Show orl origin gl n of carioti Car te ores on april the new york section of the mining metallurgical society of america had for its subject of discussion radium the following remarks by frank L hess of the united states geological survey are taken from the may bulletin of the society the fields of the united states contain the greatest quantity of uranium minerals of all known deposits these lie in the high plateau region between the rocky mountains in colorado and the san rafael swell in utah practically all are south of the denver rio grande railway and as at present known the deposits extend just below the arizona line outside of this large area which includes the famous paradox valley and the adjacent areas in utah there are several localities where uranium ores occur in small quantities all lie in cross bedded sandstone which is probably of jurassic age HOW the great area of cross bedded sandstones originated has long been a problem my idea is that a shallow sea probably salt because there are few remains of animal life in the sandstones covered the whole area it was so shallow that the wind blowing for a long time in one direction would pile up the water at the lee end and many low islands and spits would be formed I 1 know of only two ways by which water laid cross bedded sandstone can be formed by deposition on beaches and by river bed deposition I 1 cannot imagine a river flowing through that country in such manner as to cause these deposits A remarkable feature of these beds is the presence of a tremendous quantity of fossil wood you find it everywhere in them the trees reach fifty or sixty feet in length and six feet in diameter they are all water worn exactly as you find the trunks of trees along rivers and sea coast today that proves that these trees had been floating in water and what is more natural than that the trees should have floated around in this sea lodged on the islands and been covered by succeeding layers of sands except in noncom non com mercial quantities deposits are found only with the fossil remains of these od trees and weeds two important facts are that the is found only with the wood and other fossil vegetation and we imagine the operators in the pack creek section near moab will take exception to this statement and many specimens of animal remains have been found also on the san rafael reefs near green river utah editor that in the deposits there is always an excess of vanadium though were alone present there would he be three times as much uranium as vanadium for convenient reference I 1 have prepared this table of uranium minerals KO K 0 cao buo unidentified cao bao cuo buo cao bao cuo buo cao 1 I believe that around these old seas were veins which were weathering away and the sulphuric acid thus formed from pyrite attacked the other minerals of the veins and carried the metals as sulphates into the shallow sea forming a very dilute solution from which on its coming in contact with the organic matter they were reduced to sulphides sulp hides and were deposited with organic material that is the reason we never find without vegetable remains most of the deposits are small because the patches of drift were of small extent A peculiar phenomenon is that some of the vanadium deposits contain selenium in elemental form in reply to a question mr hess stated that he had found none of these remains of vegetation and trees where vanadium alone had been deposited in the discussion that followed J F kemp said while mr hess was describing the sandstones in western colorado and eastern utah which make somewhat of a ring shaped series of outcrops I 1 could not help wondering whether they could not be interpreted as the terrestrial terr estial deposits partly windblown wind blown partly torrential partly the work of quieter streams this interpretation has cleared up a number of puzzling geological problems in the cases of other formations the great numbers of tree trunks rather coincide with this suggestion they might have come in upon streams at flood the radioactive radio active minerals are characteristic te of rather more than of any other form of deposit one cannot well avoid wondering again if were not present in the land area which furnished the sedimentary materials to the uranium bearing sandstones is commercially produced from a famous pegmatite dike at garda portugal and is found in remarkably fine groups of crystals for mineral cabinets as we all know has langbeen long been known in the gneiss es of philadelphia coating crevices in reply mr hess defended his theory on the ground that the sand grains under the microscope are exceedingly angular one reason for doubting that they were windblown he believed that had floods brought in the trees the evidences of cross bedding would have been largely obliterated there is no large gravel the largest being not over one inch in longest dimension |