, PART II

higher por t ions is possible t h a t Le of t h e P i e r r e jf 1,200 to 2,000 ay be developed ne, which is the

County , Colo. t he h ighe r por-

BITUMINOUS SANDSTONE NEAR VERNAL, UTAH

B y E . M . S P I E K E R

ABSTRACT

Asphalt Ridge, a series of low discontinuous hogbacks, 3 to 4 miles south­west of Vernal, Utah, contains beds of bitumen-saturated sandstone, most of which are of Eocene age and belong to the Uinta formation, but a few may belong to the Mesaverde formation, of Cretaceous age. At seven localities along a strip of outcrop about 11% miles long the thickness of the bituminous beds was measured and their relative richness estimated. Samples collected from one locality were analyzed chemically and mechanically to determine the character and quantity of the bitumen and the distribution and proportion of the various sizes of the sand grains. The analyses showed that the bitumen content of the sandstone ranges from about 8 per cent to a little more than 15 per cent by we'ght. On the basis of these data and the assumption that the mining can be carried back 1% miles from the outcrop it is estimated that the whole area examined should contain about 1,175,000,000 cubic yards, or about 1,970,000,000 tons, of bituminous rock. Of this amount 1,030,000,000 tons is in one tract about 2% miles long at the northwest end of Asphalt Ridge. The bituminous sand has been successfully used as it is mined for paving the streets of Vernal. The bitumen may lend itself to hydrogenation so as to yield motor fuels and related products.

I N T R O D U C T I O N

A s p h a l t R i d g e , sou thwes t o f V e r n a l , U t a h , h a s l ong been k n o w n to con ta in beds o f b i t u m e n - b e a r i n g sand a n d sands tone , which , a s sugges ted by t h e n a m e g iven to t h e r i d g e , h a v e been cal led a spha l t rock. Chemica l e x a m i n a t i o n of t h e m a t e r i a l shows t h a t i t i s no t t r u e a spha l t bu t m a y m o r e p r o p e r l y b e des igna ted b i t uminous sands tone .

I n o rde r t o d e t e r m i n e r o u g h l y t h e a m o u n t , ava i l ab i l i ty , a n d gen­era l s t r a t i g r a p h i c re la t ions of these beds , t he w r i t e r m a d e a br ief reconnaissance e x a m i n a t i o n of A s p h a l t R i d g e in Sep tember , 1926. No deta i led m a p was m a d e , b u t a n u m b e r of locat ions on the out­c rop of b i tuminous s ands t one were p lo t t ed on t h e m a p of t h e reg ion m a d e in 1907 by Gale . 1 T h e ou t c rop of the b i t u m i n o u s sands tone was fol lowed t h r o u g h o u t i t s ex ten t , a n d de ta i led sections were meas­u red a t several locali t ies.

1 Gale, H. S., Coal fields of northwestern Colorado and northeastern Utah : U. S. Geol. Survey Bull. 415, pi. 21, 1910.

77

78 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 193 0, PART II

PHYSICAL. F E A T U R E S OF THE A R E A

Location.—The area described is in northeastern Utah, west of the mouth of Split Mountain Canyon of the Green River (see fig. 2) , south of the Uinta Mountains, in the eastern part of the Uinta

I L/+° 113° 112° Lli! 110° ! °9 l

M4° H3° 112° lll° no° 109°

25 O 50 IOO MILES ' ' I ' l l 1 1 1 I

FIGURE 2.—Index map of Utah showing location of Asphalt Ridge

Basin. Asphalt Ridge occupies parts of T. 4 S., Rs. 20 and 21 E., T. 5 S., Rs. 21 and 22 E., and T. 6 S., R. 22 E. Salt Lake meridian, Utah.

Surface features.—Ashley Valley (see fig. 3) is flanked on the southwest by a line of hills and hogbacks, 200 to 900 feet high and about 14 miles long, known as Asphalt Ridge. This ridge, a distinct

BITUMINOUS SANDSTONE NEAR VERNAL, UTAH 79

topographic feature, trends northwest with fair regularity. The front of the ridge facing Ashley Valley is steep and is indented by the short gulches of intermittent tributaries of Ashley Creek; the other side slopes southwestward at moderate angles and is deeply in-

-&u&oog-snovcnrfajg u&citf/j o

trenched by long, winding gulches tributary to the Green River below the mouth of Ashley Creek.

The northwestern half of Asphalt Ridge, the highest part, is a prominent landmark. (See pi. 7, A.) The southeast half is lower and except for two or three buttes that rise 100 to 200 feet above the

76S48°—31 6

80 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 19 3 0, PAM* II BITt

main ridge is not a conspicuous surface feature. (See pi. 7, B.) Near the southeast end of the ridge the south side slopes off rather steeply toward the Green River, and the gulches there are deep and rough.

Settlement, accessibility, and roads.—Ashley Valley is well popu­lated. The rich valley soil supports many successful ranches. Ver­nal, whose population in 1920 was 1,309, is the commercial center of the valley and the principal town in the eastern part of the Uinta Basin.

The area is reached by highway, the nearest railroad points being Price, Utah, on the Denver & Rio Grande Western Railroad, about. 125 miles by road southwest of Vernal, and Craig, Colo., the terminus of the Denver & Salt Lake Railroad, 137 miles east of Vernal. Salt Lake City is 186 miles west by highway. Roads to all these places are normally good and are being improved in response to the de­mands of increasing automobile traffic.

Asphalt Ridge is accessible from Vernal by road at several places, but the only good roads that reach it are the Duchesne (Victory) Highway west of Vernal, which crosses the ridge in the northwestern part of T. 5 S., R. 21 E., and the road to Dragon, which crosses it in the northern part of T. 6 S., R. 22 E. A road has been constructed to the " asphalt" quarry (location 2, fig. 3), and in 1926 an automo­bile could reach the base of the hill beneath the quarry. Other poor roads and trails lead from ranches to " asphalt " and coal prospects.

G E O L O G Y

STRATIGBAPHY

Formations exposed.—The geologic formations of Ashley Valley are listed below.

Formations exposed, in Ashley Valley and Asphalt Ridge

System

Tertiary.

Cretaceous.

Series

Eocene.

Upper Cretaceous.

Formation

Uinta formation.

Mesaverde forma­tion.

Mancos shale.

Character

Varicolored shale, sandstone, and con­glomerate; bi tuminous sand in basal part.

Sandstone, shale, and coal.

Sandstone and shale.

Gray marine shale and sandstone.

Thick­ness (feet)

500+

l.OOOdb

5,000+

Bituminous s tion, which in i The uppermost the Williams I to buff sandstor the formation : verde, which co to the lies forn rocks of the U sandstone and tinguishable fr the base of the Mesaverde, and difficult to disc*

Uinta format titled by the w Basin, where th part of the basi River formatioi which are pecul duplicated in t. reds of the Uir the cream colors tic of the Wasa mapped by Gale and Green Rive:

Most and per locality is in th< where in this r Uinta formation Asphalt Ridge.

The Uinta foi as the Wasatch. missing and pro ceous rocks. At lar unconformity cuts downward (see fig. 3) app: eroded away be tween the forms siderable magmi

PART II

[See pi. 7, B.) lopes off rather •e are deep and

y is well popu-ranches. Ver-

Lercial center of rt of the Uinta

ad points being Railroad, about. lo., the terminus >f Vernal. Salt all these places

>onse to the de-

tt several places, hesne (Victory) ,he northwestern which crosses it been constructed 1926 an automo-•ry. Other poor d coal prospects.

BITUMINOUS SANDSTONE NEAR VERNAL, UTAH 81

f Ashley Valley

lit Ridge

r

stone, and con-sand in basal

U.

mdstone.

Thick­ness (feet)

500+

1,000±

5,000+ •

Bituminous sandstone occurs in the basal part of the Uinta forma­tion, which in this region is underlain by the Mesaverde formation. The uppermost Mesaverde rocks (which apparently correspond to the Williams Fork formation of northwestern Colorado) are gray to buff sandstones, for the most part medium grained and typical of the formation in the general region. The lower part of the Mesa­verde, which consists of sandstone and shale, apparently corresponds to the lies formation of northwestern Colorado. The characteristic rocks of the Uinta formation are red and cream-colored shale and sandstone and coarse siliceous conglomerate. These are easily dis­tinguishable from the Mesaverde rocks, but the sandstone beds at the base of the Uinta formation are in places much like those in the Mesaverde, and the contact between the formations is at many places difficult to discern.

