PUBLICATIONS. 499 
often diverse types, have been grouped together by this means, and 
confusion has often resulted. 
This paper of Dr. Nordenskjéld’s forms a very important contribu- 
tion to our knowledge of the Archean rocks, and it adds new meaning 
to these abused terms. The Scandinavian peninsula has long been 
classic ground for Archzan studies, and nowhere is that formation 
better represented, or its problems more varied. Smaland is a Baltic 
province comprising three districts of southern Sweden, and it is about 
twenty-five miles distant from Christiania. The surface occupied by 
the rocks described is over 10,000 square kilometers. In this paper 
the halleflinta and porphyries are particularly described, and references 
are made to the preceding work of Eichstadt and Holst on the basalts, 
gabbros and other basic rocks. The term /da//eflinta is a very old one, 
and designated a gneissoid, opaque rock which accompanied the ores. 
It was afterward applied to all rocks with a compact structure. A 
complete summary of the literature on this subject is given, and the 
progress in the knowledge of the true nature of such rocks is also 
pointed out. They were long regarded as of sedimentary origin. In 
1877, Allport, in England, proved the Shropshire greenstones to be 
acid eruptives, and he was soon supported by the other English petrog- 
raphers. Rocks similar to the Smaland types were described by 
Irving in the copper-bearing series, by Williams in the South Mountain 
district, and by Sederholm in Finland. 
The study of the Smaland rocks was commenced by Nordenskjéld 
in 1889, and their eruptive origin first shown in 1892. In this area. 
occur four belts of the Aa/eflinta, each 60 to 100 kilometers long and 
to to 15 kilometers wide. ‘They contain neither glass nor microfelsite, 
and so cannot be classed as felsophyres or vitrophyres ; further, they 
are identical with the South Mountain rhyolites. The granites of the 
area are both coarse and fine grained ; the latter, or aplitic variety, grades 
into the Adleflinta, and it often contains dark basic patches. The 
porphyries occupy a position between the granites and the eovolcanics, 
but they are allied to both. The granophyres are closely connected 
with the Lénneberg eodacite, especially near Nashult, where the rock 
is rich in augite. Porphyritic dyke rocks occur in many places, but 
always in or near the halleflint areas. They are identical with the 
massive porphyries, and they represent the last stage of the eruption. 
They occur by the hundred close together and parallel, but always 
separate. 
