GEOLOGY. 279 



large crystals of feldspar, smaller crystals of quartz, and smaller flakes of 

 mica. Here and there hornblende appears. The rock bears no resemblance 

 to the sub-silurian Highland and Blue Ridge range and Adirondacks. It is 

 friable under the weather, shedding its crystals upon the ground under 

 every overhanging ledge. The boulders are rounded by the weather action 

 apparently more than by movement; for they have only travelled down the 

 slopes beneath the cliffs from which they have fallen, and where those that 

 remain are sharp-angled. The peculiar gravel and sand of the Mad River 

 valley is a local drift of similar origin. The metamorphism of these granites 

 is considered by Logan, Hunt, and: others, as no longer disputable. They 

 could easily originate in the clayey sandstones of Formations VIII., IX. and 

 .X., of the Appalachians. 



Considering the whole White Mountain mass a synclinal plateau, then the 

 summit of Mount Washington, which is such an acknowledged anomaly, 

 becomes regularly the single residual fragment of the highest formation 

 which escaped erosion. Its rock is so different in texture and structure 

 from the rest of the mountains that no other explanation seems possible; 

 and if this hypothesis be adopted, there is no longer any need of that which 

 supposes the submergence of New England up to the base of the head of 

 Mount Washington and no higher, leaving the head in the air to escape the 

 general rounding and polishing action. It becomes easy to consider the 

 external difference due rather to the difference of the rock formations above 

 and below that horizon. 



THE HIMALAYA MOUNTAINS. 



The brothers Schlagintweit, who have recently returned to Europe from 

 an exploration of Thibet and Napaul, Asia, state that they succeeded in 

 reaching the summit of Ibiganuri, one of the Himalaya Mountains, 22,260 

 feet high, which is the greatest height ever attained on any mountain. The 

 peak lately called Mt. Everest, of the Himalaya chain, is the highest moun- 

 tain in the world at present known, being considerably over 29,000 feet 

 above the level of the sea. The natives have two names for it one of 

 them, Gorishanra, which is mythological, is to be found only in the Nepaul- 

 ese, and the second name, Chiugofanmara, is that by which it is known 

 among the people of Thibet. 



ON THE CONDITIONS OF SILICA AND THE FORMATION OF GRANITE. 



The following is an abstract of an important essay recently published in 

 Pogyendorffs Annalen, which has excited no little attention among European 

 scientists, as it tends to the denial of the prevailing theory of the igneous 

 origin of granite. According to M. Rose's observations, there are two 

 different states or conditions of silica, one having a specific gravity of 2.6, 

 and the other varying from 2.2 to 2.3. The silica or silicic acid, with the 

 density of 26, is only found in the crystalline form, or in a compact form 

 more or less crystallized, while that with the lower specific gravity is always 

 amorphous. The properties of the regularly crystallized and the compact 

 crystalline forms are similar, and differ from those of the amorphous 

 varieties. M. Rose observes, that no one can doubt that compact crystal- 

 lized silica, such as is found in fire-stone, for example, has been formed in a 

 t way. lu petrified wood we often find the vegetable structure accu- 



