Vol. 58. ] CRYSTALLINE LIMES!ONES OF CEYLON, 423 
magma. As to the original nature of the limestones, he could say 
nothing; the interrupted sills and isolated masses of the granulite 
which had been described were very puzzling facts, and he inclined 
to the opinion that the Author’s contention that ‘the two rocks in 
their present condition are essentially contemporaneous’ was the 
hypothesis most nearly in accord with the facts. 
Mr. Hottanp thought that the Author’s ‘self-imposed task of 
attacking the crystalline problems of Ceylon deserved the highest 
commendation of the Society, and the additional facts now published 
formed a great advance on previous work in that area. But he 
considered that the evidence offered was utterly insufficient to 
establish the Author’s contention that the crystalline limestones 
had bebaved as igneous rocks, and formed part of the magma 
which gave rise to the associated Charnockite Series. He (the 
speaker) had described primary and original calcite in a nepheline- 
syenite from Southern India, as Adams had done for Ontario and 
Hogbom for Alné; and though he was convinced that calcite 
might be dissolved without decomposition, and subsequently sepa- 
rated from a nepheline-syenite magma, in which there was no free 
silica and an excess of electropositive alkali, it would be impossible 
for a limestone and charnockite to come into igneous contact with- 
out a chemical reaction which would result in the alteration of 
both rocks. The phenomena described by the Author were precisely 
those which would be expected theoretically from the intrusion of a 
charnockite into a pre-existing limestone. The limestones had been 
as a whole raised to a high temperature, and (as he had previously 
suggested from other evidence) had been brought to a condition 
probably akin to fusion, in which condition there would be a 
sufficient freedom of molecular movement to account for all their 
structural peculiarities—the intergrowths of calcite and dolomite, 
the flow-structures, and the occurrence of large phenocrysts of 
accessory minerals, which did not indicate an igneous condition any 
more than the large chiastolites of chiastolite-slates. The absence 
of cataclastic structures did not indicate freedom from deformation 
after solidification, as Adams and Nicolson had proved that marble, 
under differential pressure and at a temperature no higher than 
400° C., could be made to flow like glacial ice without the pro- 
duction of cataclastic structures. The plasticity of the limestone 
at temperatures well below the fusing-point of any rock was 
sufficient to account for the stream-like disposition of the in- 
clusions, as well as the dislocation of the charnockite-sills without 
internal deformation. In India are seen corresponding contact- 
phenomena where the charnockites invade aluminous rocks (the 
khondalites of Walker) and siliceous rocks (quartzites of various 
kinds), and these, like the limestones, have their nearest chemical 
equivalents among known sediments. In places these paraschists 
and paragneisses predominate over the orthogneisses ; while in the 
south, where denudation has proceeded to greater relative depths, 
they are subordinate in quantity, and in Ceylon the limestones nuw 
exposed are apparently merc inclusions in the Charnockite Series. 
2e2 
