THE GREAT SCANDINAVIAN OVERTHRUST 409 



the Lapland Railway, I was enabled to spend a few hours at 

 Kaisepakte, where the thrust plane is most accessible/ 



A bluff of rock here rises steeply above the southern shore 

 of the lake ; the lower part of the slope consists of a massive 

 pink granite. Then follows a series of brown nodular shales, 

 with some layers of conglomerate ; next a green shale and a 

 brown nodular shale with some concretions ; then follows a 

 bed of dark blue massive quartzite. The shales are normal 

 sedimentary rocks resembling in aspect some of our Tarannon 

 shales. A fossil has been found in them at Luopahta, a few 

 miles farther to the east. Holmquist ^ quotes an opinion based 

 on it that the beds are of the age of the Chasmops Limestone 

 (Middle Ordovician) ; but the fossil appears to be indeterminable, 

 though its presence encourages the hope that better material 

 will reward further search. Above these Lower Palaeozoic 

 sediments comes a sheet of cataclastic schists, some of which 

 still retain the characters of augen-gneiss ; but the main mass of 

 rock has been broken down into a mylonite. This shattered 

 rock has been named " Kakarit " by Svenonius. All stages of 

 mylonitisation may be seen, including crushed gneiss, banded 

 felspathic quartzite, and banded granulites ; the extreme stage 

 in the dynamo-metamorphism is reached in some fine-grained 

 pseudo-phyllites, which look like simple slates. 



The overthrust rocks are intensely crushed and contorted, 

 great blocks being composed of layers twisted into complex 

 folds and overfolds. The underlying sediments, on the other 

 hand, often remain horizontal or with a dip of only 2°. Examina- 

 tion of this section is convincing that the crystalline rocks that 

 form the bluff of Kaisepakte have been thrust over the unaltered, 

 undisturbed underlying sediments. The descriptions by Dr. 

 Holmquist of the adjacent districts to the south of Tornetrask ; 

 by Tornebohm ^ of the country to the north of the lake 

 at the head of BalsQord, to the south-east of Tromsoe ; by 

 Sjogren of Sulitelma; and by Holmquist of the country south 

 of Sulitelma, show that this overthrust traverses the whole 

 length of Norrbotten, the northernmost province of Sweden. 



' During my visit I had the benefit of the company of Herr Ljiistrom and Herr 

 Sundius of Upsala. 



* Holmquist, Geol. For. Fork. vol. xxv. p. 38. 



^ A. E. Tornebohm, " Om formationsgrupperna inom det nordligaste Skan- 

 dinavien," Geol. For. Fork. vol. xxiii. pp. 206-17. 



