BARKER : LAKE DISTRICT IGNEOUS ROCKS. 
493 
The foregoing include all the more important igneous rocks of 
the district. Since one object of these brief notes is to assist in the 
identification of Lake District boulders in other areas, it is desirable 
to point out which of the rocks have sufficiently distinctive characters 
to be recognised with tolerable certainty. The following include the 
most important for this purpose : the porphyritic hypersthene-basalts 
(Eycott type), the amygdaloidal andesites, volcanic breccias with 
pink rhyolite-fragments, garnetiferous breccias and tuffs, the banded 
tuffs and the hornstones, some rhyolites and especially the nodular 
rhyolites, the Threlkeld microgranite, the Armboth type of grano- 
phyre, the olivine-diorite (Little Knott type), the three difl:erent kinds 
of granite, and the different varieties of the Carrock Fell gabbro. 
The quartz-gabbro, it may be mentioned, is often indistinguishable 
from the coarse type of the Whin Sill in Teesdale, and it is possible 
that some records of " Whin Sill " boulders require reconsideration. 
Some of the metamorphosed rocks bordering the granitic intrusions 
are at least as distinctive as many of the igneous rocks themselves. 
The chiastolite-slate of Sinen Gill and the more highly metamorphosed 
rocks, with andalusite, cordierite, &c., in Grainsgill and the Caldew 
Valley should be noticed ; and again the metamorphosed basaltic 
lavas near the Eskdale granite. The metamorphosed volcanic rocks 
are even more characteristic near the Shap granite, the basalts on 
the north side becoming black splintery rocks with hornblende, 
pyrites, and other new-formed minerals, and the andesites on the 
west being converted into dark glossy rocks rich in minute flakes of 
biotite. 