Uinta formation.—The Uinta formation of this area has been iden­tified by the writer by tracing from the central part of the Uinta Basin, where the typical formation is exposed, and from the western part of the basin, where it definitely overlies the Bridger and Green River formations. Moreover, it shows colors and a lithologic habit which are peculiar to the Uinta formation and which are not exactly duplicated in the Wasatch formation in this general region. The reds of the Uinta formation possess a distinctive orange tint, and the cream colors an indescribable cast, neither of which is characteris­tic of the Wasatch formation. These rocks in Asphalt Ridge were mapped by Gale as a part of the Wasatch formation, but the Wasatch and Green River formations are absent from this locality.

Most and perhaps all of the bituminous sandstone of the Vernal locality is in the Uinta formation. The detailed sections given else­where in this paper show the character of the lower part of the Uinta formation. About 500 feet of the formation is exposed in Asphalt Ridge.

The Uinta formation lies unconformably on the Mesaverde rocks, as the Wasatch, Green River, and Bridger formations are entirely missing and probably also a considerable thickness of Upper Creta­ceous rocks. At one place at least the contact appears to show angu­lar unconformity. As noted by Gale, westward the base of the Uinta cuts downward into the Mesaverde sandstones, and at location 1 (see fig. 3) apparently the whole of the upper Mesaverde had been eroded away before deposition of the Uinta beds. The contact be­tween the formations therefore represents an unconformity of con­siderable magnitude,

82 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 19 3 0, PAST II

STRUCTURE

In Asphalt Kidge the strata dip south and southwest at angles ranging from 8° to 30°, and the strike ranges between N. 80° E. and N. 10° W. (See fig. 3.) In the central part of the ridge the strike is generally about N. 40° W., but toward both ends it swings west­ward, and at the northwest end, near location 1, it curves around to N. 80° E. These trends are broadly reflected in the contacts shown in Figure 3. The rocks here form part of the south flank of the Split Mountain anticline and dip toward the main structural depression of the Uinta Basin. At most places near the contact between the Mesaverde and Uinta formations the rocks appear to dip at about the same angle and in the same direction, but at location 8 the Uinta beds appear to diverge in strike from the underlying Mesaverde in a manner suggestive of angular discordance between the formations. The strike of the Cretaceous beds at this place is about N. 70° W., but that of the Uinta beds is apparently more nearly west, perhaps due west. The Cretaceous beds dip more steeply than the Uinta, suggesting that two stages of tilting occurred, one in pre-Uinta time and one in post-Uinta time.

B I T U M I N O U S S A N D S T O N E

GENERAL CHARACTER

The bituminous rock is sand or sandstone, gray in normal color, ordinarily medium grained but at many places fine grained, impreg­nated to various degrees with brownish-black bitumen. Much or perhaps all of the rock is simply sand held together by the bitumen, but as most of it is firm and rocklike in character it should be called sandstone. Some of the rock is barely stained brown by the bitumen, but in the richest rock the bitumen occupies more than the normal pore space of the sand. When fresh the rich rock is sticky and tough and yields to hammer blows much as chewing gum would. At a few outcrops the richest rock, heated by the sun, has flowed downhill in pillowy masses resembling lava of the pahoehoe type. The bituminous sandstone weathers to a characteristic blue-gray color. Samples that have been considerably weathered are dark brown in the interior, those that are less weathered are black. The lean and deeply weathered rock breaks like ordinary sandstone, but the fresh rich rock, as exposed in quarries and drift, is gummy and tough.

There are two kinds of bituminous rock. One is pure bituminous sandstone, as described above, and the other is conglomeratic, the pebbles of the conglomerate consisting of cream-colored to white pellets and irregular fragments of silt or very fine grained sand which are not impregnated with bitumen. Seams of this silt run

PART II

west at angles N.80° E. and idge the strike t swings west-rves around to :ontacts shown 11k of the Split iral depression 3t between the ) dip at about on 8 the Uinta Mesaverde in a he formations. )ut N. 70° W., west, perhaps

lan the Uinta, pre-Uinta time

TJ. S. GEOLOGICAL SURVEY BULLETIN 822 PLATE 7

i normal color, •ained, impreg-nen. Much or >y the bitumen, hould be called by the bitumen, lan the normal icky and tough

would. At a lowed downhill oe type. The due-gray color. rk brown in the The lean and

}, but the fresh y and tough. ure bituminous glomeratic, the lored to white 3 grained sand )f this silt run

A. ASPHALT RIDGE, UTAH, AS SEEN FROM THE NORTHWEST

tffassss*?** *r*&* &??*•#&*& m

J^S*9*+^3il^• fr*'80^-» . 4-. w .. v

B. FRONT OF ASPHALT RIDGE NEAR SOUTH END

U. S. GEOLOGICAL SURVEY BULLETIN 822 PLATE 8

<

J

P n

g

S P E C I M E N S O F B I T U M I N O U S S I L T - P E L L E T C O N G L O M E R A T E . SHOWING SHAPE, D I S T R I B U T I O N , A N D LACK O F S A T U R A T I O N O F P E L L E T S

A, Surface at right angle to bedding, showing flat fragments. B, Surface parallel to bedding, showing large rounded pellet and diversely oriented smaller ones. C, Surface parallel to bedding, showing raDge in angularity and orientation of pellets. All four-fifths natural size.

> « P cc

< O

C3 O • 3

O H O

p a ~

U. S. GEOLOGICAL SURVEY BULLETIN 822 PLATE 9

FACE OF QUARRY AT LOCATION 2 , ASPHALT R I D G E , U T A H

The black, freshly broken rock is visible on the right, and the dark-gray weathered rock elsewhere in the view. White silt pellets and seainlets are visible on several rock faces.

BITUMINOUS SANDSTONE NEAR VERNAL, UTAH 83

through some of the bituminous beds, usually along bedding planes. Samples of the conglomeratic rock are shown in Plate 8.

Samples of the rock were taken for analysis and laboratory study, and the results of these examinations are given on pages 88-95, in connection with conclusions tha t directly follow concerning the amount, availability, and uses of the material.

LOCALITIES AND DETAILED SECTIONS

The locations given on Figure 3 were made as closely as possible by taking compass bearings to physical features recognizable on Gale's map, but they are at best only approximate. The map was prepared by tracing essential features from Gale's map and adding such data as were obtained in the present examination.

Northwest of location 1 the rocks are completely covered, in the rounded hills forming the continuation of Asphalt Ridge as well as in the valley. Near location 1 the bitumen-bearing strata are cut off by a fault, shown on the map, but from the fault southwestward the rocks are fairly well exposed on the steep northeast slope of the ridge.

Location 1 is in the NW. ^ s e c - 3 0 ) T. 4 S., R. 21 E., where the following section is exposed:

Section o/ rocks at location 1 Feet

1. Conglomerate, gray, siliceous; pebbles, poorly sorted, 6 inches or less in diameter, principally of quartzite_ 40+

2. Bituminous sandstone, fairly rich 25 3. Concealed (probably bituminous sandstone) 10 4. Bituminous sandstone, like bed 6 22 5. Bituminous sandstone, containing many white pellets

(see p. 91) and seams 10 6. Bituminous sandstone, fine grained, moderately im­

pregnated at base, increasing upward in coarseness and content of bitumen; drift on this bed exposes many seamlets of pure bitumen and some seams of white clay . 56

7. Sandstone, very fine grained, white, thin bedded to massive; strike N. 80° E., dip 13° S 50-100

Total section 213-263 Total bituminous sandstone 113-123

In this section No. 6 is unquestionably the richest bed, but Nos. 2 to 5 might be profitably worked in a large-scale operation. (See p. 94.) No. 7 of the section is doubtless Cretaceous. The over­lying bituminous beds may also be Cretaceous, as, apar t from the content of bitumen and the silt pellets, they are lithologically similar to bed 7. The conglomerate may represent the base of the Uinta

84 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 19 3 0 , PART II BITUM

formation, but this is by no means certain, because at other localities a conglomerate bed which may be an extension of this bed lies some distance above the undoubted base of the Uin ta beds.

