286 T. W. E. DAVID. 
the extensive sills of Mount Venda in the Euganean Hills.’ G. 
V. Rath and others have at an earlier date described the same 
district.2, Topley and Lebour have described the Whin sill of 
Northumberland, which may be taken as the type of a sill ona 
large scale. According to the description given by the above 
authors the Whin sill covers an area of from one hundred and 
twenty to one hundred and thirty Km., and attains a thickness 
of eighty-four feet and upwards. It cuts obliquely across the 
planes of bedding, so that it has a vertical range of over 1,700 
feet. Sir A. Geikie has described the extensive sills of the 
Western Isles of Scotland.* 
In Australia Mr. E. F. Pittman has described some interesting 
rocks from Hill End, which from their close resemblance to the 
Mandurama and Tamworth rocks of this Colony, as regards mode 
of occurrence, I have no hesitation in classing as sills. He says, 
(op. cit. pp. 1—2), “The siliceous slates and sandstones appear to 
be quite unfossiliferous, but obscure impressions of spirifera, 
encrinites, and corals (/'avosites) are rather plentiful in the meta- 
morphosed conglomerates. This latter rock forms one of the most 
noticeable features of the district. In the physical peculiarities 
of its occurrence it somewhat resembles the diorites which are 
characteristic of the neighbouring gold-fields of the upper Turon 
(Sofala), standing out on the hill tops in huge rounded masses, 
and showing a somewhat bomb-like or concretionary structure 
when quarried. Here, however, the similarity ends, for the Hill 
End rock, on close inspection, is found to be free from hornblende, 
and consists of quartz and felspar crystals in a blue silico-felspathic 
1 Die Euganiien, Bau und Geschichte eines Vulcans, 8° 1877. 
2 Geognostische Mittheil. iiber die Euganiischen ape bei Padua, 
Zeitschr. Deutch. Geol. Ges. 1864, xv1., S. 461 - Taf. xv. 
3. On the Intrusive Character of the Whin Sill of ‘saline: a 
Quart. Journ. Geol. Soc. 1877, xxx11., pp. 406 - 421. 
4 Trans. Roy. Soc. Edinburgh (1888) Vol. xxxv., p. 111, and Q.J.G.8., 
Vol. Lu., 1896, p. pp. 373 - 
5 Annual Report De aomikibncn of Mines, Sydney, 1879. Notes bad 
accompany Geological Map of Hill End and Tambaroora. 
