| Show 0 oil 11 problems in the uinta basin V by prof earl douglass surface ind indications ns gils gilsonite onite 11 II in the fhe last paper the larger veins of gilsonite were described it is a lecog nihed fact that gilsonite and the other asphalts asp halts are the re sult of the evaporation and oxidation of petroleum we found that taking the estimates of eldredge as to the quantity of gilsonite in the few large veins which he studied and his estimates are apparently the minimum it would take a large amount of oil at least a quantity which cannot be ignored to form forin these immense veins in this article we were to begin the search to see if it is possible to discover the source of these veins and to ascertain when where and how under what conditions they were formed it is the legitimate business of the geologist to do this if possible and it is the course which seems to the writer far more likely to bring 6 the desired practical results in a new field than to start star t off at once in the search of certain typical structures which in many cases hav proven productive but have in many other cases prove unproductive in other fields with a different geological his tory and structure we have already given a number 0 of facts which sur gest structures that so far as I 1 am aware have not bee generally recognized here structures which do in many fields influence the concentration of oil and which also suggest an answer to one of the questions which were proposed in the last article regarding the manner of oc currance of the veins of gilsonite I 1 did not wish to give an opinion ominio n as to the significance of certain facts until more of the evidence was before batore the reader probably some have already anticipated the solution suggested by the facts the data referred to are those concerning the length of the veins their vertical position the fact that they exten extend d in certain directions and that they occur in groups and in par albel bands with spaces or zones of approximately the same width apparently as the bands between the zones the r mere drying out of the strata could hardly have formed these veins b or fissures for the veins in the manner in which they occur we will say more of this when we come I 1 to fo the discussion of fissures it was seen that the veins of the bonanza group occur principally in the heavy sandstones of the lower uinta I 1 and middle uinta deposits these beds have been besig aad in part at least and in a hazy hay Z and undefined manner t I 1 a as bridger it is not the wish of the writer to confuse or scare the reader with technical geological terms or with worthy discussions until i it t becomes necessary for the I 1 clearer understanding of the problems to be solved but ex Peri ence has shown him how extremely unsafe it is is without I 1 out the evidence of fossils or the certain identification of f beds eds both above and below a formation to correlate it with I 1 1 a discontinuous or distant formation 1 the typical bridger beds are in the bridger basin in in wyoming they have been divided on the basis of their fossil mammalian faunas faunal into a half dozen successive horizons they are rich in mammalian and reptilian fossils of the former probably over species have been discovered it is true that feet or more above the bottom of what is called the lower uinta here fossil mammals have been found which resemble those of one or two horizons or levels in the bridger basin so far as I 1 am aware no identifiable fossils have been collected in the lower or feet of the so called lower uinta there now seems hope that such will be collected and studied but a large amount of field work of collecting in laboratory study and comparison are necessary to identify correlate distinguish the divisions and map the various tertiary horizons which overlie the green river deposits AM LZ X 5 als aured green river filled with mith velnie ts of gilsonite about feet helow below the top of the formation the rock below Is in tough toi ieli dark crinkly oil shale chale which resists renis ts tt wen therin and fracturing tie the gent linan dr francke Is seen neen sitting nt at tue the junction of the tio kinds of ft rock south east and north of the uinta mountains until this is done we will avoid misunderstanding confusion and probable error by designating these beds by their local names cretaceous and tertiary formations in the uinta basin to get et an understanding 6 of the conditions in regard to the oil it will be necessary to become familiar with the different divisions of the cretaceous and tertiary deposits here below is a list of the names of the formations as they will be us used ed in these articles the upper are the youngest Z the lower the oldest TERTIARY upper uinta C of peterson middle uinta uinta B of peterson lower uinta uinta A of peterson upper green river middle green river lower green river Wlas wasatch atch cretaceous mesa verde mancos mowery dakota please get these fixed in your our minds right side up with care in trying to discover the source of the gilsonite we should be bein begin in with the sandstones and sands in which the