﻿102 NEW YORK STATE MUSEUM 



the " garnet-gneiss " as a complex mixture of igneous intrusives 

 and partly digested sediments. It contains remarkable angular 

 masses of amphibolite which seem to be torn off rather by a deep- 

 seated igneous mass than by mechanical flowage. 



A very important member of the complex is the time-honored 

 " iron-gneiss," a rock of granitic composition with grains of magne- 

 tite distributed through it, but never segregated in amount rich 

 enough to be of economic value. It is prominent in southern 

 Sweden and is believed to represent a granite magma whose dif- 

 ferentiation was so diffuse as never to have yielded an ore-body. 

 The particles of magnetite are rather more prominent than in any 

 of our ancient granitic gneisses other than such as the lean ores at 

 Lyon Mountain and at the Benson mines. Geologically, however, 

 the parallel is close. 



Breaking through the sediments and the leptites are, further- 

 more, great intrusive masses of granite with gneissoid foliation, con- 

 centric with the borders of the batholiths and with massive textures 

 at the center. When mapped in some of the areas, the sediments 

 and leptites look like relatively narrow channels amid an archi- 

 pelago of large islands of the intrusives. In these channellike belts 

 are found the iron ores of southern Sweden. 



Along the southwestern border with Norway, very coarse granitic 

 gneisses appear, strongly banded and sometimes with streaks of 

 amphibolite. They have " eyes " of feldspar an inch or more in 

 diameter, and very strongly remind the American visitor of some of 

 our old Laurentian gneisses. They were shown to us near 

 Trollhatten. 



Another feature of the Swedish Archean that is of especial inter- 

 est to the visitor familiar with Adirondack geology is found in a 

 series of basic intrusive masses which run north and south through 

 southern central Sweden and which swing westward as they pass 

 north and reach the Norwegian boundary. They are called hyper- 

 ites and are later than certain quartzites of the region. The rocks 

 are practically the same as the basic gabbros of the Adirondacks and, 

 like them, contain bodies of titaniferous ore. The most famous 

 of the latter, Taberg, was shown to the visitors. Its geology is prac- 

 tically the same as the many bodies known to us in Westport and 

 Elizabethtown, but Taberg is much larger than any of ours. 



Anorthosites appear in Sweden just as they do in the Adiron- 

 dacks and in the province of Quebec, but not on so extensive a 

 scale as in America. Exposures were shown to us on the north- 



