Reviews — Dr. LansdeWs Central Asia. 329 



The next report is that of Dr. Robert Bell on the Sudbury Mining 

 District to the north of Lake Huron, now noted for the presence of 

 nickel and copper ores, which are extensively worked. The district 

 is wild, hilly, and rocky, and the glacial boulders are often piled one 

 on the top of another without any fine material between them. The 

 rock succession is : (1) Laurentian gneiss and hornblende granite ; 

 (2) Huronian quartzites, greywackes, and dolomites ; (3) Dark- 

 coloured siliceous volcanic breccias and black slates, overlain by 

 argillaceous beds and nearly black gritty sandstones probably of 

 Upper Hnronian or Cambrian age. The nickel and copper ores are 

 always found in intimate association with the greenstones, and 

 generally at their junction with some other rock. The microscopical 

 characters of the Huronian rocks of this district are fully described 

 in an appendix by Prof. G. H. Williams. 



Passing over Mr. A. J. Low's Eeport on the Geology of three 

 counties near Quebec, and of Mr. Hugh Fletcher on that of the 

 counties of Picton and Colchester, Nova Scotia, we find a lengthy 

 report on Natural Gas and Petroleum in Ontario prior to 1891 drawn 

 up by Mr. P. H. Brumell. Since the remarkable discoveries of 

 natural gas in the Trenton rocks of Ohio, numerous borings in 

 search of this product have been carried out in various parts of 

 Ontario, but the only area in which it has been found in any 

 quantity is that between Lakes Ontario and Erie, not far from the 

 Welland Canal. The gas occurs in a sandstone of the Medina 

 formation (Silurian), which is here from 800 to 900 feet beneath 

 the surface. The only petroleum-producing district in Ontario is in 

 the county of Lambton, and the oil is found in the Corniferous 

 limestone (Devonian) at depths from 370 to 480 feet beneath the 

 surface. The various borings have yielded an interesting record of 

 the distribution and depth of the Palseozoic rocks in Southern 

 Ontario, and they show a possible maximum thickness of 4200 feet 

 overlying the Laurentian gneiss. 



A considerable portion of part ii. of the volume is occupied by a 

 chemical contribution to the Geology of Canada by G. C Hoffmann, 

 and by the reports of mineral statistics and mines, which are mainly 

 of economical importance. 



The value attached by the Government of the Dominion to the 

 Geological Survey of the country is satisfactorily shown in this 

 Annual Eeport ; and we are glad to notice that it is published at the 

 moderate price of two dollars, or less than eight shillings, whilst 

 the particular reports, and the maps, can be obtained separately at 

 prices from sixpence to one shilling each. G. J. H. 



IV. — Chinese Central Asia: a Eide to Little Thibet. By 

 Henry Lansdell, D.D., etc. (With Three Maps and Eighty 

 Illustrations.) In Two Volumes. London : Sampson Low, 

 Marston, and Co. 1893. 



DE. LANSDELL'S adventurous journey across the western 

 end of Chinese Central Asia was undertaken in connection 

 with mission work, but his book incidentally includes a considerable 



