454 Notices of Memoirs—Professor J. W. Gregory— 
some are altered sediments; and the view has therefore been held by 
de Launay and Vogt that the ores also are altered sediments. 
That ores are formed by igneous segregation of sufficient size and 
purity to be of economic importance is a theory which rests on two 
chief cases—the nickel ores of Sudbury in Canada and the iron ores 
of Swedish Lapland. 
2. The Sudbury Nickel Ores.—The nickel ores of Sudbury are the 
most important historically. They have been repeatedly claimed as 
of direct igneous origin by Bell (1891), von Foullon (1892), Vogt 
(1893), Barlow (19038), and by other geologists; and his view was 
advocated before the Association at the Johannesburg meeting by 
Professor Coleman. The theory was stoutly opposed by Posepny in 
1893, and Professor Beck in 1901 described some of the brecciated 
ore, and showed that its metallic minerals are sharply separated from 
the barren rock. He held that such ore must have been formed, not 
only after the consolidation of the rock, but even after or during its 
subsequent metamorphism. The views of Posepny and Beck seem to 
have been established by additional microscopic study of the ores 
by C. W. Dickson (1903). He has shown that the sulphides are 
separated from the barren rock by sharp boundaries, and without any 
indication of a-passage between them; that the fragments of ore in 
the rock have short corners, whereas, had they grown in a molten 
magma, the angles would have been rounded and the faces corroded. 
Most of the ore, moreover, occurs as a cement filling interspaces 
between broken fragments of barren rock and along planes of shearing. 
The Sudbury ores, therefore, appear to have been deposited from 
solution during or after the brecciation of the rocks in which they 
occur, and long after their first consolidation. If Dickson’s facts be 
right, the Sudbury ores are necessarily aqueous and not igneous 
in origin. 
3. Scandinavian Iron Ores.—The other important mining field of 
which the ores are claimed as of igneous origin is Swedish Lapland. 
Its ores are rich and the ore bodies colossal. One mine, Kirunavyaara, 
yielded over one and a half million tons of ore in 1906, and according 
to a recent agreement with the Swedish Government the annual out- 
put of ore from that mine may be raised to three million tons by 1913. 
The chief mining fields of Lapland, although situated to the north 
of the Arctic Circle, have long been known, for some of them contain 
veins of copper which were worked, for example, at Svappavaara in 
the seventeenth century. The iron ores, however, could not be used 
until a railway had been laid through the swamps of Lapland to carry 
the ores cheaply to the coast. In 1862 an ill-fated English company 
began a railway to the Gellivara mines, and thirty years later this was 
completed across Scandinavia, from the head of the Gulf of Bothnia 
at Lulea to an ice-free port at Narvik, on the Norwegian coast. 
This railway, the most northern in the world, passes the two great 
mining fields of Gellivara and Kiruna. The mining field of Kiruna 
is the larger and at present of the greater geological interest, as its 
structure is simpler and its rocks less altered. 
The ore body at Kiruna outcrops along the crest of a ridge two miles 
long, and it is continued beneath Lake Luossajarvi to the smaller but 