At location 1 several openings have been made in the principal bituminous bed, one of which is a drift about 150 feet long, and from these workings a moderate amount of bituminous rock has been taken away, apparently several years ago. The place was formerly accessible by a road, which has been largely washed out in the steep slopes near the workings but which in 1926 could be traveled by automobile as far as the base of the hill.

Location 2 is at a quarry in the N E . *4 s e c - %h T. 4 S., R. 21 E., where a large amount of bituminous rock has recently been taken out for use in paving the streets of Vernal. (See pi. 9.)

Between locations 1 and 2 the bituminous sandstone seems to be fairly uniform, and, as the following section shows, at location 2 it is nearly the same as at location 1.

Section of rocks at location 2 Feet

1. Bed and cream-colored sandstone and siliceous conglo­merate of the Uinta formation; thickness present in knobs near quarry 50

Apparent unconformity. 2. Bituminous sandstone, similar to bed 3 but in places

less impregnated 70 3. Bituminous sandstone, very rich, medium grained, con­

taining many seams of fine silt and pebbles or pellets of same material (difficult to measure on account of spread of outcrop, cross-bedding, and dip), about 120

4. Sandstone, fine grained, gray to cream-colored, containing fine-grained layers; at quarry strikes N. 75° W. and dips 11° S 30+

5. Sandstone, medium to coarse, gray, ferruginous in places; at base of hill strikes due east and dips 20° S.

Total section 270+ Total bituminous sandstone . 190

At this locality also it is difficult to determine whether the bitu­minous rock is Cretaceous or Tert iary. At the quarry the rock seems to be pa r t of the Cretaceous succession, as it rests conformably on beds of undoubted Cretaceous age and has the same general char­acter. The unconformity above bed 2 is suggestive, but it might be merely a local unconformity of the type common in continental beds like those that make up the Uinta formation. Fa r the r up the gulch from the quarry, however, the red beds of the Uinta come down into the bituminous series and appear to be interbedded with it.

The next easily accessible place southeast of location 2 is the point where the Duchesne Highway crosses Asphal t Ridge, and there small

amounts of bitun no satisfactory se(

Location 3 is e; T. 4 S., R. 21 E., i Uinta formation bituminous mate: conglomerate. Tl

1. Red and ci Uinta for

2. Conglomera 3. Shale, red a 4. Bituminous

weathers moderate]

Total Total

Dip of be<

The section at ] bituminous sandst not exposed, but ii location 2. South somewhat irregula the lower bed at k general zone.

Location 4 is in par t of Asphalt R section measured ]

1. Conglomera) 2. Conglomeral 3. Sandstone, j 4. Conglomeral 5. Shale, drab_ 6. Bituminous 7. Concealed— 8. Sandstone; 9. Bituminous

10. Shale and s 12. Shale, red :

sandstone 13. Bituminous 14. Sandstone, 1

15. Bituminous Base concea

Total i

PART II

other localities 3 bed lies some

the principal long, and from rock has been i was formerly ut in the steep 3e traveled by

4 S., R. 21 E., tly been taken

) le seems to be it location 2 it

Feet lglo-t in

aces

con-ts of read

ning and

ces;

50

70

120

30+

270+ 190

ether the bitu-the rock seems

onformably on i general char-, but it might in continental

Farther up the le Uinta come bedded with it. l 2 is the point md there small

BITUMINOUS SANDSTONE NEAR VERNAL, UTAH 85

amounts of bituminous sandstone are exposed in the road cut, but no satisfactory section is available.

Location 3 is east of the Duchesne Road in the SW. ^ sec. 33, T. 4 S., R. 21 E., at a gravel pit from which the conglomerate in the Uinta formation has been excavated for use as road metal. Some bituminous material has been quarried from beds below this conglomerate. The section follows:

Section at location 3 Feet

1. Red and cream-colored sandstone and shale of the Uinta formation; est imated 500±

2. Conglomerate, gray, siliceous, as at location 1 10-15 3. Shale, red and buff, sandy, mainly brick-red 33-35 4. Bituminous sandstone, fine grained, cross-bedded;

weathers blue-gray; brown-black when fresh; moderately impregnated (base not exposed) 3 0 +

Total section 573-580± Total exposed bi tuminous sandstone 3 0 +

Dip of beds 8° S.; s t r ike approximately N. 70° W.

The section at location 3 does not show the full thickness of the bituminous sandstone, and the rocks beneath the section given are not exposed, but it seems likely that the bed is much thinner than at location 2. Southeast of location 3 the bituminous beds appear to be somewhat irregular, and the bed at location 3 may not be the same as the lower bed at location 4, although it is unquestionably in the same general zone.

Location 4 is in the SW. 14 sec. 14, T. 5 S., R. 21 E., the steepest part of Asphalt Ridge. The rocks are unusually well exposed. The section measured here follows:

Section at location 4 Feet

1. Conglomerate, as of other sections, overlain by red shale. 2. Conglomeratic (silt-pellet) bituminous sandstone 5 3. Sandstone, gray 8 4. Conglomeratic bituminous sandstone 4 5. Shale, drab 5 6. Bituminous sandstone, i r regular ly impregnated 3 7. Concealed 3 0 ± 8. Sandstone; weathers brown . 8 9. Bituminous sandstone 5

10. Shale and sandstone, gray, locally bituminous Q± 12. Shale, red and yellow-green, interbedded with gray-buff

sandstone 3 0 ± 13. Bituminous sandstone— ; 16 14. Sandstone, white, thin bedded : 5 15. Bituminous sandstone 4

Base concealed. Total section 134± Total bituminous sandstone— 37

86 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 193 0, PART II

Beds 9, 10, and 11 of this section merge northwestward to form a single bed of bituminous sandstone about 15 feet thick, and still farther northwest this bed thickens to as much as 60 feet. About a mile northwest of location 4 the lower bed (13 to 15 of this section) begins to pinch out.

The beds in the foregoing section appear to be about 200 feet above the base of the Uinta formation, and their relation to the beds at locations 1 to 3 is uncertain.

Location 5, in the next gulch southeast of location 4, is also in the SW. % sec. 14, T. 5 S., R. 21 E. • Much more bituminous sandstone. is exposed in this locality, and the rocks in the Uinta formation show a much greater variability. The thicknesses given in the following section were estimated and thus afford merely a rough measure of the amount of bituminous material present, but they are probably accurate enough for the present purpose.

Section at location 5

1. Conglomerate (same as in the preceding sections). Feet 2. Bituminous zone (mainly bituminous sandstone) 30-50 3. Shale and sandstone (typical Uinta lithology) 150-180 4. Bituminous sandstone 3 5. Concealed interval 15 6. Bituminous sandstone 5 7. Shale 10 8. Bituminous sandstone 15 9. Interval 50

10. Bituminous sandstone (base not exposed) 2.0-25

Total section 298-353 Approximate total bituminous sandstone 100

Strike N. 40° W.; dip 17° SE.

In the next gulch southeast of location 5 there is exposed a similar fairly rich zone which continues for some distance southeastward but thins considerably before reaching location 6, in the NW. % sec- 25, T. 5 S., R. 21 E., as may be seen in the following section.

Section at location 6

1. Shale, etc., of the Uinta formation. Feet 2. Sandstone, gray, very slightly saturated with bitumen 15 3. Sandstone, gray, slightly saturated 3 4. Conglomerate of bituminous sandstone, moderately satu­

rated 1% 5. Sandstone, gray, slightly saturated (upper Mesaverde).

i9y2

About 500 feet southeast of location 6, across the gulch, considerably more bitumen is present, as may be seen in the following section:

1. Conglon 2. Conceal 3. Bitumin

ently

T T.

Location 6 is a gap that mar Between locati Mesaverde san« rough area of c form a low rid Asphalt Ridge head of a large verde ridge in I formation appe; the bitumen zoi

Location 7 is gulches, in the I ured there folio

1. Cream-col 2. Bituminoi

ately im 3. Sandstone 4. Bituminou 5. Covered (i 6. Bituminou 7. Coal, fair

Tots Tota

Strike N

About 100 yarc conglomerate of limestone. The ] doubtless derived are very irregulai thicken somewhat the main bitumint base. It is very i sandstone on the s

Location 8 is in mile west of the p

PART II

;vard to form a ;hick, and still feet. About a

of this section)

about 200 feet relation to the

4, is also in the nous sandstone formation show i the following igh measure of y are probably

Feet ___ 30-50 ___ 150-180

3 15

5 10 15 50

___ 20-25

___ 298-353 100

:posed a similar itheastward but NW. % sec. 25, on.

