113 REPORT — 1861. 



of igneous origin, was full of fluid cavities contained in tlio doubly acuminated 

 crystals of quartz for which this remarkable porphyry is distinguished. He also 

 showed doubly acuminated crystals of quartz m the saliferous gypsums of India, 

 both of which were full of fluid cavities, and the (quartz impressed with the gypsiim ; 

 and as no geologist would hold that this fonnation was of igneous origin, but that 

 the quartz, if not contemporaneous with the gj^sum, must have been subsequent, 

 and as the same phenomena were presented by the porphyry of Dun Dhu, he was 

 forced to the conclusion that it was as much aqueous in its origin as the saliferous 

 gypsum of India. The author exhibited a specimen of quartz which contained a 

 ciystal of iron pyi'ites, to which was attached a crystal of galena and also a small 

 massy zinc blende, while over these three metals was laid a covering of gold. From 

 this specimen he argued, that as all these metals were fusible at a much lower 

 temperature than quartz, they must have aggregated during a gelatinous condition 

 of the quartz ; and fiulher, that as the sidphides of the three metals were in chemi- 

 cally combining proportions, any heat which would have fused the quartz woidd 

 have made an alloy or a slag in which chemical combining proportions coidd not 

 occur. 



He also exhibited specimens of schorl which he had obtained in the granite of 

 Aberdeen, and drew the inference that schorl, which crackles and splits with a very 

 small increment of temperature, coidd not have been present dm-ing a molten con- 

 dition of the quartz ; and that it was crystallized prior to the solidifying of the 

 latter, as proved by tlie schorl impressing the quartz. The author, from a carefid 

 examination of the schorls in the quartzite of Aberdeen, was led to believe that the 

 quartz, while in the process of crystallization, expanded one twenty-fourth of its 

 bulk, a force which appeared to him to be suf&eient to cause all the upheavals and 

 disruptions which had led geologists to account for such phenomena by a molten 

 condition of the primary rocks. If this \'iew is coi-rect, and if the highest peak is 

 granite, as the lowest is known to be granite, the author calculated that as the 

 highest moimtain is only yf^ part of the radius of the earth, a thickness of the crust 

 of 168 miles is quite sulflcient to yield expansive force to raise the highest peak of 

 the Himalayan range. He fm'ther stated that the cause of the temperature at which 

 the fluids were confined being higher than the normal one, depended on the rise of 

 temperature which takes place during solidification. 



The author, in conclusion, trusted he would soon be in a position to confirm 

 these views when he had finished the investigation of the trap-rocks with which he 

 is now engaged. 



On the Laws discoverahle as to the Formation of Land on the Globe. 

 By the Kev. C. E. Gordon-. 



BestiUs of the Geological Survey of Tasmania. By C. Gottld, B.A., F.G.S. 



The formations treated of were the upper palaeozoic marine deposits and the coal- 

 measures. The apparent conformability of the two sections was shown, together 

 with their intimate connexion, serving to render their consideration inseparable. The 

 coal-measures exist to a greater or less extent throughout the coimtry referred to, 

 the depth being about 900 feet. The coal-measures of the district might be regarded 

 as constituting two distinct fields, the maximum one of which might be termed the 

 Mount Nicholas Coal-field, comprehending the various portions developed upon 

 either side of the Break o' Day Valley, while to the other the term Dou^as River 

 Coal-field might be applied, as indicating the area occupied by the carboniferous 

 formation between Long Point and Bicheno. In the first the position of the prin- 

 cipal seams of coal, although highly advantageous to their being worked, is at an 

 elevation of from 1200 to 1500 feet above the sea. There were at least six distinct 

 seams in the Mount Nicholas coal-field, one of which was of superior quality, and 

 12 feet in thickness. Ever since the discovery of the seam experiments have been 

 made, which, though amply suificient to prove the value of the coal for domestic 

 purposes and fc- application to the usual branches of manufacture, have been upon 

 too limited a scale to pennit of the determination of its value as a steam fuel. A 

 remarkable shale exists in the north of the islemd, available aa a source of paraiEne 



