TIIK AKCH^EAN ROCKS 67 



arc quartzitic schists on the border of a large area of granite which 

 much resembles the post-Kalevian granites of Finland. 



Here it may be remarked that all the areas occupied by these 

 older Archaean rocks are invaded by large tracts of granite, most of 

 which are older than the succeeding Jatulian and Jotnian Series. 



The typical Jatulian is found in the east of Kiul.uid and in 

 Olonetz. It rests with marked unconformity on the Kalevian, 

 though itself consisting principally of white quartzites with bands 

 of epidiorite. At or near the base are conglomerates containing 

 rolled pebbles of granite, gneiss, and older vitreous quartzites. The 

 Jatulian quartzites often show ripple-marks and desiccation -cracks. 

 Above them are dolomitic limestones and shales (or slates), and in 

 several places beds of anthracitic coal occur. The total thickness 

 is about 2000 feet. 



Whether there are any rocks of Jatulian age in Sweden is a 

 matter of doubt Sederholm regards the Dal formation, which 

 occupies an area to the west of Lake Venern, as Jatulian, but his 

 only reason is that the beds are strongly flexured and affected by 

 pressure-metainorphism. Dr. Tornebohm dissents from this view 

 and maintains that the Dalsland Series is Jotnian, the petrological 

 resemblance being very close and the succession very clear, as given 

 below : 



Feet. 



I. Schistose grits, grading into mica-schists .... 1800 

 '5. White quartzite, with some beds of red slate .... 1600 

 -'. Dark slates with intercalations of earthy limestone and red 

 sandstone, and two or three sheets of schistose greenstone 



( = altered basic igneous rock) 2600 



1. Reddish quartzitic sandstones, with beds of arkose and con- 

 glomerate at the base 650 



About 6000 



The typical Jotnian is a great red sandstone formation which 

 has a great development in Central Sweden and Norway, extending 

 in a nearly continuous band from the area near Lake Mioeen to 

 the extreme north-eastern end of Finmark, a distance of about 

 860 miles. It may be regarded as including the Sparagmite sand- 

 stone of Norway, though, where the two come together, the la: 

 overlies the Jotnian with a certain amount of unconformity or 

 contemporaneous erosion, but the time value of the break does not 

 seem to be greater than that between the English Keuper and 

 Bunter, so that they form parts of one and the same system. 

 Each part of the series is over 2000 feet thick. 



To the east of the overthrust areas the Jotnian sandstones are 

 quite unaltered and lie in nearly horizontal sheets. At the base 