Feet en 15

3 satu-

1% le) . —

19%

ch, considerably [lowing section:

BITUMINOUS SANDSTONE NEAR VERNAL, UTAH

Section 500 feet southeast of location 6

87

1. Conglomerate like tha t in the section above. Feet 2. Concealed interval (probably shale) 60-70 3. Bituminous sandstone, evenly impregnated but appar­

ently not very rich (base not exposed) 50-55+

Total section 110-125 Total bituminous sandstone 50 -55+

Location 6 is near a wagon road that leads southwestward through a gap that marks the south end of the main part of Asphalt Ridge. Between locations 6 and 7 the topography changes. The beds of Mesaverde sandstone, which northwest of location 6 make a low rough area of discontinuous hogbacks at the base of Asphalt Ridge, form a low ridge that continues past the end of the main part of Asphalt Ridge and might be considered a minor branch of it. The head of a large gulch extends into the southwest side of this Mesa­verde ridge in rough, steep-walled canyons. The base of the Uinta formation appears in the upper parts of these canyons, and with it the bitumen zone.

Location 7 is at a narrow place in the bottom of one of these gulches, in the NW. y± sec. 31, T. 5 S., R. 22 E. The section meas­ured there follows:

Section at location 7 1. Cream-colored and red shale, limestone, and sandstone. F e e t

2. Bituminous sandstone, thin bedded, variable, moder­ately impregnated at base 3-8

3 . Sandstone, gray, thin bedded 9± 4. Bituminous sandstone, rich 1 5. Covered (oil-soaked shaly sandstone) 6 6. Bituminous sandstone <main bed) 6-7 7. Coal, fair to poor 2

Total section 27-33± Total bituminous sandstone 10-16

Str ike N. 85° W. ; dip 69° S.

About 100 yards farther west the bituminous zone is overlain by a conglomerate of limestone and quartzite pebbles whose matrix is limestone. The pebbles of Paleozoic limestone and quartzite were doubtless derived from the Uinta Mountains. The bituminous beds are very irregular for a mile or so in either direction and appear to thicken somewhat westward and then to thin again. At location 7 the main bituminous bed seems to be unconformable at both top and base. It is very irregular, and it pinches out against the Cretaceous sandstone on the south side of a big butte in sec. 31, T. 5 S., R. 22 E.

Location 8 is in the NE. *4 sec. 4, T. 6 S., R. 22 E„ about half a mile west of the place where the road to Dragon crosses the base of

88 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1930, PART II

the Uinta formation. Here the bituminous sandstone appears to be at the base of the Uin ta formation, although it might belong in the Cretaceous.

Section at location 8

1. Red, drab, and cream-colored shale. F e e t

2. Limestone, gray, hard; forms top of low ridge 3± 3. Shale, cream-colored, calcareous 25± 4. Sandstone, gray, partly impregnated with bitumen 5 • 5. Sandstone, gray, with lenses stained yellow-green 3 6. Bituminous sandstone 18 7. Sandstone, gray (upper Mesaverde) 50

Total section 104± Total bituminous sandstone : 23

Strike of Cretaceous rocks N. 70° W.; dip 18° S. Strike of bituminous bed nearly west.

Jus t east of location 8 the bituminous sandstone pinches out be­tween the shale of the overlying Uinta formation and the sandstone of the underlying Cretaceous formation. On the road to Dragon no bitumen is visible in either Cretaceous or Tert iary rocks.

COLLECTION AND EXAMINATION OF SAMPLES

Samples of the bituminous sandstone were taken near locations 1 and 2 for laboratory study. One sample of the richly impreg­nated rock from location 2 was submitted to the chemical laboratory of the United States Geological Survey for general chemical analysis, and all the samples were studied by the writer in the sedimentation laboratory at Ohio State University. The samples were analyzed to show the character of the principal kinds of rock.

In the Ohio laboratory a weighed sample was immersed in suc­cessive baths of carbon disulphide until the bitumen was extracted. The sand grains apparently were cemented by the bitumen alone, as treatment with the solvent sufficed to free all particles except a few that were cemented by a mineral cement. The remaining sand was dried, weighed, and analyzed mechanically by sieving. Standard sieves were used and the samples were shaken by machine for periods of 10 to 15 minutes. The specific gravity of the sand was determined by the pycnometer method and the rock density 2 of the bituminous rock by weighing a coated sample in water and in air. F rom these determinations the pore space was calculated, and porosity deter­minations were made by a modification of the method described by Russell.3 Aggregates of the sand, as well as the separate fractions

2 Rock density differs from specific gravity in that rock density takes into consideration the specific gravity of both the pore space and the constituent mineral grains.

3 Russell, W. L., A quick method for determining porosity : Am. Assoc. Petroleum Geolo­gists Bull., vol. 10, pp. 931-938, 1926.

BIT

resulting from scope. The sj tained by weig determining w alcohol and wa

In order to pellets in the c< of several kind and found ther

MECHANICS

The mechani. F igure 4. San surfaces in the pregnated, soft, location 1 and r from the q u a r r near location 1.

The sand in sample 1 is fine same general pr mum fraction h remainder is in the characterise action of waves rents. The shai a noteworthy ch in the finer grac less than 12 per either by waves form intensity. any finer materi an ideal case th sideration is base has not yet been : thus far studied of lakes and the this characteristi limits on the cot worked material doubtless represe by saltation or r< is much less abun

4 Udden, Johan, Mec vol. 25, p. 658, 1914.

PART II BITUMINOUS SANDSTONE NEAR VEENAL, UTAH 89

appears to be belong in the

Feet ._ 3± ._ 2 5 ± ._ 5-._ 3 ._ 18 ._ 50

.___ 104±

._— 23 S.

inches out be-the sandstone ad to Dragon rocks.

LES

near locations •ichly impreg-cal laboratory tnical analysis, sedimentation were analyzed

nersed in suc-was extracted. lmen alone, as 3 except a few ning sand was riff. Standard ine for periods ras determined ,he bituminous \ From these xorosity deter-1 described by irate fractions

into consideration grains. j. Petroleum Geolo-

resulting from mechanical analysis, were examined under the micro­scope. The specific gravity of the extracted bitumen was ascer­tained by weighing a sample in absolute alcohol and in air, and by determining with a Westphal balance the density of a solution of alcohol and water in which the bitumen neither sank nor floated.

In order to determine qualitatively the permeability of the silt pellets in the conglomeratic bituminous rock, the writer placed drops of several kinds of crude petroleum on the pellets of several samples and found them highly absorbent.

MECHANICAL A N A L Y S I S A N D MICROSCOPIC E X A M I N A T I O N

The mechanical constitution of the sands is shown graphically in Figure 4. Samples 1, 2, and 3 were taken from freshly exposed surfaces in the quarry at location 2 and represent the richly im­pregnated, soft, gummy rock. Sample 4 was taken from the drift at location 1 and represents finer-grained, harder rock than the average from the quarry. Sample 5 was taken from the weathered outcrop near location 1, to represent the " conglomeratic " type.

The sand in samples 1, 2, and 3 is fairly well sorted. Tha t in sample 1 is finer than the other two, but all three samples show the same general proportions of the constituent grade sizes. The maxi­mum fraction in all three approaches 70 per cent, and most of the remainder is in the size next coarser than the maximum. These are the characteristics of well-sorted sand, such as is deposited by the action of waves or the long-continued flow of slightly varying cur­rents. The sharp drop from the maximum to the next finer grade is a noteworthy characteristic of these sands. In sample 1 the amount in the finer grades is almost negligible, and in samples 2 and 3 it is less than 12 per cent. This condition is most likely to be produced either by waves of fairly constant size or by currents of nearly uni­form intensity. Such waves or currents will continually carry away any finer material and wash, rework, and deposit the coarser. In an ideal case the lower limit should be sharply fixed. This con­sideration is based mainly on theory, which so far as the writer knows has not yet been fully tested but which is borne out by many examples thus far studied by the writer, notably the deposits on the beaches of lakes and the open sea. Shore deposits of large rivers also show this characteristic, although less clearly, as might be expected. The limits on the coarser side are likewise those characteristic of well-worked material. The amounts in the coarser proximate g r a d e 4

doubtless represent material which the waves or currents could move by saltation or rolling but could not carry suspended; this material is much less abundant than the suspended material.

