62 GEOLOGICAL MEMOIRS. 
formation of Schemnitz and Kremnitz may be regarded as a single 
magnificent elevation-crater. 
In preparing a sketch for a geognostic map of the district of Krem- 
nitz, he was struck by the circumstance that several rocks had the 
same local distribution, to the total exclusion of others, which again 
were united in other local groups (rock-districts), of which he distin- 
guished four, namely the districts of the granite, of trachyte, of sphze- 
rulite-porphyry (less correctly also named the tufa district), and of 
the tertiary sandstone. The first lies without the elevation-crater, 
and requires no further notice in this place. The two districts of the 
spheerulite-porphyry and the tertiary sandstones must, on the other 
hand, be combined in one, as it is impossible to carry out their super- 
ficial division, volcanic tufas having been observed to alternate in 
some places with sandstones containing brown coal. 
‘The two districts that thus remain, though originally established 
only for the immediate vicinity of Kremnitz, are found, by more ex- 
tended. research, to maintain their complete independence throughout 
the whole trachytic group. The domain of the spherulite-porphyry 
forms a single uninterrupted ellipse, occupying the centre, whilst the 
trachyte district presents a ring-shaped ridge, returning into itself, 
and in general overlooking the central portion. The great extent of 
its diameter, from five to six miles (twenty-three to twenty-eight miles - 
English), and the mountainous character of the interior, has prevented 
this arrangement from being immediately apparent. The Szitna near ~ 
Schemnitz, the Skalka, and the Klak near Kremnitz, the Sattelberg 
near Koénigsberg, are members of this group, rising to elevations which 
the porphyry never attaims. Who does not recognize in this arrange- 
ment an elevation-crater ? The mountain-towns Schemnitz, Kremnitz, 
and Konigsberg, lie on its inner declivity; Hlmnik, now so justly 
celebrated, is situated nearly in the centre; the two large masses of 
diorite, traversed by mineral veins at Schemnitz and Kremnitz, are 
placed nearly diametrically opposite each other. The ridge of gneiss 
and syenite which stretches across from Glashitten, through the 
valley of Eisenbach to Unterhammer, and is accompanied by quartz 
rock, greywacke-like sandstones, and compact limestones, assumes its 
place between the central part and the circumference, and belongs, 
from its considerable elevation, to the latter. 
For the exterior domain of the trachyte, the distinguishing rocks 
are trachyte and diorite, with trachyte-conglomerate ; for the district 
of the spheerulite-porphyry again, this rock itself including the mill- 
stone porphyry, then pearlstone and freshwater quartz are fully cha- 
racteristic. The last three are distinctly limited to the interior of the 
crater, and in the whole circuit of the ring-shaped trachyte district 
not one locality is known where they occur; as, on the other hand, 
the trachyte and diorite are entirely excluded from the interior. The 
analogy with the elevation-crater of Rocca Monfina in Italy, so well 
described by Abich, cannot be mistaken; only in the latter the por- 
phyry of the centre attains the greater elevation, in the case before 
us the surrounding trachyte is the higher. The extensive beds of 
freshwater quartz must be considered as a more recent formation, 
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