Stratigraphy of the 

Morrison Formation 

In Part of Northwestern 

New Mexico

GEOLOGICAL SURVEY BULLETIN 1030-J

This report concerns work done on behalf 

of the U. S. Atomic Energy Commission 

and is published with the permission of 

the Commission

Stratigraphy of the 

Morrison Formation 

In Part of Northwestern 

New Mexico

By V. L. FREEMAN and L. S. HILPERT

CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

GEOLOGICAL SURVEY BULLETIN 1030-J

This report concerns work done on behalf 

of the U. S. Atomic Energy Commission 

and is published with the ^ permission of 

the Commission

UNITED STATES GOVERNMENT PRINTING OFFICE^ WASHINGTON : 1956
UNITED STATES DEPARTMENT OF THE INTERIOR 

Fred A. Seaton, Secretary

t . ' GEOLOGICAL SURVEY 

Thomas B. Nolan, Director

For sale by the Superintendent of Documents, U. S. Government Printing Office 

Washington 25, D. C. - Price 15 cents (paper cover)
CONTENTS

Page

Abstract.__._____...____________________________.__ 309

Introduction. _____________________________________________________ 309

Previous stratigraphic work_______________________________________ 310

Morrison formation in northwestern New Mexico_____________________ 313

Recapture member.___________________________________________ 313

Westwater Canyon member____-_____-___--______-__-_____ _ 314

Brushy Basin member..______________________________________ 314

Stratigraphy of the Morrison formation near Laguna.________________ 315

Conclusions_____________________________________________________ 318

Literature cited.__________________________________________________ 319

Stratigraphic sections of the Morrison formation.____________________ 320

ILLUSTRATIONS

FIGURE 58. Index map of part of New Mexico._______________________ 311

59. Nomenclature of the Morrison formation in northwestern

New Mexico...___________________________ 312

60. Nomenclature of the Morrison formation in the Laguna area. 315

61. Interrelationship of the members of the Morrison formation.. 316

in

CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

STRATIGRAPHY OF THE MORRISON FORMATION IN PART 

OF NORTHWESTERN NEW MEXICO

By V. L. FEEEMAN and L. S. HILPEET

ABSTRACT

In the summer of 1954 while investigating the uranium resources of northwestern New Mexico, the writers noticed that the stratigraphic nomenclature of 

the Morrison formation in use in the Laguna area was not consistent with that 

in use elsewhere in the region. A review of the literature led to the agreement 

that the nomenclature currently in use elsewhere in the area, such as near Grants, 

is satisfactory. This usage divides the Morrison formation into three members; 

in ascending order they are the Recapture, the Westwater Canyon, and the 

Brushy Basin members. These members may be recognized and have been 

correlated throughout northwestern New Mexico. In the Laguna area the Recapture, Westwater Canyon, and most of the Brushy Basin members, as correlated by the writers, are present in the stratigraphic interval that has previously 

been considered as Recapture. The sandstone previously considered as Westwater Canyon is in our opinion at the top of the Brushy Basin. This sandstone 

is of economic importance and is informally called the Jackpile ore-bearing bed.

INTRODUCTION

The field work on which this report is based was done during the 

summer of 1954 when the writers were engaged in investigating the 

uranium resources of northwestern New Mexico on behalf of the 

U. S. Atomic Energy Commission. While studying the uranium 

potential of the stratigraphic units, a discrepancy between the nomenclature of the Morrison formation of Late Jurassic age in the 

Laguna area and in other parts of northwestern New Mexico became 

evident. As correct correlations were a necessity in evaluating the 

resource potential of the stratigraphic units, a stratigraphic study 

was undertaken to assure proper correlations. Eleven stratigraphic 

sections were measured in northwestern New Mexico, four sections 

measured by others were examined, and a review of the literature was 

undertaken. This report reviews the names that have been proposed for the members of the Morrison formation in northwest New 

Mexico, describes them, and presents the results of the writers' work 

in correlating the members near Laguna with adjacent areas. The 

work was aided by the cooperation of the staffs of the mining companies in the area and the Atomic Energy Commission. Use was

309
310 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

made of stratigraphic sections measured by L. C. Craig and T. E. 

Mullens of the Geological Survey.

