Vol. 58.] THE WOLLASTONITE-SCAPOLITE GNEISSES OF CEYLON. 687 
found, and have been briefly described by me in a former paper.’ 
A quartz-calcite-micropegmatite occurred in one variety. No 
information concerning the field-relations of these rocks is available. 
Rocks evidently similar to the Galle type occurred in a small 
exposure on the shore at Pittiwela, a few miles north of Galle. 
Specimens from this locality consisted of augite, scapolite, and 
sphene. The small exposure seemed to be quite isolated on the 
sandy shore. 
Some charnockite-limestone contact-rocks in Ceylon resemble rock- 
types occurring at Galle, as, for example, the scapolite-augite rock 
with sphene, which occurs associated with crystalline limestone at 
Herimitigala*; but the contact-rocks, on the whole, are of a rather 
different type, the absence of wollastonite being especially noticeable, 
Prof. Lacroix’s specimens indicate the existence of wollastonite- 
and scapolite-gneisses in some other parts of Ceylon. 
VY. ConcLusions. 
The Galle Group includes a series of rocks allied to, and part of, 
the Charnockite Series in Ceylon. Like those of that series, it is 
clear that the Galle rocks must be classed as orthogneisses, for they 
have evidently consolidated from a magmatic condition. The 
wollastonite and scapolite are original minerals, and certainly not 
decomposition-products from felspars or other minerals. They are 
often associated with felspars which are in a perfectly fresh condition. 
This original character of wollastonite and scapolite in some gneisses 
rich in lime is well recognized. Wollastonite has even been found 
as an original mineral in eruptive rocks. 
Possibly the richness in lime of some of the Galle rocks is due to 
the total absorption of a large mass of limestone (whether originally 
of sedimentary origin or otherwise) by a portion of the Charnockite 
Series. It may, however, have been an original character of the 
magma. Scapolite-pyroxene rocks are sometimes found at the 
junction of limestone and charnockite in Ceylon.* Wollastonite 
has not, however, been found in such situations. If the 
absorption-theory be accepted, the lime-silicate minerals must 
be regarded as endomorphic contact-minerals. In any case, the 
Galle rocks seem to show clear indications of progressive 
differentiation from basic to acid types; the coarse segregation- 
veins seem to be the last product of such a process. There is no 
reason to regard the graphite-flakes as other than original and 
crystallized from the magma. 
That the Galle rocks have not suffered from deforming earth- 
movements since their complete consolidation is evidenced by their 
microscopic characters, and by the segregation- veins and dykes which 
+ ‘Ceylon Rocks & Graphite’ Quart. Journ. Geol. Soc. vol. lvi (1900) p. 602, 
2 * Crystalline Limestones of Ceylon’ ibid. vol. lviii (1902) p. 407. 
2 Ibid. pp. 405 et seqq. 
