56 «=W. Wl. Hutchings—Altered Igneous Rocks, We tntagel. 
also considerably in amount. Leucoxene and epidote remain in 
about the same proportions as in No. 1. 
But it is more the mechanical than the chemical or mineralogical 
change which is very striking in this part of the rock. It has 
become very much foliated, and sections cut across the schistosity 
show in a beautiful manner what a great amount of stress and 
internal movement it has undergone. 'The chlorite is drawn out into 
long, curving parallel bands and streaks, and most of the calcite and 
leucoxene have been squeezed out into long lenticles, tapering off 
into thin tails. Hornblende also is crushed into layers, but in a less 
degree, and much of it is now in the form of detached needles and 
fibres. Epidote has not been drawn out into streaks, but is more 
broken up and separated and more or less arranged in lines; and 
the irregular bits of this mineral lying in among the bands and 
lenticles of the other constituents which have behaved more 
plastically, often serve to more distinctly mark the amount of ‘ flow” 
which has taken place around their angles. It would be difficult, I 
imagine, to find anywhere a more striking example of the great 
alteration which may be effected in rock-structure by pressure and 
shearing-movement than is here given within a space of some thirty 
yards or less. 
Sections of No. 3 show that hornblende has wholly disappeared, 
chlorite taking its place. Calcite is more abundant than in No. 2, 
while epidote is nearly wholly absent. It may be stated that over 
a large number of sections of rocks of this district which I have 
examined, calcite and epidote very generally appear in’ inverse 
proportions. They are, of course, very liable to be originally 
developed in inverse proportions. They both originate from the 
alteration of the same calcareous silicates, and varying conditions 
under which this alteration is carried on may give rise to varying 
amounts of the two minerals in question, even in closely adjoining 
parts of a rock. But it seems not unlikely that epidote may be 
altered into calcite under some circumstances. I have seen no 
mention of this, nor have I detected any epidote actually under- 
going the change to calcite. Nevertheless, the frequent oscillation in 
the relative amounts of the minerals in these rocks has constantly 
suggested such a change, which is likely enough from a chemical 
point of view, as a possible explanation. 
The most striking change in No. 3, as compared with No. 2, is 
that turbid felspar has now almost entirely given way to water- 
clear. Much of it here shows twinning. It is more or less full 
of bits of chlorite, and other mineral enclosures which cannot be 
determined. Onente has undergone a further very decided increase. 
Leucoxene is still abundant, but some patches of it are seen to be 
very much altered to rutile in grains; and small crystals of rutile, 
some as sagenite, are Abnea in some parts of the chlorite. The 
foliation is seen to be more highly developed, the parallelism of the 
bands of chlorite, ete., being greater, and their course less curved 
and wavy, which corresponds with the much greater tendency of 
this part of the rock to split into flattish pieces. 
