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By Joshua E. Clayton

This remarkable gold and silver bearing district is situated on the middle fork of Boise River, in Alturas County, Idaho Territory, about eighteen miles north of Rocky Bar, and sixty-five to seventy miles, as the crow flies, east of Boise City, the capital of the Territory. This district lies in the very heart of one of the most wild and mountainous regions of Idaho. For many miles in every direction nothing can be seen but bold granite mountains, with deep narrow gorges cutting into their sides in every direction, rendering them almost inaccessible except to .the hardy mountaineer and adventurous prospector. The mountain sides are covered, in most part, by dense forests of pine, fir, and spruce timber. In every canon there are clear streams of pure running water that empty into the principal forks of Boise River. The only line of approach to this mountainous region at present is from the southwest, by way of Rocky Bar, the county seat of Alturas County, to which place there is a good wagon-road. From thence to Atlanta City, eighteen miles, the road, or pack-trail, passes over the high, steep range that separates the south and middle forks of Boise River. During severe winters this line of approach is closed up by deep snows for months at a time, thus leaving the district isolated, in the bosom of the grand old mountains. The geological formation is granite, of a coarse, friable texture, and in many places is traversed by numerous dikes of syenite, and three or four varieties of porphyry, which cut through the granite in easterly and westerly directions. The metal-bearing reins also have an easterly and westerly trend, bat are occasionally intersected by the dikes. The largest number of the gold and silver lodes are confined to a

By E. P. Shea

The Anaconda Co.'s Geological Department at Butte, Mont., was started early in the Company's history because of litigation involving vein ownership and extralateral rights. The problems, some of which were resolved in courts, were many because of the large number of veins and lode locations. Defensive action was required to prove ownership and protect against illegal exploitation of the downward and extra-lateral extensions of the ore bodies. In many cases it was necessary to define the outcrop of the vein and to show that its apex was within the boundaries of the lode claim. Exhibits illustrating geology were needed to present the cases clearly, and these could be made only after careful inspection and mapping of the underground workings by competent geologists. Also, The Anaconda Co. was one of the first companies to recognize the worth of skilled mining geologists and the value of accurate records in the search for new ore. The department was organized in 1900 by H. V. Winchell who, with D. W. Brunton, worked out the methods. Reno Sales was Chief Geologist from 1906 until 1948 when he was succeeded by V. D. Perry, the present Chief Geologist. Under their direction, F. A. Linforth, M. H. Gidel, C. H. Steele, E. P. Shea, C. C. Goddard, Jr., and W. A. O'Brien enlarged the scope of the work and improved the technique.

Jan 3, 1961

By H. Vance

In 1932, as in 1931, the East Texas area outside the Gulf Coast exerted ' its influence over the entire petroleum industry. Practically 60 per cent of the oil wells completed in the United States during 1932 were in this area, development being chiefly confined to the East Texas oil field in Upshur, Gregg, Rusk, Smith and Cherokee counties. This East Texas area is geologically an interior salt dome basin, along the western edge of which are located the fault line fields as represented by Mexia and Powell. Production occurs on salt domes in the interior of the basin as represented by Boggy Creek and possibly Van, although no salt has actually been discovered in drilling at Van. Shore line conditions on the east side of this basin along the flanks of the Sabine uplift have been responsible for the East Texas oil field. Many known salt domes in the center of this basin have been tested but as yet have failed to produce oil in commercial quantities. The main producing horizon throughout the area is lowermost upper Cretaceous and is known locally as the Woodbine sand. The East Texas Oil Field Development.—Approximately 6000 producing wells were completed during the year in the East Texas oil field. No accurate estimate of the total initial production of these wells is available because few initial production tests were made as the wells were completed. The writer estimates the average initial production of these completed wells at 2500 bbl. per day while flowing wide open through tubing. Based on this estimate, the total initial production of the wells completed during the year is 15,000,000 barrels. At the close of 1932 there were approximately 9500 completed wells in the East Texas field. Of this number 176 were without pipe line connections. The oil produced from these unconnected wells could be marketed for $0.30 per barrel while the price paid for oil run from the connected wells was $0.75 per barrel.

