ON AN EXPERIMENTAL INVESTIGATION INTO THE FLOW OF MARBLE. 395 
The structure of this rock is due in part to cataclastic action, but chiefly to the 
deformation of the calcite grains by motion on their gliding planes. Evidently the 
original blue limestone was recrystallised throughout the greater part of its mass, 
with the development of numerous secondary minerals, and the whole was then 
subjected to dynamic action, which resulted in the movements described, which, 
while affecting both rocks, are most noticeable in the coarser-grained marble. 
14. Limestone. Ijot 27, Range XIV., Township of Monmouth, Ontario. —Identical 
in character with No. 13. 
15. Marble. Lacliute, Province of Quebec. —This rock has a very distinct foliated 
structure, the plane of foliation being emphasised by the presence of little graphite 
flakes, which have the appearance of being smeared along it. The rock has a marked 
cataclastic structure, and has clearly been derived from the squeezing of a coarse¬ 
grained marble. The deformation of the calcite grains, accompanied by strain 
shadows, is very marked in all but the smallest grains, which would probably show 
the phenomenon also if then* surfaces were sufficiently large to render the shadows 
visible. Twinning is also common, although many grains which show a marked 
deformation are free from all traces of it. While, therefore, the structure is 
cataclastic, it is combined with a most marked development of deformation of the 
calcite grains by movement along their gliding planes. 
Mesozoic Limestones from the Alps whose Structure is of Doubtful Origin. 
The Jurassic limestones which have been caugbt up in the mighty foldings of the 
Alps, and which are found not only in the flanks of the mountain system but along 
certain lines in the deep synclinals of the chain, although extremely compressed and 
contorted, in many cases show but little signs of alteration, while elsewhere they 
have become converted into coarsely crystalline marbles. The marbles of Andermatt 
(No. 3) and of Schaftelen (No. 4) are believed to be of Mesozoic age, and to represent 
these limestones in their highly altered condition ; while the limestones of Biitzistockli 
(No. 5) and Minis (No. 6) represent the rocks in a comparatively unaltered state. The 
former, as has been shown, present certain structures which are clearly attributable to 
deformation under pressure, but in some of the mesozoic limestones which have un¬ 
doubtedly been extremely plicated and subjected to enormous internal movements, the 
evidence of these movements in the minute structure of the rock is by no means striking. 
To the latter class belongs the rocks of this division, Nos. 16 to 21. Their structure 
is in all cases essentially the same, and they are closely related to Nos. 5 and 6 
described above. This structure is that which is the most important element in Heim’s 
“ Umformung ohne Bruch.” The individual grains of calcite are flattened at right 
angles to the pressure, and in the direction of the movement of the rock. Whether, 
however, this flattening, inducing what Heim terms “ microclivage,” has been brought 
about by pressure, the flattened grains flowing on their gliding planes and moving over 
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