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Seite 13 - Sei., 2d series, vol. 32, pp. 208-209, 1861. The annual report of the State geologist [of New Jersey] for the year 1864, 24 pages, Trenton, 1865. Third annual report on the geological survey of the State of New Jersey for the year 1866, 27 pages, Trenton, 1867. Geology of New Jersey, 900 pages, 7 plates, 13 maps in portfolio, imp. 8°, Newark, 1868. [Appendix, pp. 721-870, by other authors.] Annual report of the...
Seite 117 - Laurentian gneiss. Messrs. Miller and Knight, however, have recently subdivided the Grenville series of Eastern Ontario into an older and a younger series which are described as being separated by an erosion unconformity. The younger series is correlated with the Huronian of the Lake Superior region and the older, for which the name Grenville is retained, is correlated with the sedimentary portion of the Keewatin series in the Lake region. The igneous portion of the Keewatin is represented by a spheroidal...
Seite 145 - All these rocks were referred to as exhibiting "violent dislocations, being displaced vertically, laterally, contorted, folded, etc. Their general strike is northeast and southwest, and their dip southeast. They are traversed by joints • • • and in addition to their distinct stratification • * • they exhibit planes of cleavage frequently at right angles to the plane of stratification.
Seite 113 - Graphitic varieties are also occasionally found that are very rich in this constituent. In a few places these varieties have been mined as a source of plumbago. The question as to the origin of the magnetite and graphite has not yet been completely solved. In some specimens these minerals are embedded in feldspar and hornblende and thus appear to be original. In other specimens, however, magnetite occurs in the interstices between the feldspars and the graphite, in plates wrapping around quartz grains....
Seite 113 - Quartz 32.85 Orthoclase, 7.23 Oligoclase (albite, 56.07 : anorthite, 3.43), 59.50 Other components 1.22 100.80 The Byram Gneiss. — The Byram gneiss is a medium to coarsegrained gray rock in its most characteristic outcrops. Its essential components are microcline, a microperthite, orthoclase, quartz, brown and green hornblende, and sometimes green pyroxene. The accessories are sphene, apatite, and magnetite, and sometimes biotite. In some varieties quartz predominates over the feldspars. In some...
Seite 147 - ... true veins of igneous origin, which implies that they extend to an indefinite length and breadth, that they differ in character from the rock in which they are situated, and have been formed subsequent to it. Such deposits do not usually coincide with the strike and dip of the strata in which they are...
Seite 116 - Ontario there is in addition a series of amphibolites which have a three-fold origin. Certain ones are considered to represent limestones that have been altered by invading granites. Others have been produced by the dynamic alteration of basic igneous intrusions; while still others have in all probability resulted from the recrystallization of basic, fragmental, volcanic material. All three processes have produced amphibolites that cannot be distinguished from one another either by appearance or...
Seite 113 - ... They are strongly schistose and in many places they exhibit every evidence of having been crushed. The coarser varieties grade into garnetiferous pegmatites, though it is probable that some of them are crushed sedimentary rocks. The quartz-graphite schists are fine grained, very schistose, dark-gray, friable rocks composed of quartz, biotite, muscovite, occasionally a garnet, and a considerable quantity of graphite, in some cases reaching' 3% to 4% of the rock's mass. The graphite is usually...
Seite 143 - ... of the hornblende or red felspar. " The first theoretical inference naturally suggested by the remarkable manner in which all the veins without exception occur, is that the strata of the formation were, in all probability, at a pretty steep inclination previous to their appearance between the rock ; for it is inconceivable how a forcible injection of fluid ore could enter a series of beds, lying in a nearly horizontal position, without in one case causing and occupying fissures transverse to...