644 STRATIGRAPHICAL GEOLOGY. [Boox VI. 
Malvern Hills, a ridge of crystalline hornblendic rocks has been classed 
as of Pre-Cambrian date.1 In the Wrekin Mr. Allport? has found a 
nucleus of rhyolitic lava with rhyolitic agglomerate underlying 
quartzite, which according to Dr. Callaway is’ older than the Lingula 
Flags.2 Ancient as these volcanic masses are, they present remarkably 
perfect spherulitic and perlitic structures. Lastly, from amid the 
Triassic plains of Leicestershire rises an insular area of rocky hills com- _ 
posed of various crystalline rocks, which by the Geological Survey haye 
been classed as altered Cambrian, by Messrs. Hill and Bonney as pro- 
bably of pre-Cambrian date.* They consist of three great groups, among 
which volcanic agglomerates and tuffs form a large part. It will be 
observed that in all these tracts of presumed Archean rocks in England 
and Wales, lavas and volcanic detrital masses are especially prominent. 
No evidence of any contemporaneous volcanic materials has yet been 
detected in the extensive Archean tracts of Scotland. 
Scandinavia.—In Scandinavia,° Archean rocks (Grundfjeldet, Urge- 
birge) occupy extensive areas. ‘They consist chiefly of gneiss, but 
include also quartzite, quartz-conglomerate, quartz-schist, hornblende- 
schist, mica-schist, limestone, dolomite, with granite, pegmatite, amphi- 
bolite, garnet-rock, syenite, gabbro, labradorite-rock, olivine-rock, serpen- 
tine, &c. No general order of succession has yet been determined, though 
a clear arrangement into distinct zones is in many places observable. 
Thus in Rukedal (Southern Norway) a mass, 3900 feet thick, of quartzite, 
quartz-schist and interbedded seams of hornblende-schist, lies upon a 
group of hornblende-schists and grey gneiss traversed by abundant 
granite veins. Thin bands of limestone occasionally occur in the gneiss, 
as near Christiansand, where they have yielded many minerals, especially 
vesuvianite, coccolite, scapolite, phlogopite, chondrodite, and black spinel. ~ 
Apatite with magnetite, titaniferous iron, hematite, and other ores forms 
a marked feature of the Norwegian Archean series. The same rocks 
range into Sweden, where a red gneiss is found in the western, and 
a grey gneiss in the eastern districts. The former has been observed 
overlying the latter. The youngest division of the series consists of fine- 
grained to compact eurites or hilleflintas, with bands of crystalline lime- 
stone. Granite and other eruptive rocks abound. ‘The most important 
mineral masses in an industrial sense are thick beds and lenticular 
masses of iron-ore (Dannemora, Filipstad, &c.). 
Central Europe,—F rom Scandinavia rocks presumed to be Archean 
range through Finland into the north-west of Russia, reappearing in the 
north-east of that vast empire in Petchora Land down to the White Sea, and 
rising in the nucleus of the chain of the Ural Mountains, and still further 
south in Podolia. In Central Europe they appear as islands in the midst 
of more recent formations. Among the Carpathian Mountains they pro- 
1 Holl, Quart. Journ. Geol. Soc. Xxi, p. 72. 
2 Op. cit. Xxxiii. p. 449. 
® Op. cit. xxxiv. p. 754; xxxv. p. 643; xxxvi. p. 536. 
* Hill and Bonney, Q. J. Geol. Soc. xxxiii. p. 754; xxxiv. p. 199; xxxvi. p. 337. 
* Keilhan, “ Gaea Norvegica,” ili. (1850). Kjerulf, “ Udsigt over det Sydlige Norges 
Geologi,’ Christiania, 1879 (translated into German by Gurlt, and published by Cohen, 
Bonn, 1880). A. KE. Térnebohm, “Die Schwedischen Hochgebirge,” Schwed. Akad. 
Stockholm, 1873, “Das Urterritorium Schwedens,”’ Neues Jahrb. 1874, p. 131. Karl 
Pettersen, Geologiske Undersdgelser inden Troms Amt, &c., Norske Videnskab. Skrift, vi. 
44; vii. 261, 
