摘要:

AbstractThis is the story, mainly verified from contemporary documents, of the first recognition of the origin of a meteoritic crater. It sketches the subject's life and character, boyhood, young manhood and personality, and also mentions other mining ventures. It tells of the acquisition and exploration of Meteor (Barringer) Crater, the contributions of his associates, and the lengthy resultant scientific controversies.

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1964.tb01428.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

AbstractA discussion is given of preliminary results of an analysis of the Murray carbonaceous chondrite which fell September 30, 1950, 9 miles east of Murray, near Wildcat Creek, Kentucky. The object is a mechanical mixture of minerals formed under different conditions at different localities.

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1964.tb01429.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

AbstractThe Dominion Observatory's meteorite crater research program is reviewed, with brief outlines of the methods of investigation, the progress to date, and plans for the future. The results and implications of recent investigations at the Deep Bay crater, the New Quebec crater and the Carswell Lake structure are presented.At Deep Bay diamond drilling near its center has confirmed that Cretaceous sedimentary rock lies within the crater, indicating a minimum crater age of 140 million years. Analysis of deformed rock and gneiss breccia encountered in a drill hole one mile from shore suggests that the original crater diameter is about 31,000 feet, considerably less than first estimated.Preliminary results of a gravity survey and a new shaded topographical map of the New Quebec Crater are presented. After correcting for terrain and regional effects a residual negative gravity anomaly of 6 milligals is indicated. Integration of topographical irregularities shows that the volume of the rim of the New Quebec Crater is about double the volume of the crater below the surrounding plain.Gravity and magnetic results over the Carswell Lake structure are consistent with an impact crater some 19 miles in diameter, taking into consideration that its original deformed floor has been uplifted in response to isostatic forces. Fragments of gneiss having radiating strations characteristic of shatter cones, discovered in the area of central uplift, support the meteoritic hypothesis of origin for this structure.

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1964.tb01430.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

AbstractEvidence is presented for believing that a feature about 1.5 miles in diameter, discovered on an aerial photograph of the Pre‐Cambrian Shield near Parry Sound, Ontario, is another old meteoritic crate

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1964.tb01431.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

AbstractThe characteristics investigated to date of ten circular structures in the Canadian Shield have supported their origin by meteoritic impact.Seven, ranging in diameter from 3 to 20 km, have a simple crater form modified by erosion. The underlying rocks have properties where known, which include:1Low density.2Low, uniform magnetic intensity.3Fracturing, alteration and deformation of the regional gneisses intensifying towards the center with the development of a coarse, essentially monomict, autochthonous breccia.4Overlying of the latter within the crater by highly mixed, partly vitrified allochthonous breccia. This layer has coalesced and largely recrystallized to a lava‐like matrix in the larger craters.5Unrecrystallized fragments in all the breccias showing textures comparable with artificially produced shock metamorphism.The three largest craters (30 km diameter) show a first order modification of the simple crater form due to a central uplift of the basement gneisses. The properties outlined above are found in the annulus surrounding the central uplift. Gneisses in the latter decrease in megascopic deformation towards the center but show evidence microscopically of shock deformation. Examples of this family of common characteristics are mainly drawn from Brent (4 km diameter) and the two Clearwater Lake craters (20 and 32 km

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1964.tb01432.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

AbstractConsideration of the orbits of meteorites indicates that their inclinations to the ecliptic are small and may be neglected in many statistical treatments. With this assumption the variation in the rates of meteorite falls per unit area on the surface of the earth is derived for meteorite velocities of 15, 20 and 25 km/sec as a function of both ecliptic and geographic latitude. At low meteorite velocities the variation is small but for meteorites with average or above average velocity the rate of impact in polar regions decreases to 50 or 60% of the equatorial values.

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1964.tb01433.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

AbstractAn eighty‐five pound siderite found in the autumn of 1962 in the Parry Sound District of Ontario appears, on the basis of a small specimen, to be a medium octahedrite. It has a sharp sub‐surface alteration zone, and the microstructure indicates a history involving severe shock. The fall possibly occurred during the winter of 1

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1964.tb01434.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

AbstractAn iron meteorite weighing approximately 57 pounds was plowed up near Seymour, Webster County, Missouri, about 1940. The importance of the find was not recognized until the fall of 1963, when a small piece was sent to Harvard University. Externally the meteorite is irregular, showing no evidence of oriented flight. Structurally, it is a coarse octahedrite containing conspicuous large nodules of troilite, which are rimmed with schreibersite.

ISSN:0026-1114    

DOI:10.1111/j.1945-5100.1964.tb01435.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY