The Grit. 223 
cess, though they adjusted themselves to such a degree that the 
pressure did not crush them. 
That there has been an actual turning is shown by the 
sericite flakes which surround the grains. The orientation of 
the sericite, so noticeable a feature of the schists, is wholly de¬ 
stroyed and broken up in the immediate neighborhood of the 
grains. The flakes orient themselves with the outline of the 
grain however irregular that may be. They follow each irreg¬ 
ularity, wherever a projection occurs on the grain the flakes are 
much more crowded and confused on one side of the projection 
than the other, the side toward which movement was taking 
place, the flakes of sericite have not only concentric arrange¬ 
ment but also a spiral arrangement, the whorls gradually con 
tracting as the grain is approached. The sericite flaxes have 
an arrangement, not unlike that of chips in a swiftly moving 
eddy, they are oriented but gradually grow together and form 
more and more contracted circles as the garnet grain is ap¬ 
proached. The grains themselves are broken across, one frag¬ 
ment being crowded over the other or turned more than the 
other so as to be in more perfect orientation than the other. 
In such cases fracture arises from the inability of the grain as 
a whole to accommodate itself to the turning movement, the 
fragment breaks and one portion is thereby more easily permitted 
to get into alignment with the crushing force. The explana¬ 
tion of this phenomenon seems to be closely connected with the 
particular type of cleavage here developed. In all these schists 
the cleavage is Sorby’s second type “slip-strain” cleavage, or 
the “ Ausweichungs Clivage ” of Heim. Gliding planes are fre¬ 
quently developed, they are rendered easy of motion by the abun¬ 
dant development of sericite flakes, along these planes therefore 
easy motion takes place. Between the planes of movement 
occur the garnet grains, the upper plane moves in one direction 
the under plane in the opposite, the result of these opposite 
movements upon any body between them is to roll it around in 
the direction toward which the plane moves, the top is pushed 
in one direction the bottom in the other a slow revolution takes 
place if the grains were of such shape as to admit this, motion 
taking place until the larger diameter of the included fragment 