Jan 1, 1933

By Edward Judd

CONSTRUCTION of the long projected Moffat tunnel, on the Denver & Salt Lake R. R., between Tolland and Irving, Colorado, is now actually and actively progressing. This 6.1-mile bore through the Rocky Mountains, at an elevation of about 9200 ft., will eliminate 33 1/3 miles of probably the most tortuous standard-gage track in the world, and at the same time will avoid the necessity for crawling over the snow-bound continental divide at an elevation of 11,660 ft Completion of the tunnel within the stipu-lated four years, is expected to nave an immediate effect on the develop-ment of the known coal fields in north-western Colorado, already penetrated at Craig, the present terminus of the road, while it will also enable the railroad to carry out the original designs of its founder, David H. Moffat, for through traffic from farther west. The intention now is to accomplish the latter object by an extension from McCoy following the canon of the Grand River down to a connection with the Denver & Rio Grande at Dotsero. Legal impediments to the financ-ing of the tunnel having been removed by action of the Colorado legislature in April, 1922, the Moffat Tunnel Improvement District issued bonds to the amount of $6,720,000 which have been widely and quickly distrib-uted through a New York banking house. Responsi-bility for the execution of the project has been vested in the Moffat Tunnel Commission, to which a board of consulting engineers has been appointed for carrying out the details of administration. This board includes D. W. Brunton and L. D. Blauvelt, of Colorado, and J. Vipond Davies and J. Waldo Smith, of New York; R. H. Keays, who has managed large tunnel projects in New York, is chief engineer for the Commission.

Jan 11, 1923

By G. G. Gunther, C. L. Boeke

THE zinc deleading processes at the Parral and Santa Barbara mills are described separately to provide a basis for comparison. Although the two procedures are fundamentally alike, there are some differences in application to meet specific conditions. The Asarco mill at Parral in the State of Chihuahua is a flotation plant treating 1450 metric tons per day of complex sulphide copper-lead-zinc ores. In general, the procedure used for selective separation of the minerals into a copper, a lead, and a zinc concentrate follows the usual practice. First, a bulk copper-lead concentrate is floated and then separated into a final copper and a final lead concentrate by the sulphurous acid process. A small tonnage of high grade gravity lead concentrate is tabled from the bulk copper-lead cleaner tailing before it is reground so as to avoid undesirable over-grinding and sliming of this portion of the lead mineral. Next, a zinc concentrate is floated from the lead rougher tailing and, as described later, is separated into a final lead product and a final zinc concentrate. Finally, the zinc rougher tailing receives a strong scavenger float to remove all recoverable middling values for regrinding and return to the flotation circuits. The slime is separated from the scavenger flotation product, and only the sand portion goes to the regrind section. The minerals in the separated slime are extremely resistant to all methods of selective separation and pose one of the major problems awaiting solution. Nevertheless, the slime shows a profit when mixed with either the lead or the zinc concentrate, except when metal prices are very low, so it is accepted as a final product for lack of a more profitable method of handling it. In contrast, the minerals in the reground sands of the

Jan 1, 1953

By W. A. Tiller, W. C. Johnston

A theoretical analysis of alloy solidification in which the effective partition coefficient, k, of the solute is allowed to vary as a function of interface position is performed. A variety of solute distm'butions in the solid is predicted depending upon the functional dependence of k with interface position. Conversely, the variation of k with interface position required to produce a particular solute distributzon in the solid can be calculated. These preciictions have been tested by controlling the width of the momentum boundary layer in the liquid as a function of interface position with a rotating mugnetic field. One of the objects of controlled solidification is to utilize the freezing process for the preparation of crystals of specific materials containing a predetermined distribution of solutes. For example, a thermoelectric power generation material may exhibit a figure of merit, 2,' as a function of temperature, T, and solute concentration, C, as illustrated in Fig. 1. If we wish to use this material in a device between the temperature limits T1 to T2 a significantly greater efficiency will result from the device if the thermoelectric element illustrated in Fig. 1 consists of a range of solute concentrations appropriately located with respect to the temperature distribution rather than using a sample of constant solute concentration. For this reason and many others2 we are interested in programming and controlling the solute distribution in a single crystal