PREVIOUS STRATIGRAPHIC WORK

The nomenclature of the formations of Jurassic age in northwestern 

New Mexico was summarized, and a complete bibliography of the 

Jurassic literature was presented, by Baker, Dane, and Reeside (1936, 

p. 43). This report, together with a revision by them (1947), is the 

standard reference on Jurassic stratigraphy in the region. In the 

earlier paper the Morrison formation in northwestern New Mexico 

included the Todilto limestone member at the base, overlain in 

ascending order by a sandstone member and a shale member (Baker, 

Dane, and Eeeside, 1936, table 8). In the revision the Todilto limestone was not included in the Morrison formation (1947, p. 1668). 

No attempt was made in these reports to subdivide the Morrison 

formation above the Todilto limestone into formal members.

The first subdivision of the Morrison formation on the Colorado 

Plateau was made by Lupton (1941) who gave the name Salt Wash 

sandstone member to a basal conglomeratic sandstone unit in eastcentral Utah. At Bluff, Utah (fig. 58), a massive sandstone that 

forms the cliffs along the San Juan River, and locally referred to as 

the Bluff sandstone, was considered by Baker, Dane, and Reeside 

(1936, p. 21) as a member of the Morrison formation. Gregory 

(1938, p. 58), in the same area, recognized four members of the 

Morrison formation: the Bluff sandstone at the base, overlain by the 

Recapture shale, the Westwater Canyon sandstone, and the Brushy 

Basin shale.

In 1947 the Geological Survey began a study of the stratigraphy 

of the Morrison formation on the Colorado Plateau (Craig and others, 

1955). The study resulted in the definition of the distribution of the 

members of the Morrison formation in the Colorado Plateau region. 

As this study centered on the then known uranium ore deposits in 

the Morrison formation in western Colorado and eastern Utah, the 

Morrison formation of northwestern New Mexico was not investigated 

in detail. Craig tentatively assigned the Bluff sandstone, as a formation, to the upper part of the San Rafael group but retained as 

members of the Morrison formation in ascending order: the Salt Wash, 

Recapture, Westwater Canyon, and Brushy Basin. These assignments have been accepted by the Geologic Names Committee of the 

Geological Survey. The Salt Wash member was shown (Craig and 

others, 1955, p. 135, 138) to extend from southeastern Utah a short 

distance into New Mexico, where it intertongues southwardly with 

tjies,Recapture member and is absent elsewhere in New Mexico. The 

remaining members of the Morrison formation, the Recapture, West-
STRATIGRAPHY, MORRISON FORMATION, NW. NEW MEXICO 311

1

r

f

r1

~

J

0Bluff 

UTAH 

?IZONA~

n 

i

_ 

4i

__ _i_j

L

^ h-l ->, -1 /

COLORADO! \ _ ! _£ __ _. J.

T NEW MEXICO^ ~~ } j r 

(i L/

1 ' ' M " ^ ^ 1

AKEASHOWNONFId.fi r~ - \ ____ 1 ,

l ' x . r~i

Galiup ' | \ |

I f ~ ""oBTuewateAp __ L- - /S *~ 

I Grantso \oCanoncito | __ j

_ 1 Laguna0 ALBUQUERQUE ~ "~ 1 J | 

°Acoma ^^ H"| ' | _ r r

i L 1

r - i

I i i

i i I_ -L -J

L^ i 

i 50 0 100 Miles 

1 1 , . , , l , I

FIGUEE 58. Index map of part of New Mexico and adjacent States showing localities referred to in text.

water Canyon, and Brushy Basin, were shown to extend to and 

beyond the Laguna area.

Before the extension of the Recapture, Westwater Canyon, and 

Brushy Basin members of the Morrison formation into New Mexico, 

a set of informal member names was suggested by Kelley and Wood 

(1946) and adopted by Silver (1948) in the Laguna area. These 

names were, in ascending order: the buff shale, the brown-buff sandstone, the white sandstone, and the variegated shale. Craig considered the buff shale to be an equivalent of the Summerville formation 

and the brown-buff sandstone and the white sandstone to be equivalents of the Bluff sandstone (Craig, oral communication). The variegated shale apparently contains equivalents of the Recapture, Westwater Canyon, and Brushy Basin members.

