Reviews— Whitman OCross—Lavas of Hawaii. 89 
V.—Tue Kitonpixe anp YuKon GoLDFIELD. 
REPRINT from the Scottish Geological Magazine of a paper by 
Mr. H. M. Cadell on the Klondike and Yukon Goldfield in 1913 
is included in the Smithsonian Report for 1914 (pp. 363-82). The 
paper-is both of scientific and of economic interest. The absence near 
Dawson of the signs of glaciation so conspicuous to the south is 
explained by the extreme dryness of the climate. But for the 
destructive work of glaciers in the Ice Age placer deposits of gold 
might have been found in Canada, Scotland, or Scandinavia. At the 
present time mining in the Klondike needs ample capital. The various 
ways employed for winning the gold—uincluding the remarkable 
dredging process, and the hydraulic or ‘ monitor’ method—are fully 
described and illustrated. About a million pounds worth of gold was 
extracted in 1913. The life of the field has been stated to be very 
limited, but there is likelihood of the discovery of paying reefs. 
~ VI.—Txe Minerat Resources or THE Puinipprne Istanps FOR THE 
year 1914. Division of Mines, Bureau of Science, Manila, 
Philippine Islands, 1915. 
HE American administration of the Philippines has naturally led 
to a steadily increasing exploitation of the mineral wealth of the 
islands. Gold is by far the most important product, silver, iron, and 
lead following far behind. Deposits of copper, manganese, and coal 
have been worked from time to time, but have fallen into quiescence 
during recent years. Guano is now being mined as a fertilizer, and 
_ the War has reawakened interest in the manganese ores. A brief 
account is given of the occurrence of copper ores, associated with 
andesite, in Zambales. 
_ ViI.—Lavas or Hawatt and THEIR ReLations. By Warrman Cross. 
United States Geological Survey, Prof. Paper 88, 1915. 
HE author gives a full account of the petrography of the Hawaiian 
islands as far asthey are known at present. While the prevalent 
lavas are olivine basalts, many other types are represented, notably 
picrite basalt, bronzite basalt, trachydolerite, oligoclase-bearing lavas 
(e.g. kohalaite), soda-trachyte, nepheline basalt, and melilite basalt. 
This association indicates that the division of rock types into 
‘ Atlantic’ and ‘Pacific’ facies is inappropriate, and further that 
alkalic and calcic magmas may be derivatives from a common source. 
The lavas of Tahiti, Samoa, and Réunion illustrate very similar 
associations. The author discusses various processes of differentiation. 
He declines to admit Daly’s view that the more basic lavas tend to 
issue from lower levels than the lighter ones, and denies that the 
association of alkaline rocks with limestones has any bearing on the 
origin of the former. Beyond indicating that periods of decreased 
activity were favourable to differentiation, and stating his opinion 
that the processes appear to have acted mainly on the liquid magma, 
the author advances no suggestions as to the physical mechanism 
concerned. 
