Final Report, Band 7

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Seite 161 - That the rocky formation of this district, including the gneiss, the hornblende, and mica schists, the magnetic iron ore, and the quartz-feldspathic rocks, are of metamorphic origin there can be but little doubt ; consequently it is conceived that they were originally deposited by water in a horizontal position; that they are composed of materials derived from pre-existing rocks; and that they were subsequently disturbed in their position and altered by metamorphic agencies, which have caused them...
Seite 18 - The yield of the State during the past century is shown in the table below, which is essentially that printed in the Annual Report of the State Geologist of New Jersey for the year 1908. It is estimated that the total yield of the State since the beginning is in the neighborhood of 22,000,000 tons. The fluctuation in the amount of ore produced in recent years is graphically represented in figure i. Table VI. — Production of Iron Ore in New Jersey, 1790-1908. Year.
Seite 128 - AND EASTERN ONTARIO. A comparison of the geology of the New Jersey Highlands with that of the Adirondacks and Eastern Ontario reveals the fact that the Franklin formation and the Byram, Losee, and Pochuck gneisses have their equivalents in the northern districts, and that in general the three districts are essentially similar. The oldest rocks in the northern districts are crystalline limestones, quartzites, and micaceous schists that are considered to be metamorphosed sediments. Beneath these and...
Seite 175 - If it cannot yet be decided whether the Highland gneisses are sedimentary the supposed structural divisions of Britton and Nason can be regarded as only lithological. Britton's arrangement of a massive group in the cores and schistose groups on the outer parts of the ranges can be as well explained, as has been repeatedly seen, by the eruptive theory of the origin of the series as by the sedimentary. From Nason's work it appears that certain varieties of rock have a continuous widespread distribution...
Seite 121 - 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 169 - ... deposition was long continued, forming thick beds, when they in turn were covered by other sediments. Thus the accumulation went on as the older strata gradually and slowly subsided until the thickness amounted to thousands of feet. The time was long, perhaps as great in length as the combined ages of all the later formations. With the subsidence of the beds, the agents. pressure, heat and water, came into action, producing the great changes wherein these fragmental sediments and fine deposits...
Seite 125 - 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 169 - As already stated, the folding took place along northeast and southwest lines, and the lateral forces pressing the strata together was from the southeast side. But it is scarcely conceivable that such prodigious energy, exerted however slowly, confined itself to the folding in one uniform direction throughout the whole area of these Archean rocks. The elevating forces may have acted very unequally and at greatly varying rate; and the inequalities thus caused, with differences in the nature of the...
Seite 159 - 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." (P. 132.) A large number of mines were enumerated and details of their geology were given, and a summary of the...
Seite 124 - ... 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 associated...

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