Geology and Mineralogy. 395 



been reduced by this same denudation to heights of little more 

 than 3000 feet. Dislocations of one, two and perhaps three miles 

 in amount, parallel in general to the Highlands (N.E. and S.W.) 

 have occurred in Paleozoic, Mesozoic, Cretaceous and Tertiary- 

 times. " Great strips of Triassic and Old Red Sandstone strata, 

 like those of Elgin and Turriff and Tomintoul, and of the line of 

 the Caledonian Canal, are found let down among the crystalline 

 rocks by the gigantic faults," and in the Western Highlands dis- 

 placements of several thousands of feet affect the older Tertiary 

 rocks. The great central valley of Scotland consists of Newer 

 Paleozoic strata faulted down between the Archgean and Older 

 Paleozoic of the Highlands on one side and the Borderland on the 

 other. Fissures, injected by lavas from the great Tertiary vol- 

 canic foci of the Western Isles and Antrim, cross the Highlands, 

 the central valley, the Borderlands of Scotland and the region of 

 secondary rocks in Northern England. 



The address of Prof. Judd is a very valuable contribution to 

 the great subjects of mountain disturbances and denudation, and 

 also to other topics connected with the geology of the higher 

 latitudes. J. d. d. 



4. Results of the fusion of pyroxene and hornblende minerals. 

 — The Geological Zeitschrift, volume xxxvii (p. 10) contains an 

 article, by Mr. Arthur Becker, entitled "Fusion experiments 

 with pyroxene and amphibole minerals, and observations on olivine 

 grains." The object of the experiments was to ascertain " whether 

 the crystalline system of these minerals was determined absolutely 

 by their chemical composition." For this purpose the author 

 fused a number of specimens of pyroxene and hornblende in a 

 furnace and kept them as near the melting point as possible for 

 from. 8 to 36 hours, and then allowed them to cool slowly. He 

 succeeded in obtaining in most cases an almost completely crystal- 

 line mass, the characters of whose crystals he carefully studied 

 with the microscope. Of the orthorhombic system, he treated 

 hypersthene, bronzite, enstatite and anthophyllite; of the mono- 

 clinic, augite and hornblende; and of the triclinic, rhodonite, 

 fowlerite, babingtonite and bustamite. 



The following are the results of his experiments. Although 

 not deciding with certainty whether the fused triclinic minerals 

 cooled in the triclinic or the monoclinic system, yet, in view of the 

 very great resemblance to the mineral in the unchanged state, he 

 infers that the original form is retained. As to the orthorhombic 

 and monoclinic pyroxene and amphibole minerals, the experiments 

 proved that, when melted and cooled under the conditions stated, 

 they " crystallize again in the same systems to which the original 

 minerals belonged; but that the members of the hornblende series 

 cool as augite." 



The hornblende from Wolfsberg in Bohemia yielded results of 

 especial interest. In the first experiments the fused mineral 

 exhibited in the glassy ground-mass numerous large brown-violet, 

 sharply denned augites, and a very large amount of small bright 



