422 Scientific Intelligence — Meteorology and Geology, 



M. Boiissingault concludes from some experiments on metallic sub- 

 stances, which have been exposed to the action of electric fluid, that 

 sulphur is always present in such cases. 



2. On Cleavage of Slate-Strata. — Professor H. D. Rogers gave 

 the Meeting of the Association of American Geologists, in April 1845, 

 an oral abstract of a paper by himself, on the direction of the slaty 

 cleavages in the strata of the south-eastern belts of the Appalachian 

 chain, and the parallelism of the cleavage dip with the planes of 

 maximum temperature. 



He prefaced his communication by a brief sketch of the researches 

 of Professor Sedgwick and Sir John Herschell, in relation to cleavage, 

 which prove that it is a structural condition in rocks, irrespective uf 

 their dip, and is the result of molecular forces developed in the strata 

 subsequent to their elevation and contortion. 



He then proceeded to a description of the direction of the cleavage 

 planes in the Appalachian chain. By the aid of a general section 

 and a diagram, it was shewn that, throughout the south-eastern 

 belts of the chain, and in the region of the metamorphic strata still 

 farther towards the south-east, the strata lie in closely compressed 

 anticlinal and synclinal folds, the medial, or axis planes of which, 

 dip at a steep angle almost invariably to the south-east, or some 

 point between the south and the east. Now, it is a general fact, 

 established by his own observations and those of Professor W. B. 

 Kogers, that, from Vermont to Alabama, the cleavage dip is likewise 

 towards the south-east, and therefore nearly parallel in direction and 

 steepness to the anticlinal and synclinal planes. This prevailing 

 parallelism of the cleavage surfaces to the belts of maximum crust 

 and fracture in the strata, is suspected by the author to obtain also 

 in other countries, and is regarded by him as having an important 

 connection with the mode in which cleavage has originated. 



He called attention to the circumstance, that the anticlinal and 

 synclinal planes constitute in these closely plicated strata, so many 

 parallel and steeply dipping belts of fissured and dislocated rock, 

 more readily permeable than any of the other parts of the mass, 

 to the intensely heated steam and gas, which he supposes to have 

 issued through the crust of the earth, while the folding of the strata 

 was in progress, as it now does to a less extent during modern earth- 

 quakes. The hot effluent vapours would impart their temperature 

 along the anticlinal planes ; and thus the whole body of the strata 

 would consist of a series of alternating belts of heat, or more pro- 

 perly of steeply dipping planes, alternately warm and cold. This 

 symmetrical and parallel distribution of the heat seems to bo precisely 

 that which ought to impart through the new polarities it would awaken 

 in the mass, a corresponding symmetry and parallelism in the planes 

 of maximum and miminum cohesion, or, in other words, the planes of 

 cleavage. The conjecture that they have been thus produced, finds 

 confirmation in some facts mentioned by Professor Philips, in his 



