GEOLOGY. 259 



AGE OF THE ALPS. 



SIR CHARLES LYELL, in his address before the London Geological 

 Society, after adverting to the almost conclusive evidence which now 

 exists in favor of referring the great nummulitic limestone formations 

 of the Alps to the eocene, or older tertiary, and not to the cretaceous 

 system, as was formerly done, makes the following interesting re- 

 marks : " To the English geologist, who remembers when the clays 

 and loose sands overlying the chalk, some of them containing shells 

 of species identical with those now living, were looked upon as very 

 modern, and as the creations of yesterday in comparison with the 

 rocks of the higher Alps, it may well appear a startling proposition to 

 learn that the clay of London was in the course of accumulation as 

 marine mud at a time when the ocean still rolled its waves over the 

 space now occupied by some of the loftiest Alpine summits. It will 

 follow, moreover, as a corollary from the same data, that not only the 

 upheaval of the Alps, but all the principal internal movements, dis- 

 locations, contortions, and inversions of the strata, are subsequent to 

 the origin of the nummulitic deposits, and had not therefore even 

 commenced till great numbers of the eocene, vertebrate, and inverte- 

 brate animals had lived and died in succession." 



SILURIAN FORMATION IN BOHEMIA. 



SIR R. I. MURCHISON, at the meeting of the British Association, 

 stated that the Silurian rocks of Bohemia, though occupying but a 

 small basin, 25 miles across, abound in fossils which exhibit an older 

 series of organic remains than any known in England. M. Barrande, 

 who has examined these rocks, has obtained from them 250 species of 

 trilobites, and this, too, after uniting many species heretofore consid- 

 ered distinct. Among them he has been able to distinguish sexual 

 differences and changes in the course of growth. 



THE TACONIC SYSTEM. 



AT the meeting of the American Association, at New Haven, Mr. 

 T. S. Hunt, of the Canadian Geological Survey, offered a communi- 

 cation, the object of which was to demonstrate the great similarity 

 which exists between the Green Mountain rocks and those of the 

 Hudson River group. The results of the Canadian survey have 

 shown, says Mr. Hunt, that the Green Mountain rocks are nothing 

 else than the rocks of the Hudson River group, with the Shawangunk 

 conglomerates in a metamorphic condition. The so-called Taconic 

 rocks are a series of sandstones, slates, and limestones, found at the 

 western base of the Green Mountains, and bounded on the west by the 

 Lower Silurian rocks of New York. Although similar in lithological 

 character to the rocks of the upper part of the Hudson River group and 

 the Shawangunk grits, they have been regarded by Prof. Emmons as 

 older than the Silurian formation, and breaking up through it. If 

 these supposed Taconic rocks are really an older formation breaking 