The discovery of commercial quantities of uranium ore in northwestern New Mexico in 1950, resulted in a study of the sedimentary
312 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

rocks of Jurassic age by the Atomic Energy Commission (Rapaport, 

Hadfield, and Olsen, 1952). The geologists of the Atomic Energy 

Commission recognized the presence of the Summerville formation 

and Bluff sandstone in the area of northwestern New Mexico east of 

Gallup (Rapaport, Hadfield, and Olsen, 1952, p. 20) and followed 

Craig's (Craig and others, 1955) terminology for the Morrison formation (fig. 59). This terminology has been widely accepted by the 

mining companies.

Smith (1951, p. 13; 1954, p. 15) recently proposed a partly new 

set of names for the members of the Morrison formation (fig. 59). 

In the area near Thoreau, N. Mex., he divides the Morrison formation 

into the Chavez at the base, stating that it may be equivalent to the 

Recapture; an overlying Prewitt sandstone member, equivalent to the 

Westwater Canyon; and the Brushy Basin at the top. The writers 

believe that the similarity of the members of the Morrison in the

Baker, Dane, and Reeside 

1936, 1947 

Northwest New Mexico

Cretaceous

J

c

1

S

Shale member

Sandstone 

member

Todilto 

limestone 

member

Kelley and Wood 

1946 

Lucero uplift, 

New Mexico

Dakota (?) sandstone

g 

.1

I

Variegated 

shale 

member

White 

sandstone 

member

Brown-buff 

sandstone 

member

Buff 

shale 

member

Todilto 

gypsum 

member

Harshbarger, Repenning, 

and Jackson 

1951 

Navajo Country

Dakota sandstone

Brushy Basin 

shale member

Westwater Canyon 

.g sandstone member

1 

.1

Cow Springs 

sandstone

Recapture 

shale 

member

Salt 

Wash sandstone 

member

Bluff 

sandstone

Summerville 

formation

Absent

This report; modified from Craig 

and others, 1955; and 

Rapaport, Hadfield, and 

Olsen, 1952 '

Dakota sandstone

.0

.1 

§

Brushy Basin 

member

Westwater Canyon 

member

Salt 

Wash 

member

Recapture 

member

Bluff 

sandstone

Summerville 

formation

Todilto limestone

Smith, C.T. 

1954 

Thoreau quadrangle

Dakota sandstone

g 

is

1

i

3 

1

Brushy Basin 

shale member

Prewitt sandstone 

member

Chavez 

member

Upper member

Lower member

Todilto formation

FIGURE 59. Nomenclature of the Morrison formation in northwestern New Mexico.
STRATIGRAPHY, MORRISON FORMATION, NW. NEW MEXICO 313

Thoreau-Grants area with those in southeast Utah could only be 

possible if they are continuous beneath the San Juan Basin. It, 

therefore, seems desirable to use the same terminology, especially as 

it is in general use by the mining companies in northwest New Mexico, 

rather than adopt the new terminology of Smith. In summary, the 

Morrison formation throughout most of northwestern New Mexico is 

considered to consist of the Recapture at the base, the Westwater 

Canyon, and the Brushy Basin. A summary of the terminology is 

presented in figure 59.

MORRISON FORMATION IN NORTHWESTERN 

NEW MEXICO

In the belt of outcrop of the Jurassic rocks between Gallup and 

Albuquerque, the Morrison formation as used here consists of three 

conformable members: the Recapture, Westwater Canyon, and the 

Brushy Basin. To the west, on the Navajo Indian reservation, several 

upper Jurassic units grade into a sand facies that has been named the 

Cow Springs sandstone (Harshbarger, Repenning, and Jackson, 1951). 

At Lupton, Ariz., the Recapture and Westwater Canyon members of 

the Morrison are recognizable although with difficulty. Farther to the 

south the Recapture grades into the Cow Springs sandstone leaving 

only the Westwater Canyon as a recognizable member of the Morrison 

formation because the Brushy Basin is missing, probably due to preDakota erosion. About 3 miles east of Gallup where the Jurassic 

section crops out on the flank of the Zuni uplift, the Recapture is 

recognizable although it is very sandy. A few miles farther east the 

Brushy Basin appears beneath the Dakota sandstone of Cretaceous 

age, and in the area of this report the Morrison formation consists of 

the three members listed above.