larger dykes are found usually these deposits do not show strong indications of being impregnated with oil or asphalt here though it is probable that in places tests for oil can call be obtained if amounts sufficient to form forin these large larbre veins reins came from these sandstones it seems almost certain that they would be highly b impregnated b in places with oil or asphalt it is true that in some places low in the deposits the sandstones on both sides of the dykes are impre impregnated C bated but this saturation apparently comes from froin the veins reins rather than the veins from the saturated rocks the wei weight ht of evidence and opinion at present seems to be in favor of the belief that the greater part of the petroleum in the earth originated in usually of dark color which are arc or were rich in organic matter though some favor the theory that a large part of it ori originated in lime stones which were formed of the shells and other hard parts of animals in the latter case it is supposed that the soft parts of the ani animals nials have been entrapped and have formed the oil in the uinta formations here there is very little limestone and the sandstones and sandy though some that the upper uinta at least in part was deposited af afta t the veins were formed formerly these deposits doubt un edly covered the older uinta deposits to the southward te farther west on what is termed the reservation tufit lower part of the upper uinta has much more heavy bed ded sandstone and the next zone of gilsonite veins west we the bonanza group extend far to the northwestward cu cutca ting into these sandstones in the region of randlett duchesne and moffat but probably feather out in the softer overlying beds to the northward pe if the above explanation of the pinching out to cheit the northward be the true one it would solve the mystery of the absence of surface debris and animal remains in thea th 14 ei gilsonite as the veins did not open to the surface bu buty gl pinched out in the upper uinta this will be better una un agi 5 der stood after we have made a study of the behavior 0 of t t i rocks fissuring etc under strain J in the badland bad land deposits of the upper uinta of the chec eastern portion of the basin which lies in utah we do nota no find the type of a formation which impresses us as beina bein 1 the source of the great dykes of hydrocarbons it is tru true that farther to the westward on the reservation as v shall see later there are bands of carbonaceous shale whit in thin bands are almost made up of vegetable matter a ai these give tests for oil the sane san stones are also in many places saturated we will make one more quest and if we do not fi fai borth GILSONITE VEINS 7 7 7 L d times showing a few traces trace of organisms do not as a rule appear to be rich in organic matter these formations however change much from place to place and what is said of them here will ri rill not apply to the same deposits farther to the west they are undoubtedly river river flood plain delta marsh and lake deposits and therefore chan change chane e very much locally we will however discard the probability of the petroleum originating in these beds until we have made an effort to find a more inore obvious source the possibility that the oil originated in other beds or other localities and mi migrated 6 rated to these sands or part of them will be considered later tracing out Gilso origin origin let us now trace these dykes to the northwestward to see if we can find the origin of the gilsonite there as eldredge says they die out or feather out there in the region of the bonanza and cowboy veins where they have been worked the upper uinta has been eroded away but farther to the north it appears in badland bad land hills and southwest facing badland bad land bluffs or escarpments therefore in gracin tracing the veins to the northwestward we are really tracing them up into the overlying b upper uinta where the veins soon die out this feathe feathering ring out is probably due to the fact that so large a proportion ol oi these deposits is unconsolidated sandy clays which would take up the strain by movement of the particles rather than by fissuring if they ended abruptly we might infer note I 1 have not tested them myself but I 1 have heard it reported that the uinta sandstones here do contain some oil some strata below which seem adequate to furnish th thes amount of oil required we may make a more careful bearc searce in the uinta formations lt let us select some advantageous place in the north corti nor ti ern portion of the part of the banta uinta basin which lies ih A utah for observation we are standing on some bench or r mesa beneath our feet is the upper uinta and probably each formation enumerated above lies in succession deeper ai and deeper beneath our feet As we go 0 o to the southward wel we descend at long intervals a series of great steps or terra terraces ceso to the level of older and older deposits we come to where y the upper uinta ends in a line of cliffs south of herd we see it no more as it has been washed away and the middle uinta appears appear s still