Page:A Treatise on Geology, volume 2.djvu/238

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224
A TREATISE ON GEOLOGY.
CHAP. IX.


A few detached basaltic cones appear near Egra, amidst the Fichtelgebirge. A much larger volcanic tract begins in the Mittelgebirge, and extends parallel to the Erzgebirge, and across the Elbe to near Zittau. The line of this system is continued by many detached cones across the range of the Riesengebirge into Silesia.

Volcanic appearances are mentioned near Ho north of Olmutz.

In Hungary, as described by Beudant, the effects of extinct volcanic action are extensive and remarkable. Five distinct groups of mountains, composed wholly of trachyte, are enumerated by Beudant, who attributes to each group a separate origin. One of these groups, larger than that of the vicinity of Clermont, being 20 leagues long, and 15 broad, is situated in the porphyritic mining district of Schemnitz and Kremnitz; another, smaller, but similarly circumstanced as to the porphyry, crosses the Danube, near Grau; another, extending east and west elliptically, forms the mountains of Matra, near Eger; the fourth, a large mass, ranging north and south, for 25 or 30 leagues, from Tokai to Eperies; the fifth is the group of Vihorlet, east of the last, apparently related to the trachytic mountains of Marmarosch, in Transylvania. Most of the Hungarian volcanic rocks can be classed as varieties of trachyte, according to a method of M. Beudant; opal, opalised wood, pearl-stone, and pumice, and scarified masses, abound; and from the porphyries of earlier date, there appears to be an easy mineral gradation to some of the trachytes. The latest volcanic action is placed by Mr. Lyell in the Meiocene tertiary period. The subjacent strata are mostly of the transition æra. Another group of Hungarian volcanos adjoins the Flatten See, on the north-west side.

In the eastern part of Transylvania volcanic rocks of tertiary æra occur in a range of hills covered with thick wood, extending from the hills of Kelemany, north of Remebyel, to the hill of Budoshegy, 10 or 12 miles north of Vascharhely. The principal