Vol. 58. ] CRYSTALLINE LIMESTONES OF CEYLON. 411 
(possessing the usual characters) is separated from the limestone by 
a zone of hard, compact, greenish-grey rock, 1 to 13 inches wide, 
which borders it like a shell. This greenish zone (specific gravity 
= 3:12, 3°25) is composed almost entirely of compact granular 
diopside, with some green spinel in parts, and peripherally a 
little interstitial calcite. Where the calcite 1s more abundant, 
the diopside and spinel are idiomorphic. After running for some 
yards as such, the band is continued as a series of lenticles, 
the structure of which is identical with that of the band. The 
band of acid granulite is thus, as it were, interrupted by trans- 
verse dykes of limestone. A specimen of acid granulite from the 
interior of one of the lenticles contained augen-orthoclase, measuring 
as much as 23x13 millimetres. A thin slice showed a fine- 
grained granular mosaic of orthoclase-microperthite, traversed by 
strings of individuals of elongated quartz, and containing irregular 
porphyritic individuals of microperthite which appear strained and 
perhaps fractured. The band and lenticles can be traced for quite 
15 yards, appearing again beside the road, north of the exposure 
in the shallow quarry. 
It is exceedingly interesting to compare these broken sills of 
granulite in limestone with the broken dykes of nepheline-syenite 
in the limestone of Alno (described by Prof. A. G. Hogbom),' the 
peculiar characters of which seem to correspond closely with those 
of the cases just: described. 
Before leaving this part of the subject, it may be useful to point 
out that the various bands of granulite met with in the limestones 
occur always as sills, and never as transverse dykes. 
If we suppose the granulite to be intrusive in the limestone, we 
must regard this parallelism as the result of injection accompanied 
by lateral pressure. 
TV. InrereRowrus oF Catcire AND DoLoMITE. 
These are very characteristic of the crystalline limestones, 
especially in the Kandy and Matale districts, though rather unusual 
in the neighbourhood of Hakgala. Such intergrowths produce 
characteristic appearances on weathered surtaces. 
Parallel intergrowths (fig. 5, p. 412).—It is very usual for 
the white carbonate-crystals composing the limestone to show a 
curious banding, well brought out on weathered surfaces. In such 
cases, there is a scries of narrow parallel bands running across the 
crystal, diagonal to the cleavage, and alternately standing out and 
depressed. In the coarsest variety found, there were 15 upstanding 
bands to the half-centimetre. There are all transitions from this type 
to bandings of microscopic dimensions. Thin sections show that 
this appearance is caused by a parallel intergrowth of calcite and 
dolomite, in alternating planes parallel to the basal plane ¢(001). 
* Geol. Foren. Stockholm Férhandl. vol. xvii (1895) pp. 100, 214. 