farther to the south this for fori i mation vanishes and the green river appears and the then in jin succession the Wh wasatch satch the mesa verde and the man cos cs if we could have photographs which had been taken J at intervals of a hundred years for a il million lillion years or more and if we had them combined in a continuous film and thrown on oil the screen we would apparently see these ter races or escarpments all be beginning inning farther to the south as ward and gradually receding toward the north each suc j one at different rates depending on the hardness or softness of the rocks and other conditions which accelerate or retard erosion the conditions being as above de described bed it will b bj seen that if w we e follow the formations which contain th gilsonite to the southward we will pass over their expose exposed edges and if the rocks are not covered up there should be an opportunity to trace these veins down into the green river if they extend downward into that formation we will follow the bonanza vein or the bonanza veins as they are now united to the southeastward over the undulating benchland to the brow of the short deep canyon which enters white river the bluffs here are capped by the lower uinta sandstones on the top of the bench the course of the veins is marked by occasional prospect holes As the veins have been covered by debris we draw a line with these prospect holes to see where they go over the rim of the bluff A little below the top we see fragments of gilsonite g we dig away the debris and find small veins of this material we dig farther and find that there are several veins with a general course anasto mosing or running into each other As it is often expressed the sandstone is shot full of veins we now go a little lower and follow a barefaced bare faced ledge or terrace of more rock to see if we can find signs of gilsonite or any clue to its origin little if any is found but we descend to a lower level and follow another ledge 1 V off R bot 4 1 41 sanda benr the top of the green aliver R ncr formation cut through cliffs ahoe tire glowver U uinta I 1 nta eiith ath vein eins 4 of gilsonite the unal tile the vein aiu comes over oer the hrom brov of tile the bluffs to the right of tile the cliff back ck here we find pockets and streaks of a black hydrocarbon which is undoubtedly the thing we are after we are now in the green river when we b get back ack to the line of the larger b vein we see several ve inlets cutting through the shale and extending upward toward the larger vein we the bluff to the then go a little farther along southeastward where there is an overhanging cliff of t capping sandstone and the sh ales are more bare we see the e latter again shot through with veins of gilsonite we 90 S still farther and see more of these andi and in places the ales look oily on the surface A little above where the are charu changing ging to sandstones ind there is a gilsonite ils onite vein running along the beding plane some of the rock is saturated with asphalt and oil cavities in the rock are partly filled with gilsonite which is sometimes associated with some other n mineral or miner als one feels that he is getting near the source of the I 1 mystery which has surrounded these veins of gilsonite A small portion of the dark sand or sandy shale w when h e n P t t into a test tube with chloroform suddenly turns the latter ter to an arnber amber or dark reddish brown color samples samp les of finer which split into thin when put in chloroform show a dark oil ring on top of the chloroform in testing for oil in this way one should pour the solution into a clean test tube as reflection from the shale in the bottom of the tube will show a dark ring sometimes the oil has been naturally filtered in its migration through certain kinds of rock and it is so transparent that one is doubtful whether it is an oil ring or not to be sure about it one should pour the solution on a small white porcelain dish and let the chloroform evaporate if there is oil it will remain on the dish as an oily residue if it is asphalt it will be dark and sticky and have a peculiar rank odor which one soon learns to recognize we descend the slopes carefully as they are steep and treacherous we examine the steep faced cliffs and in many places see small veins of gilsonite cutting the shale perpendicularly the rock now is nearly all of a or slaty nature and is quite uniform in color being on the surface a light greenish gray though darker bands are seen these are everywhere interesting and nearly everywhere avery where show signs of oil indeed it is doubtful if on one e could find a sample of rock here except at the weathered surface which would not give a test for oil these however will be more thoroughly described later in the next article we will see if other veins can be traced down into the green river formation note errata in article III dec 30 1921 page 9 column one fifth paragraph last line instead of compounds of hydrogen acid and oxygen read compounds of hydrogen and carbon in ath line from bottom insert often containing compounds between made and hig higher ber |
