This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1921 edition. Excerpt: ...group an increase of the bases oxide of lime and oxide of sodium, which would result from such assimilation of carbonates and chlorides as has been described. The combination of free oxygen with sulphur, carbon, sodium and other elements probably explains why oxygen is among the rarest of the gases ...
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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1921 edition. Excerpt: ...group an increase of the bases oxide of lime and oxide of sodium, which would result from such assimilation of carbonates and chlorides as has been described. The combination of free oxygen with sulphur, carbon, sodium and other elements probably explains why oxygen is among the rarest of the gases emitted from lavas and why these have so generally a reducing character. Few geologists have, however, been willing to assume that any considerable assimilation of country rock goes on in connection with the movement of magma, Loewinson-Lessing, Daly and Sederholm being exceptions to the rather general rule. It is pertinent now to inquire what the observations of geologists tell us concerning the manner of opening up a conduit through which magma contained in a subterranean chamber may be conducted to the earth's surface. It was the belief of Suess that in few cases does this take place through a fissure, but rather after the manner described by Daly, in which the gases issuing from the magma near its upper surface are there permitted to unite and so develop heat after the manner of a blowpipe. He says, "Owing to their high temperature they melt and stope their way through the overlying rocks, and thus force their way upwards." Elsewhere he has described the process as not unlike that by which a red-hot iron makes its way upward through a board. Barrell and Daly have developed this process of overhead stoping in special studies, and the parallel is drawn with the quarrying process of that name in use by miners. The hot gases fuse and assimilate portions of the roof-rock near pre-existing fissures and eventually quarry away blocks which, once detached from the roof, tend to founder in the magma. The source of the nitrogen which is...
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