422 Geological Society: — 



The crystalline limestones of Ceylon are intimately associated with 

 the banded pyroxene- and acid granulites (Charnockite Series). They 

 form bands with outcrops from a few feet to over a quarter of a mile 

 in width, interbedded with the granulites. The limestones themselves 

 have a banded structure (foliation) parallel to that of the granulites 

 and to the boundaries. This foliation of the limestone depends on 

 variations in structure, amount of accessory minerals, and relative 

 proportion of calcite and dolomite. The grain is coarse, sometimes 

 exceedingly so. Parallel and graphic intergrowths of calcite and 

 dolomite are very characteristic. The most abundant accessory 

 minerals are olivine, phlogopite, pink or violet spinel, diopside, 

 pyrite, and blue apatite ; less common are amphiboles, clinohumite, 

 green spinel, etc. The most characteristic contact-minerals are 

 diopside, amphibole, green spinel, and greenish micas ; and, rather 

 in the granulite than the limestone, scapolite, phlogopite, diopside, 

 spbene. There occur also in the limestones, nodular mineral 

 aggregates composed of characteristic minerals such as diopside, 

 phlogopite, blue apatite, and spinel. 



There are often transitions between the limestones and granulites. 

 In some other cases a zone of green rocks (with diopside. dark mica, 

 amphibole, and green spinel) intervenes. Bands (sills) of granulite 

 of various width, down to less than a foot, may occur in the lime- 

 stone, and are parallel to the foliation and general strike. These 

 show peripheral transitions to the limestone by incoming of original 

 calcite and the appearance of lime-silicates, or are separated from it 

 by a zone a few inches wide, in which the minerals diopside, amphi- 

 bole, and green spinel are characteristic. 



Some interrupted sills are described, and compared with the 

 interrupted dykes of nepheline-syenite in the crystalline limestones 

 of Alno, described by Prof. Hogbom. A sill may thus be continued 

 along the strike as a series of lenticles. Elsewhere quite isolated 

 masses of pyroxene-granulite occur as inclusions in the lime- 

 stone. 



Although the relation of the granulites to the limestones is on the 

 whole intrusive, the two rocks in their present condition 

 are essentially contemporaneous, and seem alike to have 

 consolidated from a molten magma. The calcite occurring in the 

 granulites near the contact has all the appearance of an original 

 mineral. The foliation of the limestones is regarded as a sort of flow- 

 structure, and corresponds with that of the granulites to which it is 

 always parallel. That the foliation does not result from the action of 

 earth-movements on a solid rock is shown by this, that the very 

 minerals whose variable distribution is one of its chief causes, have 

 certainly not been affected by deforming earth-movements, nor are 

 they such as to have been produced by these ; moreover, in this 

 respect a distinction cannot be made between the limestones and 

 granulites, which would necessarily have suffered alike had they been 

 subjected to deforming strains since the consolidation of the latter, 

 The original nature of the limestones is less evident: they may 

 have been sedimentary or tufaceous, and, if so, subsequently 



