing somewhat in size among 
themselves. Twinning is seen only in two or three grains, and in these is 
represented by a few broad lamellae. Photographed in ordinary light. 
X 50 diameters. 
Fig. 2. A microphotograph of the Carrara marble after having been slowly deformed 
during 124 days at a temperature of 300° C. The individual grains can be 
seen to be distinctly flattened in a horizontal direction, giving a certain 
foliation to the rock, and to possess the fibrous appearance referred to in the 
text as due to polysynthetic twinning. Photographed between crossed 
Nicols in polarised light. X 50 diameters. 
Fig. 3. Microphotograph of the Carrara marble deformed at 400° C. A uniform 
mosaic of somewhat flattened grains, free from all fracturing or cataclastic 
action. Photographed in ordinary light. X 70 diameters. 
Fig. 4. Microphotograph of a few grains of the calcite on the thinnest edge of a 
section of the deformed marble shown in fig. 2. The polysynthetic twinning 
is well seen. Two sets of twin lamellae cross one another in the large grain, 
curving somewhat, and varying more or less in width from place to place. 
Photographed between crossed Nicols in polarised light. X 150 diameters. 