BECAPTUBE MEMBEB

The Recapture member in the Gallup-Albuquerque area ranges 

from about 20 to about 170 feet in thickness, in general thinning 

southward. It consists largely of grayish-red sandy claystone and 

clayey sandstone with limy nodules and white, clean, fine- to mediumgrained sandstone in alternating units 5 to 10 feet in thickness. The 

clean sandstone beds are most common in the western part of the area 

and probably represent tongues of the Cow Springs sandstone. 

Clayey sandstone is the dominant rock type in the eastern and southern parts of the area. The Recapture in most of the area is conformable with the underlying Bluff sandstone, but to the north near San 

Ysidro it rests directly upon the Summerville formation. In general 

the upper part oi the usually clean Bluff sandstone is clayey, but the 

contact with grayish-red clayey sandstone of the overlying Recapture

402655 56 2
314 CONTRIBUTIONS TO THE GEOLOGY OF UttANIUM

is sharply marked. In the Laguna area the Recapture interfingers 

with the Bluff sandstone. On Haystack Butte, near Bluewater, the 

basal unit of the Recapture member is a conglomeratic sandstone that 

rests on a slightly channeled surface cut into the Bluff sandstone; they 

are distinguished by grain size and type of crossbedding.

The Recapture generally is overlain by the Westwater Canyon from 

which it is easily distinguished. A few miles south of Laguna the 

Recapture is composed of clayey sandstone beds that, because of the 

absence of the Westwater Canyon, are directly overlain by Brushy 

Basin strata of similar lithology. Near Acoma, farther to the southwest, the two members could not be separated with certainty.

WESTWATER CANYON MEMBER

The Westwater Canyon member ranges from about 50 to 190 feet 

in thickness in the Gallup-Albuquerque area, except near Laguna 

where it is locally absent. In general, the Westwater Canyon thickens from the Laguna area toward Gallup to the west and toward San 

Ysidro to the north. The Westwater Canyon is a yellowish-gray to 

light-grayish-red, locally conglomeratic, fine- to coarse-grained sandstone that is characterized by scour-and-fill crossbedding and by 

angular grains of unweathered feldspar. Discontinuous lenses of 

grayish-green sandy claystone are present. The Westwater Canyon 

interfingers with the underlying Recapture and the overlying Brushy 

Basin members.

BRUSHY BASIN MEMBER

The thickness of the Brushy Basin member is largely determined by 

the amount of deformation and erosion before deposition of the Dakota 

sandstone. The details of the pre-Dakota deformation are not known, 

but, in general, it consisted of northeastward tilting and local broad 

folding. Subsequent erosion resulted in a southwestward irregular 

thinning of the Brushy Basin. In northwestern New Mexico the 

member ranges in thickness from a knife edge to about 370 feet. The 

Brushy Basin consists of partly variegated but dominantly light 

greenish-gray, slightly swelling, locally sandy claystone containing 

limy nodules. Thick sandstone units lithologically similar to the 

Westwater Canyon, thin hard green sandstone beds, and thin clayey 

limestone beds are rare to common in occurrence. Pinkish-orange 

jasper commonly occurs, especially near the base, as crack fillings and 

as cement in thin sandstones. As the Brushy Basin and the Westwater Canyon members interfinger, the contact between the members 

may be difficult to determine. The writers placed the contact at the 

base of the lowest recognizable claystone in the Brushy Basin and 

acknowledge that some of the sandstone beds placed in the Brushy 

Basin may laterally be equivalent to the Westwater Canyon member:
STRATIGRAPHY, MORRISON FORMATION, NW. NEW MEXICO 315

STRATIGRAPHY OF THE MORRISON FORMATION NEAR

LAGUNA

The Morrison formation in the Laguna area became of economic 

importance with the discovery of uranium in 1951. As a consequence, 

a great deal of geologic work is in progress in the area. The nomenclature of the Morrison formation in general use is that used in this 

report, but it is not being applied to the same stratigraphic units. 