* Udden, Johan, Mechanical composition of clastic sediments : Geol. Soc. America Bull., vol. 25, p.' 658, 1914.

90 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1930, PABT II BI1

Sample 4 is not so well sorted as the first three, but it shows in part the characteristics of well-worked material. The sand is mainly fine, and the maximum grade contains about 60 per cent of the total. The conditions that produced this sand were probably less constant

100

90 8 0

j - 7 0 ,

°50 |

£*° 0. 30

20

10

I.Rich sand f r om quarr y a

location 2

0J6

:

258

H

6 M

1 ll 4.6 £9

32 16 8 4 2 I VZ % % Jfe SIZE OF PARTICLES (mm)

100

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H 70 z U 60 O

50 or u 40

•30

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3.Rich sand f r om quarr at location 2

03

y

195 •

68.

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100

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°-30i 20 10

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pellet conglor ner ate near location 1

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32 16 8 4 2 I £ yA\ Jjg S I Z E OF PARTICLES (mm.)

100

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2. Rich sand f r o m quarry a t location 2 '

677

32 16 8 SIZE OF PARTICLES ( m m }

100

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Moderately rich i d f rom lo cat

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32 16 8 4 2 I '/2 \ jfe Jfe"' S I Z E OF PARTICLES (mm.)

100

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5. Sand matr ix only, silt pellets excluded

38. 5 ^ 3 3 . 2

170

"*

jeaaa tfi 32 16 8 4 2 I Jfe & Jfe Jfe SIZE OF PARTICLES (mm.)

F I G U R E 4..—Graphic r e p r e s e n t a t i o n of m e c h a n i c a l a n a l y s e s of s a n d r e s i d u e from b i t u m i n o u s s a n d s t o n e o f A s p h a l t Ridge , U t a h

than those for samples 1, 2, and 3. There is a considerable admix­ture of material finer than the maximum—nearly 25 per cent—which probably indicates considerable slackening of the water currents

with net pred represents a rr samples 1, 2, {

The rock re Offhand, it ap the sandy mat are not. Thee clearly against pi. 8.) Micro veals the fact quartz, of the be referred to :

The bitumen the other samp necessary to fi tegrated immei a few hours. weathered cond the subsequent was taken to p: but doubtless n tions in the sizt accurate. Furt did not contain mum size of 50 the writer. In

Two graphs { the aggregate a the silt pellets 3 the sand matrix pretation of th aggregate, has i matrix of sand i of the stream. sorted material drop from the n gentler fall of tl irregular condit currents commo most abundantly separation of th* descent of the ci which this sand > the sand of the silt pellets may h

BITUMINOUS SANDSTONE NEAR VERNAL, UTAH 91

with net predominance of silt ing over washing. This sample, then, represents a modification of the conditions tha t produced the sand of samples 1, 2, and 3.

The rock represented by sample 5 is in some respects a curiosity. Offhand, it appears to be a typical clay-pellet conglomerate in which the sandy matr ix is impregnated with bitumen but the clay pellets are not. These clay pebbles are cream-colored and stand out very clearly against the black background of the bituminous matr ix. (See pi. 8.) Microscopic examination of the clay pellets, however, re­veals the fact that they are not clay but chiefly very finely divided quartz, of the grade usually termed fine silt. They will therefore be referred to as silt pellets, and the rock as silt-pellet conglomerate.

The bitumen of sample 5 dissolved much more slowly than that of the other samples, digestion in carbon disulphide for two days being necessary to free the individual grains. Samples 1, 2, and 3 disin­tegrated immediately on soaking in the solvent, and sample 4 after a few hours. The slow solution of sample 5 may be due to the weathered condition of the sample. In the process of soaking and in the subsequent mechanical handl ing of the material every precaution was taken to preserve the original size and shape of the silt pellets, but doubtless many were chipped and fractured, so that the propor­tions in the sizes larger than 1 millimeter shown in F igure 4 are not accurate. Fur thermore, the sample selected for mechanical analysis did not contain the largest observed silt pellets, which reach a maxi­mum size of 50 by 2Q by 5 millimeters in other samples collected by the writer. In the deposits still larger sizes may perhaps be found.

Two graphs are given in F igure 4 for sample 5, one representing the aggregate and the other the sand matr ix . This is done because the silt pellets may in a certain sense be considered accidental and the sand matr ix the more significant par t of the rock for the inter­pretation of the analysis. The first graphic figure, showing the aggregate, has the general aspect of a river gravel consisting of a matr ix of sand with pebbles worked in at times of increased activity of the stream. The sand itself shows the characteristics of poorly sorted material rather typical of stream deposits. There is a sharp drop from the maximum ingredient to the next coarser grade, but a gentler fall of the pyramid on the fine side. This suggests the more irregular conditions characteristic of stream deposition, in which currents comm6nly vary so greatly tha t the size being deposited most abundantly differs considerably from time to time. The sharp separation of the silt from the silt pellets, emphasized by the abrupt descent of the curve on the coarse side, shows tha t the water from which this sand was deposited was more active than that from which the sand of the other samples was deposited and suggests tha t the silt pellets may have been brought in by some unusual process.

92 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1 9 3 0, PART II

The grains of the sand are mainly clear quartz and dark-gray quartzite, with minor quantities of cream-colored chert, rose quartz, amethyst, and chalcedony. The sand of all the samples is similar. The coarser fractions of all samples contain fragments of sandstone and of the cream-colored siltstone of the silt pellets. The sandstone fragments are firmly cemented by a small quanti ty of secondary silica. In the medium and coarser fractions (larger than 0.25 milli­meter) the dark-gray quartzite is present in sufficient quantity to give these sands a dark color; in the finer fractions it is sparingly present, and these 'fractions are white to cream-colored. A notable feature of the material is the very small quantity of clay; the finest fractions contain almost exclusively angular grains of clear quartz, with a sprinkling of heavy.minerals among which pyrite, magnetite, and muscovite are most abundant. Sample 4 contains a large amount of pyrite.

Most of the individual grains are angular. A count of several microscopic fields of the aggregate of sample 2, covering about 200 grains, showed about 2 per cent well rounded (no flat faces), 1 per cent moderately rounded (flat faces visible), 5 per cent subangular (corners and edges rounded), and 92 per cent angular. Estimates of all other samples gave similar results except for the sandstone frag­ments of the "conglomera te" (sample 5) , which are mentioned below.

The silt pellets of the " conglomerate " show some curious charac­ters. Nearly all are flat and chiplike, and many are angular. All have been indented by the grains of the surrounding sand, and the individual pellets, when freed in the mechanical analysis, are so in-crusted by inset sand grains that they look like fragments of sand­stone. Doubtless the flattened shape of many of the pellets is due to pressure upon rounded balls of the soft material. The angular fragments, however, appear to have been chipped when fairly firm. Why the pellets should have cohered so well when soft is not easy to see; the apparent amount of clay is small, and the material is highly absorbent and under the microscope appears to be little more than an aggregate of very fine quartz grains.

The sand of the conglomerate differs somewhat from tha t of the other samples in tha t the fractions greater than 0.5 millimeter contain many fragments of sandstone in which the grains are on the whole better rounded than the free grains of the sand. Probably half of the grains in the sandstone fragments are at least moderately rounded, and many more are subangular. Very few of the free grains in the sand are rounded. The fractions finer than 0.5 milli­meter are similar in character to the sand of the other samples.