Jan 1, 1962

By W. H. Adams

Inasmuch as] the mining of phosphate rock and its transportation has so general a bearing on the great industries of this continent, entering as well into the problem of our trade with foreign countries, it may be useful to place on record the following list of localities from which certain products of a like nature are received by us in a business way, or in which we are interested more or less either by ownership or by competition. As a ready means of comparison, the percentages of the mine products and the deteriorating constituents are given : Coprolite (Cambridge).—This material is obtained from the Upper Greensand formation in Cambridgeshire. The phosphate runs from 50 to 60 per cent., and averages 64 per cent. It contains much carbonate of calcium, but little iron, in the ferric condition. The superphosphates manufactured from the material are permanent and little liable to a revert." They contain from 28 to 35 per cent. of soluble phosphate. Coprolite (Buckingham).—From the same formation as the Cambridge variety, and very similar in composition.. It averages 60 per cent. phosphate. Coprolite (Suffolk).—These coprolites are not so valuable for the manufacture of superphosphate as the two previous varieties, as the iron they contain is in the ferric state, and liable to "revert" the soluble phosphate. The phosphate varies from 48 to 60 per cent., but averages 54 per cent. They are of Tertiary formation. Coprolite (Potton or Bedford).—The average amount of phosphate in these coprolites is about 50 per cent. In some cases they may, however, run up to 60 per cent., and in others may not exceed 45 per cent. They belong to the Lower Greensand formation. The ferric iron frequently is as high as 4 per cent., and the alumina as much. Russian phosphate comes from the chalk, and occurs in carious rounded masses. It contains from 28 to 35 per cent. of phosphate, but may run up to 69 or 70 per cent. Curacoa phosphate is also of very high class quality, giving 80

Jan 1, 1890

No records have been found of coal in the old Spanish documents, although some mention of it probably exists in manuscripts. Coal was found in Mt. Diablo, in Contra Costa County, about five miles south of the San Joaquin River in 1852, but the first mine, the Teutonia, was located in 1858. The deposits are located on both sides of a high ridge, and vessels of 1,000 tons burden could ascend the river to the nearest point to the mines.1 In 1854, coal was found about four miles from Oroville, on the Feather River, in Butte County. Development work was started and in 1856 a mine was opened. From the description the coal was likely a variety of lignite and probably never amounted to anything commercially, as it does not appear again in the records 2 The more valuable mines at Mt. Diablo were opened in 1859 and 1860. By 1867 there had been 11 mines started and at that time five were in operation. The seam conditions were much disturbed and lack of knowledge of them caused much waste of effort and money. All of the coal excepting that used locally and in nearby towns, was shipped to San Francisco, and largely used for steam purposes. The first receipts were in 1861-6,620 tons. A railroad to the river had been constructed and opened in February 1866. The Corral Hollow field in Alameda County was found and prospected to a small extent in 1862. Two mines were opened but little work was done and the field was then abandoned. Good exposures were rare and the cost of underground exploration was then prohibitive. The Commercial mine produced coal in 1869 and 1870, but a fire in the latter year destroyed the tipple and communications to the mine. The Livermore mine was abandoned after 18 months operation in 1875 and 1876 and no other work was done here until the nineties. In 1867 Hyne reported the presence of coal in workable thickness, and of good quality, on the property of the Pacific Coast Petroleum Company,

Jan 1, 1942

By Daniel M. MacNeil, Raymond L. Presbrey, Carle R. Hayward

At the February, 1916, meeting of the Institute, a paper presented by Hayward and Raymond gave the results of a study on the effect of time in tempering medium-carbon steel, when the following conclusions were reached: It is not fair to consider the question settled when only three specimens were used for each treatment, but the results obtained indicate that for reheating quenched medium-carbon steel to temperatures below 500" it is only necessary to heat it through. Longer heating has little or no effect on the tensile strength, ductility, or hardness. At temperatures above 500°, increasing the time of treatment causes a slight falling off in hardness and tensile strength with a corresponding increase in ductility. In the discussion of the paper these conclusions were attacked and evidence was presented that seemed to throw doubt on their accuracy. The authors, however, showed that this evidence was based on high-carbon or alloy steels and no facts regarding medium-carbon steel were presented. During this study the heat treatment was carried out in a small electric resistance furnace. It held nine specimens, but when these were placed in the furnace the temperature was lowered to such an extent that 30 to 40 min. were required to reach the desired heat. The authors pointed to this as a weak point in the investigation and it seemed wise to supplement the research by work on similar steel but using a different method of heating. This has been done and the results are given in the present paper. The Rhode Island Tool Co. coöperated by furnishing the steel and turning the tensile specimens. The steel used in this investigation came in three bars 3/4 in. in diameter; analyses are as follows: Carbon. MaNGanese, Phosphorus, Sulfur Bar NUmber PeR Cent. Per Cent. Per Cent. Per Cent. 1 0.46 0.56 0.010 0.055 2 0.44 0.58 0.007 0.042 3 0.48 0.58 0.007 0.048

