On the Physical Geography of the Alps. 373 
the small beds of calc-tuff, often compose low terraces, behind 
which the crystalline rocks rise with steep ascents. Within the 
district under notice occur some isolated masses of limestone of 
considerable interest. Masses of gneiss, hornblende rock, and 
mica-schist, of different widths, form some not always very dis- 
tinct radiating groups, similar to such as are so frequently seen in 
the crystalline slates of the Western Alps. Detailed accounts of 
these rocks succeed ; after which we have the geology of the 
Tauern Alps in the Upper Moll district, preceded by a list of the 
geological authors who have treated of this Alpine “ group” (p. 
228 
The Tauern are a lofty chain of crystalline rocks, forming a 
part of the Rhztian Alps. Especially in the north of this range 
the Alps exhibit a great regularity, for here there succeeds a dis- 
trict of tolerably developed transition rocks, whereon the vast 
range of the northern limestone Alps in Salzburg and Bavaria are 
elevated. 
The composition of this extensive “group” is somewhat vari- 
ous. Gueiss and mica-schists predominate ; between these rocks 
occur great masses of chlorite:slates, of hornblende rock, of cal- 
eareous schists, and of calcareous mica-schists. Granite also and 
isolated patches of serpentine are found at many points. The 
geological characters of this district follow in considerable detail. 
-M. Adolph Schlagintweit, in chapter xi.* (pp. 235-273), dwells 
upon the Formation of Springs and their different Temperatures, 
and on the Geothermal conditions of different Alpine districts. 
He finds that :—1. In using the springs for the determination of 
the local temperatures of the earth, it is indispensable that, in 
arriving at comparable results, we direct our attention to the geo- 
logical formations and local conditions, on which the nature of 
the origin of springs is necessarily dependent ;—2. The origin of 
Springs is not only connected with the mode of stratification, but 
also, and that most intimately, with the general character of the 
tock formation ;—3. The fissures and porosity of limestone give 
tise to important. differences in the conditions attendant on this 
tock and on crystalline schists. In limestone the springs are rare, 
copious, and, coming through this rock from the higher districts, 
often issue with a much lower temperature than usually found in 
Springs flowing out at such a level;—4. The altitude at which 
the last springs can occur depends on the general elevation of the 
Mountain-mass; their distance from the mean altitude of the 
Summits and crests is greater in limestone ranges than in those of 
€rystalline schists of equal height. In Alpine ranges of similar 
geological formations this distance becomes far greater when they 
tise far above 9000 feet (French), where, owing to the formation 
Poggendorf’s Annal. der Physik u. Chemie. 
48 
~_ * Original icated to 
y communica 
Szconp Serres, Vol. XIV, No. 42—Nov., 1852. 
