304 J. W. JTJDD ON THE ANCIENT VOLCANO OF 



Carpathian chain, lencite, sodalite, nepheline, nosean, and haiiyne are 

 most ahnndant rock-forming constituents ; while on the sonth-east 

 of that mountain-range these minerals appear to be wholly unknown. 

 A glance at the ultimate analyses of series of the Tertiary volcanic 

 rocks of Hungary and Bohemia respectively will show that while 

 potash is an abundant constituent in the latter, it is present only in 

 very small proportion in the former. 



In no way, perhaps, will it be possible to make this contrast in 

 composition between the volcanic ejections of the two areas more 

 striking than by placing side by side the analyses of rocks from either 

 of them which contain nearly the same percentage of silica. I. is 

 the average of two analyses of Bohemian phonolites by Rammelsberg ; 

 II. the average of three analyses of Hungarian augite-andesites by 

 Doelter. 



I. II. 



Silica 57-05 58-75 



Alumina 21-57 17-02 



Oxides of Iron and Manganese 2-91 8-05 



* Lime and Magnesia 2-16 9-43 



Potash 5-89 1-26 



Soda 8-69 3-50 



We shall not here stay to discuss the interesting problem which 

 is suggested by these curious differences. Suffice it for the present 

 to notice the fact that while on the one side of the Carpathian chain 

 nepheline-, leucite-, and haiiyne-basalts with various phonolites were 

 building up the vast volcanos of Bohemia and Central Germany, 

 on the other side of that mountain-range andesitic lavas with some 

 rhyolites and felspar-basalts were being erupted on an equally 

 gigantic scale. In the two districts the volcanic activity began, 

 attained its climax of intensity, and fell into decline in correspon- 

 ding geological periods ; yet the products of the volcanic action in 

 the two districts are as different from one another as it is possible 

 to conceive. 



Since the extinction of the volcano of Schemnitz the igneous 

 forces have given rise to a number of minor symptoms. Hot springs 

 (probably forming gej T sers like those of Iceland and the Eocky 

 Mountains) have deposited enormous quantities of siliceous sinter 

 (freshwater ' quartz), which is found to yield at many points the 

 beautifully preserved remains of a flora not very different from that 

 existing at the present day. The localities of Ilia, Hlinik, and 

 Lutilla are particularly famous for presenting us with the relics of 

 this flora. Other springs, like those so abundant in Auvergne and 

 Central Italy, were highly carbonated, and have deposited enormous 

 quantities of calcareous tufa. 



Several hot and mineral springs still rise in the midst of the old 

 volcanic district of Schemnitz. Two of these, namely those of 

 Vichnye (Eisenbach), which has a temperature of 101° Fahr., and 

 Skleno (Glashiitte), with a temperature of 120° Fahr., have given 

 origin to locally famous bathing-places. At both points a consi- 



