196 



PEOF. P. M. DUNCAN ON THE 



and shales and bands of limestone, highly coralliferous, are very 

 constant. 



The Gaj series rests conformably on the ISTari series; although 

 there is a mineralogical break, the passage is so gradual that cal- 

 careous bands of the Gaj series are found interstratified with the 

 uppermost Nari sandstone. The Gaj series overlaps the JSTari to the 

 south and rests on the Khirthars, and is wanting in Lower Sind to 

 the eastward of the Laid range. 



Korth-east of Karachi the series is highly developed, and massive 

 limestones occur ; they reach as far as the coast. 



The uppermost beds of the Gaj series are variegated clays and 

 grey sandstones, which form a passage into the everlying Manchhar 

 strata, and contain species of Ostrea, Corbula, Area, Scalaria, 

 Buccinmn, and Turritella. A crab of the genus Typilobus and the 

 Vicarya Verneuilii already noticed have also been found there. 

 The oyster is like Ostrea multicostata. The Echinoderms are of the 

 genera Maretia, Meoma, Breynia, Clypeaster, &c. The Corals found, 

 principally associated with the limestone-beds, are very different in 

 their aspect from those of the underlying JSTari group. They belong 

 for the most part to reef-building genera, and some are represented 

 in modern reefs by allied species, which grow in the surf and in the 

 most exposed parts. The rest were dwellers in quiet water. Great 

 masses of the coral limestone consist of StepJianocoenia maxima in 

 casts, and the presence of the genera Madrepora, Haliastrcea, and 

 Porites is very significant of shallow-water conditions. 



E.esting on the Gaj strata is the Manchhar group ; and where the 

 Gaj beds are wanting, and even where the Nari series is deficient, 

 this upper group rests on the Khirthars. 



Of great thickness (10,000 feet on the flanks of the Khirthar range) 

 the Manchhar series is divisible into an upper and a lower group. In 

 the lower group much grey sandstone, soft and fine-grained, and 

 composed of quartz with some felspar and hornblende, is found ; and 

 red sandstones and conglomeratic beds exist towards the base, as 

 well as red, brown, and grey clays. The conglomerates do not 

 contain pebbles of older Tertiary rocks ; but cream-coloured clay, 

 soft sandstone, quartzite, and micaceous shale are found in them. 

 The conglomerates near the base are ossiferous ; and the vertebrate 

 remains are teeth or bones more or less rolled. There is no satis- 

 factory distinction to be made on the Gaj river between the estua- 

 rine beds at the top of the Gaj series and the lowest beds of the 

 Manchhar ; and osseous remains have been found in the upper Gaj 

 series. 



The upper part of the Manchhars has a conglomerate in it with 

 stones derived from the older tertiaries ; below it are red, brown, or 

 buff sandstones, with some clays ; and there are no fossils. 



Although usually conformable to the Gaj series, in places the 

 Manchhars rest on the older rocks ; and there are proofs of the Gaj 

 strata having been greatly denuded before the deposition of the 

 Manchhars. 



In the Laki range the Manchhars have an ossiferous conglo- 



