Vol. 56.] LIMESTONES PROM KATBTAWAE, ETC. 563 



more than 250 feet above sea-level, so that the maximum vertical 

 thickness of the Junagarh Limestone probably exceeds 200 feet. 



The larger structure of the rock is well seen at the Uparikot in 

 two deep wells, which can be descended by spiral steps cut in the 

 rock ; but a more extensive section is available in the quarries on 

 the northern side. The limestone is divided nearly horizontally 

 by planes 3 or 4 feet apart, which mark decided breaks in the 

 deposition. Between these the laminati6n is very oblique and 

 is cut off abruptly, both above and below, by the major divisional 

 planes. On either side of such a plane the inclination of the 

 lamellation is usually different, and the direction may either remain 

 the same, or be varied or reversed. The usual direction of the dip 

 of the laminae appears to be to the east. The inclination may be 

 anything up to about 30° with the horizontal, and may vary from 

 point to point of the same division of the rock ; but on the whole 

 the structure is fairly regular, in fact rather more regular than in 

 most false-bedded strata. 1 Similar structure is seen, though not 

 so well, in the quarries south-east of the city at the foot of the 

 Girnar Hills. 



I carefully enquired of the quarrymen whether they ever met 

 with anything in the nature of a fossil, and was answered in the 

 negative; nor was I able to find any object enclosed in the rock 

 larger than the grains of which it is composed. 2 



In hand-specimens 3 the limestone has a remarkable resemblance 

 to oolite, as the grains are mostly well-rounded and just visible to 

 the eye. Rocks of similar character from other parts of Kathiawar 

 were, in fact, described as oolites by the earliest observers. As will 

 appear from Mr. Chapman's paper, on microscopical examination 

 these rocks are seen to be mainly formed of organic calcareous 

 particles derived from shallow-water organisms of recent types. 

 Each particle is ordinarily surrounded by an envelope of deposited 

 carbonate of lime, the whole being bound together by a later 

 cement of the same material. Oolitic grains occur, but do not as 

 a rule show the structure well in thin sections. 



Interspersed through the mass are minute fragments derived 

 from the igneous rocks of the neighbourhood. They are, like the 

 calcareous constituents, cemented into the rock by calcite, but are 

 rarely surrounded like them by a true pellicle of calcium carbonate. 4 

 They seldom exceed 1 millimetre in diameter, and form only a 

 small proportion of the entire deposit. I have studied them both 



1 The section from the Forest Marble of Somerset figured by De La Beche- 

 [49] p. 536, and that of desert-sand in Prof. Walther's ' Denudation in der 

 Wiiste' [29] p. 519, are very similar in character, though not quite so regular. 



2 An occasional particle of igneous rock rather larger than the calcareous 

 grains was visible in places. 



3 Specimens, microscope-sections, and residues (after treatment with acid) 

 of these and other similar Kathiawar rocks have been deposited at the Museum 

 of Practical Geology, Jermyn Street. 



4 The calcite-crystals of the cement are usually small in the immediate 

 neighbourhood of the inclusions, and at first sight sometimes have the ap- 

 pearance of an envelope round them. 



