Professional Paper - United States Geological Survey


Was andere dazu sagen - Rezension schreiben

Es wurden keine Rezensionen gefunden.

Andere Ausgaben - Alle anzeigen

Häufige Begriffe und Wortgruppen

Beliebte Passagen

Seite 57 - Reconnaissances in the Cape Nome and Norton Bay regions, Alaska, in 1900,
Seite 34 - Island, is a lake about a mile long and a quarter of a mile broad, which is entirely surrounded by a rock rim.
Seite 24 - Paleozoic rocks of veiy varied app'earance, and probably referable to several of the main subdivisions of the geological scale. In so far as the information obtained in the region here in question enables conclusions on the subject to be formed, the lowest part of the rocks (1) consists of greenish and gray schists, generally feldspathic or hornblendic, but often quartzose and including distinctly micaceous and talcose schists, with some bands of limestone, the lithological character of this subdivision...
Seite 14 - The two latter lie without the region under discussion, and will not be further considered. The so-called Coast range extends from near the boundary of Washington northward through British Columbia into southeastern Alaska. In British Columbia it has a width of about 100 miles, which decreases to the northward.
Seite 38 - The indications on the surface are that Prince of Wales island contains much mineral. Gold, both free milling and in sulphurets, silver, galena, copper, and iron have been found in many places, but as yet no extensive efforts have been made to demonstrate whether any of the ores mentioned exist in paying quantities. If minerals exist in other portions of the district the very limited prospecting done has failed to show it. Annette island may be an exception, and also Dall island. Some of the finest...
Seite 47 - Pegmatitic and aplitic rocks. . . . These have more the appearance of segregations than true injections. In thin section a specimen from one of these was seen to be composed essentially of orthoclase and plagioclase more or less idiomorphically developed, and containing many gas or fluid inclusions, together with allotriomorphic quartz. Muscovite occurred as an accessory mineral. Another occurrence of pegmatite typically developed. . . . Here a coarse, white, pegmatitic rock cuts the greenstone schists.
Seite 24 - Analogy with the southern portions of British Columbia which 1 have examined leads me to believe that the greater part of these volcanic materials are also to be classed as of Carboniferous age, but it is quite probable that here, as to the south, they comprise, as well rocks of similar appearance which are of Triassic age, but which we are at present unable to separate from them. This is further rendered probable by the occurrence, in certain black argillitcs at Glenora, on the Stikine, of Triassic...
Seite 24 - Fusulina, have been detected in some beds of this limestone series, probably belonging to its upper portion. Forms of the genus Fusulina are characteristic in certain zones of the Carboniferous limestone in California. They have been found by the writer in a number of places in British Columbia, which, with the discoveries here reported on, occur at intervals along a belt of country to the north-east of the Coast Ranges for a distance of over 800 miles. The limestone last-mentioned appears to be...
Seite 24 - These are associated with, or pass up into (3) black argillites oi' argillite-schists, also containing thin beds of limestone, which, at one locality on the Dease, have afforded a small number of graptolites of Cambro-Silurian age. Next above these is a series (,4) consisting chiefly of massive limestones, generally of gray or blue-gray color where unaltered, but often locally changed into white or variegated crystalline marbles.
Seite 81 - This volume is for in- library use only. It may not be charged out. Return this book on or before date due. !' .:' ./•••

Bibliografische Informationen