Jan 1, 1922

By John P. Goheen

Considerable work has been done in developing a pyrometer to measure the temperature of molten brasses, bronzes, and aluminum in the crucible. On account of the high melting points and the amount of zinc and sulfurous fumes given off from molten brasses, the conditions are somewhat severe for a thermocouple of standard design; but satisfactory results are obtained with a portable pyrometer, 3 ft. (0.9 m.) of connecting lead wire, and a special 5-ft. nickel-nickel chromium thermocouple, composed of rods 1/4in. (6.35 mm.) in diameter. The lower 12 or 24 in., as desired, may be made detachable so that new tips may be connected at little trouble or expense. The portable instrument need not be of the extreme high-resistance type, as the movable parts of the galvanometer of a lower resistance instrument may be better constxucted to withstand the continuous handling such an instrument receives. Platinum-platinum rhodium thermocouples, protected with porcelain and graphite tubes, have been used, but the lag in registering the temperature is too great. It has been found that the range of temperature for various brasses is as follows: Red brasses...............2200-2250" F. (1205-1234" C.) Yellow brasses............2250-2400" F. (1234-1318' C.) Bronzes..................2300-2550" F. (1260-1400" C.) A recent test with a portable pyrometer having a range of 2600" F. with a bare 1/4 in. heavy exposed couple 5 it. long and a handle attached at the upper end showed that the temperatures of molten aluminum under varying conditions in an oil-fired crucible furnace and one of the Simplex type were as follows: CRUCIBLE, OIL-FIRED FURNACE SIMPLEX FURNACE Temperature of metal in furnace....... 1540" F. (837" C.) 1530" F. (834" C.) Temperature in ladle after skimming at furnace......................... 1480" F. (805" C.) 1440" F. (784" C.) Temperature in ladle after skimming at floor near mold................... 1440" F. (784" C.) 1430' F. (778" C.)

Jan 1, 1923

By M. Albertson

The purposes of this statement are to define a problem that exists in regard to the estimation of developed petroleum reserves, to analyze the problem in an abstract manner, and to discuss it as an introduction to certain papers that follow. The problem is to devise and develop a suitable procedure to permit more accurate estimates of developed petroleum reserves. Part of the problem is to make such estimates available earlier in the life of any particular pool. The problem of securing more accurate estimates of developed petroleum reserves existed prior to curtailment of production. With curtailment, however, the problem became acute, some of the more prominent reasons being as follows: 1. The standard method of estimation depended on production-decline curves. This method is inapplicable while curtailment prevails and available methods arc insufficient. 2. The retarding influence imposed by wide open flow conditions upon overdevelopment is absent. Great losses of capital by overdevelopment can now occur before realization of the true situation occurs, or before effective steps can be taken to stop such wastage. This increases the need for early, accurate estimates. 3. Above-ground stocks have diminished and the equivalent of such supply tends more and more to be retained underground in the natural reservoirs. It becomes increasingly necessary to know accurately the amount of these stocks. To direct attention to an additional point of different nature: improved accuracy of reserve estimation can be obtained only by closer scrutiny of the factors that determine recovery. This examination and the resulting efforts to measure the effect of these factors in terms of ultimate recovery must tend to improve ultimate recovery. The statements regarding the acute nature of the problem also indicate to some extent the importance of the problem and the necessity of finding a solution. Developed reserves of the industry, and of individual opera-tors, are one of the great factors that properly should determine explora-

Jan 1, 1936

By S. R. Elliott

THE Spies mine is located in the eastern half of the northwest quarter of section 24-43-35, near the village of Iron River, Mich., and is operated by The Cleveland-Cliffs Iron Co. Speaking generally, the jasper hanging walls of most of the deposits in the Iron River district dip at a steep angle and are exceedingly strong, standing without caving, even after mining has been continued for years and after large excavations have been made. The ore is fairly hard and tough and contains no slippage faces. It occurs in large masses, which are often egg shape, with the smaller end down, and can be mined in, open stopes without the use of timber. The common system employed in the district is the shrinkage stope, or some modification of it. The Spies system was developed to utilize the advantages of the open-stope method and to avoid the disadvantages of the shrinkage stope. The Spies shaft was sunk to such a depth that the bottom, or third level, was in rock at a short distance below the bottom of the orebody, the shape and extent of which had been previously determined by diamond drilling. This is shown in plan and by the ore contours at the first, second, and third levels in Fig. 1, and in section in Figs. 2 to 7. In order to provide the necessary mills and raises, three parallel crosscuts were driven on 25 ft. centers on the bottom level. Drifts on the second and first levels were driven to the orebody and followed the foot wall in a southerly direction to the end of the ore. In crosscut 3, Fig. 1, raises 30, 40, 50, and 60 were carried up on the foot wall and holed into the second level, and were ultimately carried up and holed into the first level. These foot-wall raises carry the pipes and ladders, provide a means of ventilation, and furnish safe communication to all working places in the stope.

