OCR Text |
Show 55 content and the volume of the vanadium-bearing deposits, qualities that are intimately associated with changes in the bedding, the cross-bedding, and to some extent the grain size of the sandstone. The form of the .ore bodies also is Influenced by cross-bedding and the thickening and thinning characteristic of lenslng standstones. The mechanics of accumulation of the vanadium is not well understood, but the alinement of ore trends and orientation of "rolls" of ore and logs suggest stream channels, shore lines and related features. The cross-bedding is indicative of deltas and the tabular bodies could represent the flow of lakes or flood plains. Ore Deposits In a number of localities vanadium ore has been found in sandstone beds well below the top of the Salt Wash member of the Morrison formation, but the quantity mined from these lower beds has not been large. The vanadium deposits can be grouped, according to their general form, in two broad groups, rolls and tabular bodies- These forms, however, are not sharply defined, as one may grade into the other and there are numerous irregularities that defy classification. An ore body having an essentially sharp boundary that is conspicuously curved is called a "roll." The more typical forms are cigar-Jshaped, range in diameter |