The predominance of angular grains does not appear to agree with the sorting of the sand: sand as well sorted as tha t in samples 1 to 3

BITT

would presume transportat ion however, withe It is obvious tl has been in san rence, in the co gray quartzite comparatively s are not as smal dance of quar t the sediments n those authors v of red quartzite in this materia] quartzite that The evidence af a complex sour well sorted sam ably came from marine sandstoi ably not far { involved rapid 1

Two specimei found to have has a rock den sample 2 Was fo The pore space cent, and tha t o other samples f: ification of the and 37.9. Som. space than this: the Geological ' usual pore spac cent. The samj: in which the wi bodies free from

The sample si ical Survey was soluble in carbo soluble in carbon

PART II

nd dark-gray b, rose quartz, les is similar. ; of sandstone The sandstone of secondary

mn 0.25 milli-tt quantity to t is sparingly d. A notable lay; the finest I clear quartz, ite, magnetite, i large amount

ant of several •ing about 200 t faces), 1 per flit subangular

Estimates of andstone frag-ire mentioned

•urious charac-angular. All sand, and the

^sis, are so in-nents of sand-; pellets is due

The angular en fairly firm. t is not easy to terial is highly ttle more than

am that of the limeter contain e on the whole obably half of ist moderately JW of the free than 0.5 milli-jr samples. ,r to agree with samples 1 to 3

BITUMINOUS SANDSTONE NEAR VERNAL, UTAH 93

would presumably have been considerably worn in the process of transportation and sorting. This evidence can not be evaluated, however, without consideration of the possible sources of the sand. It is obvious that part of the material, or perhaps nearly all of it, has been in sandstone before. However, the nearly exclusive occur­rence, in the coarser fractions, of the highly angular grains of dark-gray quartzite suggests that these grains may have come only a comparatively short distance from a fresh body of quartzite and so are not as small nor as much worn as the quartz grains. An abun­dance of quartzite is present in the Uinta Mountains, from which the sediments may have been derived, but most of it is reported, by those authors who have described it, as red or white. The absence of red quartzite in the sand suggests that the streams which brought in this material had not yet begun to erode the thick series of red quartzite that makes up the main core of the Uinta Mountains. The evidence afforded by the sands considered here seems to point to a complex source, including some fresh quartzite and some fairly well sorted sandstone and siltstone. The few rounded grains prob­ably came from older beds of sandstone, possibly one of the littoral marine sandstones of the Upper Cretaceous. The source was prob­ably not far away, and the process of accumulation probably involved rapid but efficient sorting.

EOCK D E N S I T Y A N D PORE SPACE

Two specimens of the the rock from location 2 (sample 2) were found to have a rock density of 2.03. One specimen of sample 4 has a rock density of 1.99. The specific gravity of the sand of sample 2 Was found to be 2.63, slightly less than that of pure quartz. The pore space of sample 2, determined from these data, is 38 per cent, and that of sample 3 is 33.7 per cent. The porosities of three other samples from the quarry at location 2, determined by a mod­ification of the method described by W. L. Russell, are 29.5, 37.0, and 37.9. Some of the material, however has much greater pore space than this; that of the sample examined in the laboratory of the Geological Survey was reported to be 47 to 49 per cent. The usual pore space of an aggregate of identical spheres is 47.64 per cent. The samples that show the greatest pore space are of a type in which the writer recognized in the field the presence of bitumen bodies free from sand grains.

BITUMINOUS CONTENT OF S A N D

The sample submitted to the chemical laboratory of the Geolog­ical Survey was found to contain 12.8 per cent by weight of bitumen soluble in carbon disulphide, and as practically all the bitumen is soluble in carbon disulphide, this represents nearly the total quantity.

94 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1 9 3 0, PART II B I T !

Sample 1 was found by the writer to contain 12.4 per cent of bitu­men ; sample 2, 14.0 per cent; sample 3, 12.0 per cent; sample 4, 8.3 to 9.0 per cent. Six other samples, selected at random from the material at location 2, were found to contain 13.3 to 15.1 per cent of bitumen. The average for the six samples is 14.2 per cent. The content of sample 5 was not determined because it constitutes so small a part of the bituminous strata, and because the percentage varies so greatly with the distribution of the silt pellets that even the average of several determinations might jdeld a misleading result. The percentages here given are used to determine the amount of bitumen present in the deposit in an estimate given on pages 95-97.

CHEMICAL N A T U B E OF T H E B I T U M E N

The sample submitted to the chemical laboratory of the Geological Survey was examined by E. Theodore Erickson, who reports as follows:

Chemical character of bituminous sand- from Asphalt Ridge, Utah

Per cent Loss (moisture) obtained at 105° C. for 1 hour 0.20 Residue obtained upon ignition 86.45 Total sulphur by the Carius method .09 Soluble in carbon disulphide 12.8 Fixed carbon in residue from evaporation of carbon di­

sulphide ; 7.1 Soluble in petroleum ether, specific gravity, 0.644 11 Amount of hydrocarbon mater ia l extracted by petroleum

ether of chemically saturated na ture 65

The bitumen occurring in the sample differs in the following respects from native aspha l t : (1) The proportion of solubility in light petroleum ether com­pared with the solubility in carbon disulphide is somewhat higher than tha t given by typical asphalt materials . The mater ia l designated asphaltenes, which is insoluble in l ight petroleum ether, may comprise more than one-third of the composition of nat ive asphalt . (2) The yield of fixed carbon is lower. Na tu ra l and artificial asphalt mater ia l s yield about 15 per cent of fixed carbon. (3) The sulphur content is unusually low. Native asphal ts contain from 1.7 to 10 per cent 5 of sulphur.

The bitumen appears to consist of residual mater ia l derived from a paraffin-base petroleum or a petroleum containing a high proportion of paraffin series and other sa turated hydrocarbons. This conclusion is supported by the high solubility of the bitumen in the sample in light petroleum ether, in which the above-mentioned types of hydrocarbon mater ia l a re soluble, and by the high proportion of saturat ion noted in the extracted bitumen.

Further examination of the bitumen by Mr. Erickson shows that it contains a small quantity of paraffin.

6 Holde, D., The examination of hydrocarbon oils and of saponiflable fats and waxes, p. 270, New York, 1922.

Thus it appe sand," and oth< to these deposi be abandoned h sandstone." Tl paraffin petrolei to the source ai into its origin a

The specific £ 0.980.

WEL

Several wells have penetrated Two of these we R. 21 E., and th 6, T. 5 S., E. 21 the bituminous wells contained to be pumped. been drilling a -of the SE. % se penetrated a sat 1,500 feet it was fluid bitumen so has a direct bear nous sandstone i

The data prese rough estimate o: able for mining i estimate, the wri nated in the foil occurrence and ] justify separatior

In the section and the Duchesn bed is 30 to 120 2 by (SO to 70 fee continuous with these beds extenc outcrop. The asu available rock see

76848°—31

PART II

cent of bitu-sample 4, 8.3

lorn from the .1 per cent of er cent. The constitutes so he percentage lets that even eading result. ie amount of >ages 95-97.

,he Geological 10 reports as

dge, Utah

Per cent 0.20

86.45 . 09

___ 12.8 di-

7.1 11

urn 65

g respects from eum ether comr-igher than that >haltenes, which one-third of the lower. Natural 2d carbon. (3) lin from 1.7 to

from a paraffin-E paraffin series ;ed by the high ;r, in which the nd by the high

)n shows that

BITUMINOUS SANDSTONE NEAR VERNAL, UTAH 95

fats and waxes,

Thus it appears that the designations " asphalt rock," " asphaltic sand," and others of similar nature which have long been applied to these deposits are not only inexact but misleading and should be abandoned in favor of a more general term such as "bi tuminous sandstone." The recognition of this material as the residue of a paraffin petroleum rather than a typical asphalt lends added interest to the source and suggests the desirability of further investigation into its origin and history.

The specific gravity of the bitumen, determined by the writer, is 0.980.

WELLS DRILLED TO T H E BITUMINOUS S A N D

Several wells drilled a short distance southwest of Asphalt Ridge have penetrated the bituminous sandstone beds at moderate depth. Two of these were drilled in 1911 and 1912; one is in sec. 6, T. 5 S.3

E. 21 E., and the other in sec. 35, T. 4 S., R. 20 E. The well in sec. 6, T. 5 S., R. 21 E., is only about a mile southwest of the outcrop of the bituminous sandstone beds. It is reported that each of these wells contained a small quant i ty of black oil tha t was too viscous to be pumped. Recently, the Western Venture Corporation has been drilling a well close to one of these old wells near the center of the SE . 1,4 sec. 6, T. 5 S., R. 21 E. At a depth of 1,270 feet it penetrated a saturated sandstone bed, and at depths of 1,300 and 1,500 feet it was making a small quanti ty of gas. The finding of fluid bitumen so close to the outcrop of the bituminous sandstone has a direct bearing on estimates of the reserves of minable bitumi­nous sandstone in Asphalt Ridge.

