Economic geology of the United States

The Macmillan company, 1905 - 435 Seiten

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Seite 79 - In the geological sense limestones are of sedimentary origin, while marbles are of metamorphic character, but in the trade the term marble is applied to any calcareous rock capable of taking a polish. In addition to the different varieties of marble and the ordinary limestones, there are certain kinds of calcareous rock to which special names are given, as follows : Chalk is a fine, white, earthy limestone, composed chiefly of foraminifcral remains.
Seite 72 - ... this phenomenon which is known as "fatigue in stone." This is the first attempt which has yet been made to show this property in stone and the importance of the results cannot, at this time, be estimated. Transverse Strength. — The force required to break a bar of any material one inch square when resting on supports one inch apart, the load being applied in the middle, is known as the transverse strength, which is measured in terms of the modulus of rupture. The importance of this determination...
Seite 441 - The majority of the Conference wish to impress upon the attention of the teachers the fact that there has been developed within the past decade a new and most important phase of the subject, and to urge that they hasten to acquaint themselves with it and bring it into the work of the school-room and of the field.
Seite 441 - There is an advanced and modernized phase of it, however, which the majority of the committee prefer to designate physiography, not because the name is important, but because it emphasizes a special and important phase of the subject and of its treatment. The scientific investigations of the last decade have made very important additions to physiographic knowledge and methods of study- These are indeed so radical as to be properly regarded, perhaps, as revolutionary.
Seite 210 - ... it under the valleys. Under some depressions it may even reach the surface and form springs or swampy conditions (see Fig. 131). The depth of the water table is quite variable, being but a few feet below the surface in moist climates, while in arid regions it may be 100 feet or more. FIG. 131. — Ideal section across a river valley, showing the position of ground water and the undulations of the water table with reference to the surface of the ground and bed rock. (After Stickler, UK Gevl.
Seite 105 - States are supposed to be represented by certain basin-shaped deposits of flint clay found in Missouri. USES OF CLAY. So few people have even an approximate idea of the uses to which clays are put that it seems desirable to call attention to them briefly. In the following table an attempt has been made to do this.* Domestic.
Seite 127 - States" (1905), p. 127. At the bottom is the main bed of rock salt, which is broken up into layers 2 to 5 inches thick by layers of anhydrite. Above this comes 200 feet of rock salt, with which are mixed layers of magnesium chloride and polyhalite. Resting on this is 180 feet of rock salt, with alternating layers of sulphates, chiefly kieserite, the sulphate of magnesia. These layers are about 1 foot thick. Lastly, and uppermost, is a 135-foot bed consisting of a series of reddish layers of rock...
Seite 322 - ... purposes, partly owing to its slight alteration in air, and secondly, because it can be rolled into thin sheets. In this condition it is used extensively for roofing and also for plumbing, and as a coating to iron this metal is extensively called for in galvanizing. It is also used for cyaniding gold. One of the most important applications is for making brass, which is ordinarily composed of from 66 to 83 parts of copper and 27 to 34 parts of zinc. The composition varies, entirely depending on...
Seite 195 - A red, transparent variety of corundum (A1203), having a hardness of 9 and a specific gravity of 4. The most valuable color in ruby is a deep, clear, carmine red. Rubies of large size are scarce, so that a 3-carat stone of good color and flawless is worth several times as much as a diamond of the same size. The best . ones come from Burma. In the United States they have been found in the stream gravels of Macon County, North Carolina, but the production is not a steady one. Those found in Arizona...

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