Jan 3, 1922

By James Humes

The active mines in the Park City district at the present time are the Silver King Coalition, Daly-Judge, Daly West, and Silver King Consolidated. Several other companies, such as the Daly, American Flag, Ontario, etc., are doing considerable development work. In the Silver King Coalition mines the ore is a replacement of a dark siliceous limestone bed, varying in .thickness from 18 in. to several feet. In places the ore has reached a thickness of 25 ft. This limestone bed lies within 100 ft. of the underlying Weber quartzite. There are other lime beds, similar in appearance to this one, in the Park City formation, which is approximately 700 ft. thick; but not one of them has been found to contain any traces of ore. Directly under and in contact with the ore-bearing bed is another, composed of gray lime well studded with dark concretionary nodules; and this one is an unfailing indication of the proximity of the ore-bearing bed. These ore deposits make out from or have connection with some one of the ore-bearing fissures, which were undoubtedly the channels for the circulation of mineral-bearing solutions. It is therefore proper to run prospecting drifts in the fissures, although they seldom contain much ore. As a general rule, drifting in the fissures is not costly. Mining and mucking cost from $2.50 to $4 per foot, and very little timber is required. There are instances, as in the Daly fissure in the Daly-Judge mine, where the expense of keeping drifts open in the fissure is so great that it has proved economical to make the drifts in the foot-wall rock and run crosscuts into the fissure at short intervals. In the Park City mines it is not easy to determine beforehand the best method fir extracting the ore from a newly discovered ore shoot in the bedded deposits. While we may get one dimension from the drift run in the fissure, that will not give us a correct idea as to the other dimensions of the orebody. The fissures here referred to have a N. 35" E.

Jan 1, 1915

RAYMOND M. Howe (author's reply to discussion*).-Dr. Unger states that magnesite will hardly supersede dolomite in fettling after a heat; that it is hard to believe a slag composed of oxide of iron containing about 6 per cent. of phosphorus is the active corroding, agent in a boil in a furnace; and that boiling cannot be said to be the result of the chemical action of a high-phosphorus slag on a basic bottom. These are well-established facts that no one would venture to question. The authors were misinterpreted in the statement that "in the summary, it is claimed that magnesite low in lime, or of greatest purity, ranks first in resistance to slaking," etc. On the contrary, the position has been taken throughout that while a low lime content is advantageous, the presence of several per cent. of iron oxide (an impurity), is necessary in order to confer the proper bonding and sintering properties in dead-burned grain magnesite to be used for furnace hearths. We cannot subscribe to the view that pure magnesia is no better fitted for a refractory than pure lime,' nor that the pure natural varieties of magnesite; such as Grecian or Washington, must necessarily be burned with silica and oxide of iron to produce a satisfactory material. On a small scale, pure magnesia has been satisfactorily used as a refractory in the form of crucibles. In the production of dead-burned grain magnesite from the Grecian or Washington mineral, iron oxide is added but the addition of silica is neither customary nor desirable. It is possible to manufacture brick of good quality from both the Grecian and the Washington material without adding either silica or iron oxide, providing they are burned at a sufficiently high temperature. This is regularly done on a commercial scale both in America and abroad when brick of. exceptionally high refractoriness or special purity are desired. The following analysis is of an English brick of Grecian magnesite which is extremely low in all impurities.1

