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Judging therefore of the thickness of the conglomerate, as seen in the separate mountain-masses, I estimated it at least from one thousand five hundred to two thousand feet. These lower beds are traversed by several dikes of decomposing porphyry. The quartzose strata in one spot were folded into a regular dome.
Lieutenant Yusuf blasted the chocolate-coloured quartzose rock in four places, filled as many sacks, and struck the pilgrim-road in the Wady el-Mu'arrash, leaving its red block, the Hamra el-Mu'arrash, to the left. His specimens were very satisfactory; except to the learned geologists of the Citadel, Cairo, who pronounced them to be carbonate of copper! Dr.
It was then resolved, in case of any unforeseen invasion, to abandon the castle of San Antonio, after a short resistance, and to concentrate the whole force of the province round the mountains, which may be considered as the key of the Llanos. The top of the Imposible, as nearly as I could perceive, is covered with a quartzose sandstone, free from petrifactions.
The pebbles in these conglomerates are sometimes composed of granitic and quartzose rocks, sometimes exclusively of different varieties of trap, which last, although purposely omitted in the section referred to, is often found either intruding itself in amorphous masses and dikes into the old fossiliferous tilestones, No. 4, or alternating with them in conformable beds.
Some of the most remarkable occur a few miles from Liverpool, in the whitish quartzose sandstone of Storton Hill, on the west side of the Mersey. They bear a close resemblance to tracks first observed in this member of the Upper New Red Sandstone, at the village of Hesseberg, near Hildburghausen, in Saxony.
A lime-kiln formerly stood in a grass-field near Leith Hill Place in Surrey, and was pulled down 35 years before my visit; all the loose rubbish had been carted away, excepting three large stones of quartzose sandstone, which it was thought might hereafter be of some use.
The geologist's theory, combined with the knowledge that the noble metal is 'chiefly found among palæozoic rocks of a quartzose type, is practically valuable on the Gold Coast. Every mound or hillock of red clay contains one or more quartz-reefs, generally outcropping, but sometimes buried in the subsoils. They can always be struck by a cross-cut trending east-west.
The uppermost of these consists of ferruginous sands, the second of sands and clay, and the third or lowest of a brown clay, abounding in fossils. Pebbles of quartzose sandstone, jasper, and flinty slate, together with grains of chlorite and mica, and, as Mr.
Beyond the ferry the road crosses Emu plains, a level tract, here about a mile in width, and intervening between the river and the base of the mountains. This flat consists chiefly of gravel composed of large pebbles, for the greater part quartzose; and in sinking a well, a bed of them was found in which many were nearly spherical.
Pyrites dispersed in quartzose veins, crossing the mica-slate, are often auriferous, no doubt; but no analogous fact leads to the supposition that the sulphuretted iron which is found in the schistose marls of the alpine limestone, contains gold. Some direct experiments, made with acids, during my abode at Caracas, showed that the pyrites of Cuchivano are not auriferous.
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