﻿REPORT OF THE DIRECTOR 10,10 IOI 



nizable, were well on their way toward gneisses. The rolling out 

 and flattening produced by the great pressure were very impressive. 

 We have no parallels in New York but in the Lake Superior region 

 similar phenomena may be seen. 



Quartzites are at times well preserved, and while hard and dense 

 and obviously the results of extreme metamorphism, they are typical 

 cases of the rock. In the city of Vastervik they were shown to 

 the visitors in excellent exposures. 



Crystalline limestones and dolomites are important members. 

 They appear in the mining districts of southern Sweden and are 

 at times the wall rocks of important ore-bodies, as at Sala. The 

 excursionists saw them in a number of localities. 



Mica schists are also frequent rocks. They are associated with 

 the group of leptites. 



Leptite is a comprehensive name now largely used for the fine- 

 grained and banded or stratified rocks which are of great areal 

 extent in middle and southern Sweden and which, with the asso- 

 ciated sediments just cited, contain the ore bodies. Leptite, derived 

 from the Greek word for fine-grained, is not a name of a special 

 rock but of a group whose grain or texture is very small. The 

 varieties cover a wide range and have doubtless resulted from sev- 

 eral different original rocks. The halleflintes of the early writers 

 are included. They are flinty-looking rocks which consist of minute 

 quartzes and feldspars and are well known in the iron-mining 

 regions. Many more coarsely crystalline varieties than the exces- 

 sively fine halleflintes are also included under the term leptite, 

 although their grain is always minute. Generally speaking, the 

 leptites remind one of the Saxon granulites more than anything 

 elsewhere. They may be sheared and crushed effusives. They may 

 be consolidated and metamorphosed tuffs. They may be sediments 

 recrystallized to rocks of minute grain. Somewhat similar types 

 can be recalled in a few cases in America, but they are not common. 

 We have none in New York. 



Gneisses with garnet, cordierite, sillimanite and graphite are not 

 unimportant members of the great complex. They are believed to 

 be of sedimentary origin. They remind one strongly of some of 

 the gneisses of the Grenville series in the Adirondacks. Exposures 

 of the so-called " garnet-gneiss " a few miles east of Stockholm at 

 Fagersjo, which were reminiscent of some of the Adirondack rocks, 

 were shown to us. Though long regarded as sedimentary by the 

 Swedish geologists, there is now a decided disposition to consider 



