Dr. C. Ricketits—Changes in the Earth's Crust. 116 
tains large eyes of that rock. It can be studied to much advantage — 
towards the east end of the Cove, where the huge eyes of the horn- 
blende-schist are distinctly seen gradually to pass into the felsitic 
rock, which in turn passes into the hornblende-schist at either 
extremity of the Cove, thus precluding the idea of the former rock 
being intrusive in the latter. 
In my short communication! to the Macazine for December last, 
I referred to the various rocks and minerals formed out of a magma 
cooling under different conditions, or by its mineral constituents 
separating during the cooling process. In the present instance we 
note what seems equally referable to subsequent mechanical and 
chemical change after the rock had passed into a consolidated state, 
as attested by the breccia and the highly altered condition of the 
hornblende-schist. This is but one among the many examples of 
these Lizard schists passing into each other. Such a passage may 
also be noted between the hornblende, the mica-diorite, the mica- 
schist, and other varieties. In the field we catch them, as it were, 
in the very act of alteration into each other, at least we can observe 
them in all their transition stages, and these from their decidedly 
squashed appearance, their frequent lenticular, irregular, and other 
inconstant characters, betray their dynamic and secondary origin. 
Still it must, I think, be conceded that however much dynamic 
metamorphism may have altered these Lizard rocks from their 
original mineral aspects, every such change in the main has been 
predetermined by some difference in there primary composition. 
VII.—On some Puysican Cuancus In THE Hartu’s Crust. 
(Part II.) 
By CHaR es Ricxerts, M.D., F.G.S. 
(Continued from p. 53.) 
UBTERRANEAN landslips differ from landslips occurring in 
cliffs along the coast, and in escarpments elsewhere, in that, a 
fissure having been formed and its sides become separated (Figs. 2 
and 38 a), so that they are without support along the line of division, 
it may happen that by the giving way of some soft or unconsolidated 
stratum (b), at any depth, from a few feet only, down to the molten 
nucleus, wedge-shaped masses (c) extending parallel to the fissure 
1 On a Remarkable Dyke in the Serpentine of the Lizard. 