Jan 6, 1919

By M. Amsterdam, F. Rothwarf, L. Muldawer

SILVER-cadmium near the composition AgCd shows three equilibrium phases. As with 13 brass, the high temperature phase is disordered body-centered cubic (8) and the low temperature phase has the ordered CsCl structure . However, there is an intermediate temperature phase which is hexagonal close-packed ((). In a recent paper, Speich and Mack' report on a study of the Ag-Cd eutectoid near the AgCd composition. Unfortunately, the phase diagram upon which they base some of their conclusions is incorrect. That diagram is taken from the Metals Handbook' and the error is that the 0 and ( phases have been interchanged. The Handbook gives the low temperature phase as hexagonal (designated 5) and the intermediate temperature phase as cubic ordered (designated . The error may be typographical or it may be one of confusion resulting from the use of 5, ,, and 0 for the intermediate phase in various papers. A careful search of the literature reveals that a number of authors have indicated the correct relative positions of the 13, 5, and 0 phases. The comprehensive work of Fraenkel and Wolf clearly stated that the high and the low temperature phases are either identical or are very similar. olander,' on the basis of electrochemical measurements, showed that the 13 phase is disordered and the 1 phase (designated 8" in his paper and in refs. 3 and 5) is ordered. Further work by Durrant5 using thermal and metallographic analyses provided a more precise phase diagram. A summary of these works was given by Hansen6 and shows the correct relative positions of the phases. Owen, Rogers, and Guthrie7 located correctly the upper two phases by X-ray diffraction. Their failure to find the low tem-

Jan 1, 1954

By David Segura

THE Huitzuco mercury deposits have been described by C. W. Vaupell,1 therefore the general information such as location, history, production, etc. will not be repeated here. The present owners acquired the property when the deep levels of the Cruz mine were flooded, and it was believed that a relatively large tonnage of low-grade ore and fills would be encountered in the flooded section, because of the early mining methods used in the Cruz mine. The mine was partly unwatered and about 187,000 tons of fills was pit-sampled in the San Cayetano stope. These fills average 2.4 kg. Hg per ton. During the period of maximum production at Huitzuco, the ores were sorted in the mine and cobbed into 3-in. pieces, which were treated in Scott furnaces. Large pieces of raw ore are found in the sinter, and it is indicated that both recovery and costs were not very satisfactory. Recent practice has been to treat the ores in closed retorts made of 10-in. pipes. Because of the presence of combined antimony in the mineral livingstonite (HgS.2Sb2S3) and considerable native sulphur, little or no metallic mercury is recovered in the condensers and a second retorting of the condenser muds is necessary. This makes the treatment of the ores expensive and tends to low recoveries of mercury. The principal costs of retorting are, in their relative order: (1) fuel, (2) low recovery of mercury, (3) replacement of retort pipes, (4) labor. METHODS TESTED Three series of experiments have been made, with the object of reducing the costs of recovering mercury and antimony from the ores, by: (1) wet metallurgical methods, (2) bulk roasting in large mechanical furnaces, (3) concentration to reduce the bulk to be followed by roasting in some mechanical furnace. The wet metallurgical methods did not appear feasible because of the high cost of the alkaline solvents used, and investigations of these were not carried beyond the preliminary stage.

Jan 1, 1938

By Paul Weir

DURING the past decade, methods of producing bituminous coal in the State of Illinois, which ranks third in production among the states in which bituminous coal is mined, have undergone great changes. From less than one million tons in 1923, the strip-mine production has gradually increased to a high of 11,725,870 tons in 1937. From a negligible amount prior to 1927, the amount of coal mechanically loaded underground had increased to a high of 28,374,362 tons in 1937. The amount manually loaded in 1937 reached a low of 12,332,023 tons. In this same year, this state ranked first in strip-mine production, also in mechanically loaded production. For this reason a study of the influence of mechanization on location of production in Illinois may be helpful in anticipating what may happen in other producing states. The reason for the changes in methods lies in the differences in costs of production. The Bureau of Research and Statistics of the National Bituminous Coal Commission has made public the following costs of pro-duction by various methods in the State of Illinois (district 10) for the last nine months of 1937: all mines, $1.7602 per ton; strip mines, $1.4319; mechanical loading mines, $1.7457; hand loading mines, $2.1793; all underground mines, $1.8703. These are weighted averages for the entire district. Inasmuch as production in 1937 was reported from 58 counties scattered over two-thirds of the area of the state and from five different seams varying in thickness from less than 3 ft. to as much as 12 ft., it is apparent that the location of production must be influenced by the extent of mechanization possible in the various producing counties.