Figure 60 compares the terminology in previous use with that proposed

Previous usage This report

Dakota sandstone 

^ \_ 

Westwater Canyon member

Dakota sandstone

^_^^^^-

Jackpile ore-bearing bed

Recapture member Brushy Basin member

Westwater Canyon member

Recapture member

Bluff sandstone Bluff sandstone

FIGURE -Nomenclature of the Morrison formation in the Laguna area, New 

Mexico.

now. The correlation of the members of the Morrison formation 

between Laguna and adjacent areas is difficult because of: the similarity of the ore-bearing sandstone unit, informally called Jackpile 

ore-bearing bed in this report, with the Westwater Canyon member; 

the local absence of the Westwater Canyon; the unusual thickness of 

the Brushy Basin member; and the thinness and incomplete exposures 

of the Recapture member. The Salt wash member is not present in 

this area.
316 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Figure 61 shows the location of some of the measured sections studied 

and the relationship of the members of the Morrison between the 

sections. The sections used are presented following page 319. The 

Haystack Butte and Red Bluff sections are in the Grants area where 

there is general agreement on the nomenclature; At Haystack 

Butte the contact between the Westwater Canyon and the Brushy 

Basin is placed at the base of the lowest persistent claystone unit. 

Ledges of sandstone that could not be distinguished from the Westwater Canyon are present throughout the entire thickness of the 

Brushy Basin. Eastward toward the Red Bluff section the Westwater Canyon interfingers with the Brushy Basin and to a lesser extent 

with the Recapture, resulting in a considerable thinning of the WestHAYSTACK 

BUTTE 

Sec. 13, 

T. 13 N., 

R. 11 W. RED 

BLUFF 

Sec. 3, 

T. 12 N., 

,R.9W.

30 Miles

\\\

ACOMA SHEEP\\\ 

Sec. 8, CAMP \\\ 

T. 8 N., Sec. 2, \\\ ., 

R.7W. T.8N., \N ^- 

R.6W,

. 5 W.

INDEX MAP

NORTH OF

WEST MESA CARONCITO 

GIGANTE E.%,Sec.34, 

Sec. 10, T. 11 N 

T.10N., R.3W, 

R.4W.

FIGURE 61. Interrelationship of the members of the Morrison formation.

water Canyon. Interfingering of the Recapture with the Bluff 

sandstone was not seen but may be present and may account for some 

thinning of the Recapture. The Morrison formation is not exposed 

in the area between the Red Bluff and Laguna sections.

At the Laguna section, only the uppermost 29 feet of the Bluff 

sandstone is exposed. It is overlain by about 20 feet of reddishbrown and minor greenish-gray, very clayey sandstone with limy 

nodules that is typical of the Recapture member. Above the slope 

formed on the Recapture is a prominent ledge, about 55 feet thick, 

of the Westwater Canyon member. As no exposures of the Recapture 

exist between the Red Bluff and Laguna section, the manner of its 

thinning is not known. Silver (1948) showed that in this area the
STRATIGRAPHY, MORKISON FORMATION, NW. NEW MEXICO 317

entire Jurassic section thins southward by overlap against a Jurassic 

highland, and the writers believe the thinning of the Recapture is 

probably due to the same cause.

The Westwater Canyon is similar lithologically at the Laguna 

section and in the southeastern Utah area. It contains angular grains 

of unaltered feldspar, is moderately to poorly sorted, medium grained 

to coarse grained, and is scour-and-fill crossbedded. These features 

are in marked contrast to the dominantly well-sorted, fine-grained, 

and sweeping crossbedded Bluff sandstone that is not known to contain the angular grains of unaltered feldspar. South of Laguna the 

Westwater Canyon is not present; it probably disappears by interfingering with the Recapture and Brushy Basin members.

At the Laguna section the Brushy Basin member is about 370 feet 

thick. It consists of grayish-green, slightly swelling, clay-rich beds 

with some pinkish variegations near the base and lenticular sandstone 

units lithologically similar to the Westwater Canyon. The Brushy 

basin in the Laguna area is similar to the Brushy Basin in the Grants 

area and in southeastern Utah but distinctly different from the 

Recapture member in these areas. At the Laguna section the uppermost 65 feet of the Brushy Basin is the so-called Jackpile ore-bearing 

bed. It is a very pale orange and locally white sandstone that is 

dominantly fine grained to medium grained with minor coarse grains 

at the base. Feldspar grains, as well as specks of a white clay mineral, 

probably kaolin, are present. The sandstone is characterized by scourand-fill crossbedding, but some parallel bedding, often marked by 

claystone partings, is present also.

