THE ROCKS OF PLYMOUTH. _ 243 
The granite immediately adjacent to the junction at Lee Moor 
is in part very compact and highly crystalline, of moderate grain, 
and. suggests consolidation under great pressure, with tolerable 
rapidity, from a magma in which the elementary constituents were 
well blended. At other points felspar and mica are the only 
prominent features of the junction granite; and again some of 
the contact rocks are almost wholly composed of a felted mass of 
small brilliant prisms of schorl, with here and there a partially- 
kaolinized erystal of felspar. If this rock was originally a slate, 
it has undergone the most marked change of any with which we 
have to deal in this connection. One Lee Moor contact granite is 
fine-grained, compact, largely quartzose, with schorl and a little 
mica. The distance between this and schorl-rock proper would 
be very small. 
An example of granite next mica-schist at Shaugh is very 
coarse-textured, chiefly composed of felspar in large crystals, with 
the mica and quartz finely segregated in nests between. Ivybridge 
supplies a distinct red contact granite, next slate converted into 
micaceous-schist. At Brazen Tor there is a fine-grained granite 
next the junction with amphibolite, but the granite of the tor 
itself is very coarse and porphyritic. The development of horn- 
blende in the igneous rocks of this locality and elsewhere by the 
action of the granite has been already considered. 
The changes produced in the surrounding rocks by the granite 
are indeed very interesting. The alteration in the adjacent belt 
of slates, as a rule, proceeds so systematically that it would be 
quite possible with a little trouble to locate, within a very few 
yards, the position of a stray specimen from any given area. 
There are, however, differences in the changes in different localities, 
apparently due to two causes—first, the original character of the 
rock altered ; secondly, the relation borne to it by the granite in 
bulk and position. 
Now the great change produced in the slates along the southern 
border of our granitic region is their conversion into spotted slates 
or schists by the development of nodules or crystals, more or less 
imperfect, of andalusite, or its variety chiastolite. The words in 
which the late Mr. Clifton Ward describes the altered slates of 
Skiddaw apply very closely to those of South Devon. He says: 
‘On approaching the altered area the slate first becomes faintly 
