This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1880 Excerpt: ...of the latter. In a word, we shall adopt the opinion that the rooks in question are only intensely metamorphosed products. But it is only right to state that there are other geologists who will not admit the possibility of these rocks having had a metamorphic origin. That Trappean and Plutonic rocks have been once in a ...
Read More
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1880 Excerpt: ...of the latter. In a word, we shall adopt the opinion that the rooks in question are only intensely metamorphosed products. But it is only right to state that there are other geologists who will not admit the possibility of these rocks having had a metamorphic origin. That Trappean and Plutonic rocks have been once in a state of partial fusion is allowed by both sides; the two schools differ in their explanation of the way in which the molten condition was brought about. In order to make the matter clear, it will be necessary to give a summary of the opposite opinions held on this subject. There is good reason to believe that the whole earth was once in a state of fusion, and, according to one school, it consists now of an external solid crust, within which a mass or detached masses of the original fluid material still remain in a molten condition. Taking this view of the constitution of our planet, some geologists will have it that all lavas are portions of this molten interior mass, which have been forced up to the surface, and that those rocks known as Trappean or Plutonic, which differ from subaerial lavas in being more compact and crystalline, are portions of the same molten interior mass which have cooled and hardened under pressure. This school, then, draws all igneous products from an internal permanently molten reservoir. But of late years a more careful examination on a large scale in the field of the rocks hitherto classed as Trappean and Plutonic has shown that they can be occasionally traced passing insensibly into foliated, or less highly metamorphosed, or even unaltered derivative rocks; and also that they occur now and then in masses of a bedded aspect among undoubtedly stratified deposits. These facts have led to the belief that such rocks h...
Read Less
Add this copy of Geology for Students and General Readers: Physical to cart. $69.32, new condition, Sold by Booksplease rated 3.0 out of 5 stars, ships from Southport, MERSEYSIDE, UNITED KINGDOM, published 2015 by Arkose Press.
Add this copy of Geology for Students and General Readers: Physical to cart. $69.86, good condition, Sold by Bonita rated 4.0 out of 5 stars, ships from Newport Coast, CA, UNITED STATES, published 2015 by Arkose Press.
