Town Geology; The Lesson Of The Philadelphia Rocks Studies Of Nature Along The Highways And Among…

Paperback | January 31, 2012

byAngelo Heilprin

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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. 1885. Excerpt: ... III. THE ROCKS OF THE SCHUYLKILL AND WISSAHICKON. You have, doubtless, observed in your rambles through the Park and elsewhere that the roads and pathways are in many places full of glistening particles, which appear like so many brilliants through the reflection of light from their tiny surfaces. Whence do they come? Examine such a particle, and you will find it to be a minute scale, either colorless or of a grayish-white tinge, sometimes quite dark, and more or less translucent or transparent. Some of the particles are very much larger than others, and in such specimens the judicious use of a knife-blade will frequently cause the separation of the apparently homogeneous scale into a number of distinct scales, each one to all intents and purposes identical with every other. This mineral, Mica, is a compound in principal part of silica, alumina, iron, and potash; it is the substance used in the windows of stoves, which is frequently, but erroneously, known under the name of " isinglass." If we carefully look over the rock masses lying around we will observe similar particles of the same mineral, here, however, not loosely scattered about, but firmly implanted in the rock surface. The mica forms a part, indeed a very large part, of the solid rock, and as such a constituent it enters either as the white variety, known as Muscovite, or the black variety, Biotite. In technical phraseology the rock is "micaceous;" wherever it occurs, we meet with those glistening particles on the roadside to which reference has been made. The logical inference is that these scattered particles have been derived from the solid rock, which through some process or other has been compelled to yield up its constituent parts. Our deduction is proved to be a correct one, for everywhe...

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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. 1885. Excerpt: ... III. THE ROCKS OF THE SCHUYLKILL AND WISSAHICKON. You have, doubtless, observed in your rambles through the Park and elsewhere...

Format:PaperbackDimensions:38 pages, 9.69 × 7.44 × 0.08 inPublished:January 31, 2012Publisher:General Books LLCLanguage:English

The following ISBNs are associated with this title:

ISBN - 10:0217297757

ISBN - 13:9780217297752

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