AMOUNT OF B I T U M E N

The data presented on the foregoing pages afford the basis for a rough estimate of the amount of bituminous rock present and avail­able for mining in Asphal t Ridge. For the purpose of making this estimate, the writer has divided the area into three tracts, desig­nated in the following paragraphs, in each of which conditions of occurrence and richness of the rock are sufficiently different to justify separation.

In the section of outcrop between the fault west of location 1 and the Duchesne road, about 2y2 miles, the principal bituminous bed is 30 to 120 feet thick and is overlain between locations 1 and 2 by gO to 70 feet of thinner beds which in places are practically continuous with the main bed. It seems safe to assume that all these beds extend under cover 1^ miles southwestward from the outcrop. The assumption of a greater distance beneath cover for available rock seems unwise, because of uncertainties in the mining

76848°—31- 7

•6/-.

96 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1 9 3 0 , PART II B I

and possibly also because of the more nearly fluid bitumen found in the wells drilled southwest of Asphalt Bidge. A simple calculation, using these linear dimensions and weighted averages for the thick­nesses of bituminous rock, shows the total amount present to be about 615,000,000 cubic yards.

The next section of outcrop, from the Duchesne road to a point midway between locations 5 and 6, about 5 miles long, contains thinner beds which are more widely spaced (see sections for locations 5 and 6, p. 86), so that the conditions of mining will be somewhat different from those in the tract above described. Here the main beds appear to have an average thickness of about 11 feet. On the assumption of an extent of iy2 miles from the outcrop, as before, the total amount of bituminous rock appears to be about 435,000,000 cubic yards, of which more than 345,000,000 cubic yards is in the main beds.

The next 1*4 miles of outcrop appears to contain no rock rich enough to consider commercially. Beyond this barren interval the succeeding section of outcrop, which is about 4 miles long, contains leaner rock than that in the two tracts already considered and, ow­ing to changes in topography, presents still different conditions for mining. In this stretch the main beds average 18 feet in thickness and the minor beds about 3 feet. The total amount of bituminous rock present, to a distance of iy2 miles from the outcrop, is proba­bly about 125,000,000 cubic yards. The factors for this estimate are considerably more variable than for the foregoing two, and the pos­sibility of error, in either direction, is accordingly greater. These estimates are probably all conservative.

To summarize the figures given above, it seems that the area s h o u Q I ^ minouB j r o c k ^ O n ^ of_. rack ..at, .Location 2 weighs about 1.68 tons, and the amounts named above may be trans-

"formed into tonnages By the_use of that f ac to j^ The Jx>tal amount IsHflius aTjourT OTO OOO gOO tons, and the amount in the first tract (probably the most promising^ of_all)_is_..about ljOSQjQOOjO^O tons. ""Translated into barrjels of petroleum residue and of original petroleum these amounts yield in te re j^g^gure^s r"~TKe^^^^^^ tween locations_l and 3 contains 9 to 15 per cent t$L .weightyof

bitumen, and_th^jrock^Jhe_fir^i: tract,above estimated tKuaijojQiains ^93,000,000 to 155,000,000 tons of the bitumen. One barrel of 42 gallons of the bitumen (specific gravity 0.980) weighs"333" pounds', and a t o n thus contains 5.831 barrels^ The bituminous rock esti­mated" for the first tract therefore Barrels" of bitumgn. If, as seems likely, the averag^jpj^ness of the rock m thefirst or northwestern tract is 13 per-cent, the amount

is 785,000,000 the total amc of bitumen^t of bitumen i the formatioi writer's opini

.1.1 • i . l . - -<W--W,W> .... l_ • i l l . !• ill. Ill I

and may be e1

was derived ents (gasolint the bitumen ] t™Ieum?~Th( mous. The t about 898,000 Mountain fiek With due all. striking. It i accumulation.

Undergroun most of the bi ing could reac mining is feaf reach. At H/2

would be abou to 500 feet for 20°, 2,900 feet. ations, because principally by flow in underg mining will ha

I t may be o: of the localiti where strippin carried on. U most places th< bed is quarried are where gulc have laid bare containing larj These conditio: been taken of 1 cently been qat Vernal.

I

PART II

men found in Le calculation, for the thick-present to be

ad to a point ong, contains 3 for locations be somewhat

[ere the main feet. On the op, as before, ut 435,000,000 ards is in the

no rock rich n interval the long, contains ered and, ow-conditions for it in thickness of bituminous ;rop, is proba-is estimate are >, and the pos-reater. These

that the area Yards o"f bitii? at location 2

jnay be trans -3 total amount "zi — t - - . .• mi- - -JJII*-„-:.--^JJ i"" • l1t * n ' ^ r

the first tract

id of original

„hjL jveight^of d.iJmaxojatains i barrel of 42 hs 343jpounds, IOUS rock esti-

gg^jdchness of igt, the amount

BITUMINOUS SANDSTONE NEAR VERNAL, UTAH 97

f>

is 785,000,000 barrels. For the whole area, on the assumption that 'the total amount oi rocS^aboye^estimated contains only 10 per cent of bitumenTtoldlow for the lean rock at the south end, the amount of bitumen is about 1.150,000.000 barrels. The tojaljbjtumen in fKe formation in the area probablx^^ceedsjhis amount. In the writers opinion^ i t J s nearer .J 5 i ixyW0i^ Jtarrels _than 1,000 00Q,(W0 and may be even greater. If the petroleum from which the bitumen was delrivedcontained originally over one-third volatile constitu­ents (gasoline, kerosene), as is likely, then it is fair„.to-assume-that the bitumen represents 1,50J),000300Q tp^^pp^OOpJIOp,^?!©!^.©^^-trHeuih.^ The original amount of petroleum must have been enor-mous. The total production of the United States for 1928 was about 898,000,000 barrels, and the total production of the Rocky Mountain fields from 1890 to 1928 has been only 354,000,000 barrels. With due allowances for loss in recovery, the comparison is still striking. It is clear that these^bituminous sands J5e irjesent_a«Jajcge, accumulation of petroleum—a lost oil field" of notable proportions.

M I N I N G

Underground mining of some sort will be necessary to recover most of the bitumen above estimated; quarrying and steam-shovel­ing could reach only a small fraction of the total. If underground mining is feasible, the whole amount ought to be at least within reach. At iy2 miles from the outcrop and at a dip of 10° the cover would be about 1,400 feet thick (plus or minus varying amounts up to 500 feet for irregularity of surface relief); at 15°, 2,100 feet; at 20°, 2,900 feet. Difficulties will probably be met in any mining oper­ations, because the rock, though compact, is apparently held together principally by the bitumen and will have a tendency to yield and flow in underground workings. Probably some special methods of mining will have to be devised.

It may be of value to point out the mining possibilities of some of the localities. The most favorable places are obviously those where stripping is easy and open-pit mining or quarrying can be carried on. Unfortunately, the dip of the rocks is so steep that in most places the amount of the overburden becomes excessive as the bed is quarried into the hill. The only places where this is not true are where gulches eroded nearly parallel to the strike of the ridge have laid bare large areas of bituminous rock and separated ridges containing large quantities of the rock overlain by a thin cover. These conditions exist at location 2, where advantage has already been taken of the ease of mining, and the bituminous rock has re­cently been quarried for use as road metal in paving the streets of Vernal.

98 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 19 3 0, PART II

At location T is a moderately large area which could be stripped, but it is in a very rough gulch and is difficultly accessible. At this place, on the south side of the ridge, the steep stream channels follow the dip of the rocks, thus producing a favorable situation for stripping. However, the quantity and quality of the rock avail­able are probably somewhat low for such operations.

Between location 6 and the southeast end of the outcrop most of the low ridge affords fairly good ground for stripping, but the rock is in most places doubtless too lean for profitable exploitation.

Moderate amounts of rock could be quarried at most places on the outcrop between locations 1 and 5, but probably not enough to justify the installation of much equipment.

