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ham, but the writer had never seen anything of equal perfection. 

 Our ancient gneisses are more coarsely crystalline. Orno is well 

 illustrated in reference (14). 



In the far north at the two iron-mining districts of Gellivare and 

 Kiruna we saw geological sections in some respects different from 

 anything mentioned above. At Gellivare, syenitic rocks are the 

 ones associated with the ore bodies and strongly remind one of 

 the walls at Mineville, and elsewhere in the Adirondacks. At 

 Kiruna we find an extended section from syenites below on the west, 

 through two thick sheets of porphyry, with the ore-sheet between 

 them, to a series of sediments and schists of various sorts which 

 constitute the eastern section and which remind one both of the 

 Huronian and the Keewatin strata of the Lake Superior region. 



With the above general review of the component rocks in mind, 

 we may grasp some of the larger features of the Swedish Archean. 

 The sedimentary rocks and the leptites appear in separated localities. 

 It is necessary therefore to treat them individually, just as our 

 New York geologists have of necessity first studied the Adirondacks 

 and the Highlands of the Hudson as distinct areas, and the Lake 

 Superior geologists have taken up one by one the several iron 

 ranges. Parallels may then be later drawn and correlations may 

 be established. The correlations are, however, necessarily based on 

 lithologic characters and on the parallelism of great unconformities 

 or periods of faulting. The igneous masses must in time be matched 

 by. their lithologic characters and mutual relations. It would lead 

 to too long and involved a discussion were we to attempt in this 

 paper to follow out the several areas. They must be studied in the 

 Swedish monographs and with maps in hand. In this way, how- 

 ever, the correlations have been elaborated. All Scandinavian geolo- 

 gists are not agreed upon the parallels which have been suggested. 

 It is easy to see, however, that in the nature of the case these 

 equivalents are largely matters of opinion rather than the results 

 of demonstration. 



The ordinary metamorphosed sediments of Sweden have many 

 close parallels in our Grenville strata, but the leptites are not known 

 with us. The granites, syenites, hyperites and anorthosites are 

 much the same on both sides of the ocean, but the peculiar rapa- 

 kivi type fails here. In New York and in the East in general, the 

 writer knows of no such remarkable interpenetration phenomena 

 as those seen in Sweden, but the Lake Superior region may con- 

 tain them. Notwithstanding the contrasts, there remained in our 