Toward Acoma, beytmd the limit of the Westwater Canyon member, the Recapture and Brushy Basin members are considerably 

thinner (fig. 61). The contact of the Recapture and Brushy Basin 

can be placed with reasonable certainty as far southwest as the Sheep 

Camp section (fig. 61), but farther to the southwest the contact is 

indistinct. The Brushy Basin becomes more variegated, grayish-red 

colors are prevalent, and it is similar to the Recapture. At the 

Acoma section a reddish zone at the base of the Morrison may correlate with the Recapture, but this zone is gradational with the upper 

part of the formation which also contains thin reddish zones.

The West Mesa Gigante section is similar to the Laguna section; 

but, proceeding from the section southward along the west side of 

Mesa Gigante the Westwater Canyon disappears in a few miles. It 

reappears for about a half a mile along the south face of the mesa 

where it has a thickness of 58 feet; it does not reappear again until 

about 3 miles north of Canoncito along the east face of the mesa 

where it is 47 feet thick. At this locality, S% sec. 27, T. 11 N., R. 

3 W., the pinching out of the Westwater Canyon is well exposed. In
318 CONTRIBUTIONS TO THE GEOLOGY OF.URANIUM

a distance of about 50 feet along the outcrop, the entire member, 

consisting of 47 feet of sandstone disappears by interfingering with 

sandy claystone beds similar to the Recapture and Brushy Basin 

(fig. 61). North of the Canoncito section, less than half a mile from 

the disappearance of the Westwater Canyon, the Recapture includes 

several sandstone beds similar to those in the Westwater Canyon. 

Between the Canoncito area and the Cuchillo Arroyo section, only 

the upper part of the Morrison is exposed locally. At Cuchillo 

Arroyo 170 feet of the Westwater Canyon is well exposed in a vertical 

 cliff. It interfingers at top and base with the Brushy Basin and 

Uecapture, respectively. The Recapture rests directly upon the 

Summerville formation from which it is distinguished with difficulty. 

The manner in which the Bluff sandstone has disappeared is not 

known, but as the Bluff has been seen by the writers to interfinger 

with both the Recapture member and the Summerville formation, a 

gradual thinning by interfingering with these units is at least partly 

responsible.

CONCLUSIONS

The Morrison formation in the area of Laguna, N. Mex., consists 

of a 20-foot unit at the base assigned to the Recapture, a 55-foot 

sandstone assigned to the Westwater Canyon, and a 370-foot unit 

assigned to the Brushy Basin. The upper 65 feet of the Brushy 

Basin is a sandstone that has been considered by others as the Westwater Canyon to which it is lithologicaily similar; the entire underlying Morrison, in consequence, was considered as Recapture. The 

members of the Morrison formation near Laguna are lithologicaily 

similar to the members in the area near Grants, where there is general 

agreement of nomenclature, and in the San Ysidro area, where they 

are so typical as to preclude disagreement. The Recapture and the 

Westwater Canyon, however, are thinner near Laguna because of 

proximity to the edge of their areas of deposition; and the Brushy 

Basin is much thicker, probably because of less removal before 

deposition of the Dakota sandstone.

The sandstone occupying the uppermost part of the Brushy Basin 

member has been traced from the Laguna section, in nearly continuous exposures, into the ore-bearing sandstone at the Jackpile 

mine of the Anaconda Copper Mining Co. It ranges in thickness 

from a knife edge, where cut out by pre-Dakota(?) erosion, to about 

175 feet at the Jackpile mine. Because of the economic importance 

of'this sandstone bed, it has been informally named the Jackpile 

ore-bearing bed of the Brushy Basin member.
STRATIGRAPHY, MORRISON FORMATION, NW. NEW MEXICO 319 

LITERATURE CITED

Baker, A. A., Dane, C. H., and Reeside, J. B., Jr., 1936, Correlation of the Jurassic 

formations of parts of Utah, Arizona, New Mexico, and Colorado: U. S. 

Geol. Survey Prof. Paper 183.

 1947, Revised correlation of Jurassic formations of parts of Utah, Arizona, 

New Mexico, and Colorado: Am. Assoc. Petroleum Geologists Bull., v. 31, 

p. 1664-1668.