Acknowledgments.. -Amsden formation ii

tana Ashley Valley, Utah

formations expost Asphalt Eidge, Utah

features of formations expost structure in views of

USES

The natural sandstone appears to make a good jpaving material. Pavemenll"T15M*ml9!^ material^ from Asphalt Ridge without the addition of any other^ingredients. werePm goooT"'' condition in 1936and promised to,,,rgjLy<L exc§llent service, ?

The bitumen itself might be profitably amenable to some of the recently developed processes of hydrogenation whereby the lighter hydrocarbons suitable for motor fuel have been synthesized from heavy bituminous residues.

Bearpaw shale in cen channels at con

sandstoni Big Horn County, M

correlation of geoJ those in (

drainage of geology and mine

map showing stratigraphy of, g water supplies in.

Bituminous conglom< specimen;

Bituminous sandstoj amount o

chemical charade collection and exa detailed sections < general character mechanical anal

examinati mining of rock density and uses of wells drilled to....

Bridger mine, Carboi Burgin mine, Carbon

Carbon County, Moi correlation of geol'

those in o drainage of geology and mine)

map showing. stratigraphy of, g< water supplies in.

Carlile and Niobrara ern Monti

Chug water formatioi Montana.

Chugwater sands on )

PART II

1 be stripped, ible. At this 3am channels ible situation tie rock avail-

,crop most of )ing, but the exploitation. places on the agh to justify

I N D E X

ing material. ; tha material^ p ingredients, ;ive_^excellent

some of the y the lighter hesized from

A Page

Acknowledgments 2 Amsden formation in-central southern Mon­

tana.- 11-12 Ashley Valley, Utah, features of 78-80

formations exposed in __ 80-81 Asphalt Ridge, Utah, face of quarry on pi. 9

features of 78-80 formations exposed in 80-81 structure in. - ._ 82 views of pi. 7

B

Bearpaw shale in central southern Montana. 46-47 channels at contact of, with Lennep

sandstone pi. 5 Big Horn County, Mont., coal in . . . 63-67

correlation of geologic formations in, with those in other areas pi. 2

drainage of 6-6 geology and mineral resources of parts of. 1-70

mapshowing pi. 1 (in pocket) stratigraphy of, general features 7-9 water supplies in _ 7

Bituminous conglomerate near Vernal, Utah, specimens of . pi. 8

Bituminous sandstone near Vernal, Utah, amount of bitumen in 93-94,95-97

chemical character of 94-95 collection and examination of samples of. 88-89 detailed sections of 83-88 general character of 82-83 mechanical analysis and microscopic

examination of __. 89-93 mining of 97-98 rock density and pore space of 93 uses of. 98 wells drilled to 95

Bridgermine, Carbon County, Mont 64 Burgin mine, Carbon County, Mont 64

C

Carbon County, Mont., coal in 63-67 correlation of geologic formations in, with

those in other areas pi. 2 drainage of 5-6 geology and mineral resources of parts of. 1-70

mapshowing pi. 1 (in pocket) stratigraphy of, general features 7-9 water supplies in 7

Carlile and Niobrara shales in central south­ern Montana 34

Chugwater formation in central southern Montana 14-17

Chugwater sands on Red Dome, Mont pi. 5

Page Claggett formation in central southern Mon­

tana.. . 38-42 outcrops of pi. 4

Cloverly formation in central southern Mon­tana 23-27

outcrop of basal conglomerate of pi. 3 Coal from Stillwater County, Mont., analysis

of 66 Colorado group in central southern Montana. 27-34 Cretaceous sandstone, marine, in Grand

County, Colo 72 Cretaceous shale in Grand County, Colo 72

D

Dakota sandstone in Grand County, Colo... 71-72

E

Eagle sandstone in central southern Montana. 36-38 coal in 63-65 outcrops oi pi. 4

Embar (?) limestone in central southern Montana.. 14

F

Faults in central southern Montana 51-54 Folds in central southern Montana 54-55 Frontier formation in central southern Mon­

tana 32-33

G

Gas in central southern Montana, search for. - 55-63 Granby anticline, Grand County, Colo.,

geologic map of pi. 6 stratigraphy of 71-74 structure of 74-75 suggestions for exploration for oil and gas

on 75-76 Greybull sandstone member of Cloverly for­

mation in central southern Mon­tana 26-27

Ground water in central southern Montana.- 67-70 Gypsum in central southern Montana 67

J

Judith River formation in central southern Montana - 42-46

clays and sandstones of pi. 4 coal in 65-67

K

Knappen, R. S., and Moulton, G. F., Geol­ogy and mineral resources of parts of Carbon, Big Horn, Yel­lowstone, and Stillwater Coun­ties, Mont 1-70

Knowlton, F. H., fossils identified by 42

99

100 INDEX

L Page

Lance formation in central southern Mon­tana— 49-50

Lennep sandstone in central southern Mon­tana — 48-49

channels in . pi. 5 Lowering, T. S., The Qranby anticline,

Grand County, Colo 71-76

M

Madison limestone in central southern Mon­tana.. . 11-12

box canyon in pi. 3 Middle Park formation, Grand County, Colo. 73 Miocene beds in Grand County, Colo 74 Montana, field work in central southern 2 Montana group in central southern Montana. 34-49 Morrison formation in central southern

Montana 20-23 Morrison (?) formation in Grand County,

Colo 71-72 Moulton, G. F., with Knappen, R. S., Geol­

ogy and mineral resources of parts of Carbon, Big Horn, Yel­lowstone, and Stillwater Counties, Mont_ 1-70

Mowry shale in central southern Montana.._ 30-32

N

Niobrara and Carlile shales in central south­ern Montana 34

O

Oil, search for, in central southern Montana.. 55-63 suggestions for exploration for, in Granby

anticline, Grand County, Colo.. 75-76

P

Parkman sandstone member of Claggett formation in central southern Montana, outcrops of.. pi. 4

sections of 40,41 Peay sandstone member of Frontier forma­

tion in central southern Montana.. 32,33 Petroleum. See Oil. Pliocene (?) gravel in central southern Mon­

tana 50 Pryor Mountains, central southern Montana,

surface features near 3-5 Public-land surveys in central southern Mon­

tana, accuracy of 6-7

Q

Quaternary alluvium in central southern Montana 50

R Page

Reeside, J. B., jr., fossils identified by..20,35,42,48-

Spieker, E. M., Bituminous sandstone near Vernal, Utah 77-98

Stillwater County, Mont., coal in 63-67 analysis of 66:

correlation of geologic formations in, with those in other areas pi. 2

drainage of 5-6 geology and mineral resources of parts of.. 1-70

map showing pi. 1 (in pocket) stratigraphy of, general features 7-9 water supplies in 7

Structure in central southern Montana, general features 50-51

Sundance formation in central southern Montana 17-20

Telegraph Creek formation in central south­ern Montana 35-36

Tensleep sandstone in central southern Mon-' tana 13-14

Thermopolis shale in central southern Mon­tana 27-30

Torchlight sandstone member of Frontier formation in central southern Montana, section of

Transportation facilities in central southern Montana..

33

6

U

Uinta formation near Vernal, Utah, bitu­minous sandstone in 81-93

Virgelle sandstone member of Eagle sandstone in central southern Montana 36--37

W

Wells in south central Montana drilled for oil. 59-62 White River group (?), Grand County, Colo. 73

Yellowstone County, Mont., coal in 63-67 correlation of geologic formations in, with

those in other areas pi. 2 drainage of 5-6 geology and mineral resources of parts of.. 1-70

map showing pi. 1 (in pocket) stratigraphy of, general features 7-9 water supplies in 7

l

k

o t

UNITED STATES DEPARTMENT OF THE INTERIOR RAY LYMAN WILBUR, Secretary

GEOLOGICAL SURVEY G E O R G E O T I S SMITH, Director

Bulletin 822

CONTRIBUTIONS TO ECONOMIC GEOLOGY

(Short Papers and Preliminary Reports)

1930

PART II

MINERAL FUELS

H. D. MISER GEOLOGIST I N C H A R G E

U N I T E D S T A T E S

G O V E R N M E N T P R I N T I N G OFFICE

W A S H I N G T O N : 1931

For sale by the Superintendent of Documents, Washington, D. C. Price 30 cents