Jan 1, 1939

By Charles E. Weaver

Discussion of the paper of CHARLES E. WEAVER, presented at the San Francisco meeting, September, 1915, and printed in Bulletin No. 103, July, 1915, pp. 1419 to 1427. MILNOR ROBERT, Seattle, Wash.-A year ago at this time, 12 wells were being drilled for oil in western Washington. Some excitement attended the operations; many thousand acres of land were leased to oil companies and stock was widely advertised. The location of the wells may be described by referring to the conclusions in Dr. Weaver's paper, in which the State is divided into four areas. In the area described first, which includes the Cascade Mountains and eastern Washington, where conditions are decidedly against the existence of commercial oil fields, no new drilling was reported. In the second area, the Puget Sound Basin, where conditions are unfavorable, but to a less degree, five wells were being drilled. The third region, covering certain parts of southwestern Washington, contained four drilling wells and several others projected or beginning operations, in spite of the absence of petroleum seepages. None of the wells mentioned is fully active today. On the western side of the Olympic Peninsula, along the Pacific Ocean, are three wells which have been the scene of operations for the past two to three years. The region they are prospecting contains seepages of light oils and is the fourth area described in the paper. The difficulties of transporting both men and supplies to the well sites have delayed operations and brought the costs up to high figures. The drilling of these three wells is interesting on account of the presence of oil in nearby seepages and its occasional appearances in the material penetrated. A. C. McLAUGHLIN, San Francisco, Cal.-The most important part of Washington is on the Olympic Peninsula. The geological conditions on the Peninsula are not similar to the conditions in California, and it would not prove to be a continuous belt of oil-bearing territory from there to here if oil should be found at either end.

Jan 12, 1915

By Z. F. Danes

Combination of gravity data and density logs makes it possible to determine the structural relief. Under a wide class of geologic conditions, the solution is unique, or limited to a single parametric system of solutions. As a useful byproduct, the method yields a new way to construct derivative maps, continue the field up or down, subtract regional anomalies, and perform smoothing. In the past, the problem of interpreting gravity anomalies in terms of structural geology was solved along two main lines: 1) A body of a certain shape and density contrast was assumed and the corresponding gravity anomaly calculated, analytically for simple bodies, graphically and/or numerically for more complex ones; then the computed anomaly was compared with the observed one, and the assumed shape corrected according to the differences between the two. 2) The anomaly is assumed to come from a warped interface between two media of different density; the relief of the warping is assumed small compared to the depth of burial, so that the structure can be approximated by a flat horizontal surface of variable density distribution. The first method is a standard technique, described in every text book on applied geophysics, and is well applicable, for bodies with predominant vertical dimension. The second one, probably first used by Tsuboi and Fuchida,' is mathematically more elegant. It applies to the fashionable field of integral transforms (Bullard and Cooper, 2 Tomoda and Aki, 3 Dean 4) and is useful mainly in cases when the vertical relief of the structures is comparatively small. 30th methods, tacitly or openly, assume a density discontinuity across the boundary of the two media, while within each medium the density is constant. However, the recent invention of the gamma-gamma

Jan 1, 1962

By Fred T. Williams

The Park City mining-district is distinctively a camp of few properties, 5,000 acres, or one-third of the entire district, being under the management of but three companies. As a rule, the ore-bodies lie deep, with no outcrop, except where erosion has formed the deeper canyons and gulches. Ontario canyon exposed the famous Ontario ledge, and Woodside gulch showed the first ore of the Silver King Coalition mine. The Quincy ore-bodies were first brought to light in upper Empire canyon, and Thaynes canyon was instrumental in aiding the prospector during the early days of the camp. There are 22 shafts which have reached a depth of at least 500 ft., ten a depth of 1,000 ft., five a depth of 1,300 ft., and two a depth of 2,000 ft. The amount of lateral development has been proportiorlally extensive, including six long tunnels, four of which are in 3 miles, with a fifth now being driven. The Ontario lower drain-tunnel is now more than 4 miles long. The formations are sedimentary, dipping about 30° NW. and N., and traversed by many fissures, dikes, and faults. The principal ore-bodies are found. associated either with the contact of the basal Ontario quartzite and the overlying limes, or on a quartzite stratum within the limes, or in the fissures, or along some of the porphyry dikes. The district covers the intersection of the Uintah and Wasatch ranges, which explains the existence of large folds and faults, and fissures of great length, width, and depth. In a general way, the geology of the district consists of a basal quartzite dome, which has been exposed by erosion at the Ontario property. The Ontario fissure lies entirely within this formation. Flanking this dome on the west, north, and east lie

Jan 1, 1912