Craig, L. C., and others, 1955, Stratigraphy of the Morrison and related formations, Colorado Plateau region, a preliminary report: U. S. Geol. Survey 

Bull. 1009-E.

Gregory, H. E., 1938, The San Juan country, a geographic and geologic reconnaissance of southeastern Utah: U. S. Geol. Survey Prof. Paper 188.

Harshbarger, J. W., Repenning, C. A., and Jackson, R. L., 1951, Jurassic stratigraphy of the Navajo country: N. Mex. Geol. Soc. Guidebook, 2d field 

conf., p. 95-99.

Kelley, V. C., and Wood, G. H., 1946, Lucero uplift, Valencia, Socorro, and 

Bernalillo Counties, N. Mex.: U. S. Geol. Survey Oil and Gas Inv. Prelim. 

Map 47.

Lupton, C. T., 1914, Oil and gas near Green River, Grand County, Utah: U. S. 

Geol. Survey Bull. 541-D.

Rapaport, Irving, Hadfield, J. P., and Olsen, R. H., 1952, Jurassic rocks of the 

Zuni uplift, New Mexico: U. S. Atomic Energy Comm., Tech. Inf. Service, 

RMO-642.

Silver, Caswell, 1948, Jurassic overlap in western New Mexico: Am. Assoc. 

Petroleum Geologists Bull., v. 32, p. 68-81.

Smith, C. T., 1951, Generalized nomenclature chart for formation and member 

names used in road logs: N. Mex. Geol. Soc. Guidebook, 2d field conf., 

p. 13.

 1954, Geology of the Thoreau Quadrangle, McKinley and Valencia 

Counties, N. Mex.: N. Mex. Bur. Mines and Min. Res., Bull. 31.
STRATIGRAPHIC SECTIONS OF THE 

MORRISON FORMATION

VALENCIA COUNTY

Laguna section, NWK sec. 28, T. 10 N., R. 5 W. 

[Measured by L. C. Craig, V. L. Freeman, and T. E. Mullins]

Top of measured section. fea 

Dakota sandstone:

Sandstone, white (M)) 1 , to very pale orange (10 YR 8/2), weathering 

grayish-orange (10 YR 7/4), fine- to medium-grained, well-sorted; 

composed of subrounded to rounded clear quartz with rare white 

accessory grains; well-cemented, calcareous; subparallel laminations filling shallow erosion troughs, thin- to medium-bedded, some 

ripple laminations. Conglomeratic sandstone near base, pebbles 

of gray and black chert, pebbles subangular to subrounded. Abundant plant impressions; some carbonaceous material. Unit forms 

vertical cliff_______________________________________ 16. 5

Morrison formation: 

Brushy Basin member:

Sandstone, very pale orange (10 YR 8/2), locally white (-ZV9) in upper 

part, predominantly fine- to medium-grained with rare coarse 

grains at base, well-sorted; composed of subangular to subrounded clear quartz with abundant pink feldspar grains and much 

interstitial kaolin; coarse grains are quartz, feldspar, granite, and 

rare red and brown chert; moderately well cemented; channeling 

with subparallel laminations filling erosion troughs; minor clay 

partings; unit forms ledgy slope with upper 16 feet forming a vertical cliff. (Jackpile ore-bearing bed)_________________________ 64. 5

Claystone, grayish-red (1QR 4/2) and light greenish-gray (5GY 8/1), 

very sandy (to fine-grained); earthy weathering; slightly fissile; 

forms banded slope________________________________________ 17. 8

Sandstone, very pale orange (10 YR 8/2) to yellowish-gray (5Y 8/1), 

medium- to coarse-grained, moderately sorted; composed of subrounded to rounded clear quartz with abundant pink and white 

accessory grains; friable, weakly cemented; bedding not visible; 

forms steep slope________________________________________ 12. 7

Claystone, grayish-red (10 R 4/2), very sandy (to fine-grained); earthy

weathering; slightly fissile__________-_____-___-________----_ 11. 8

Sandstone, with claystone and limestone near top; sandstone grayishyellow (5Y 8/4) to white (M)), medium-grained with some very 

coarse grains at top, moderately sorted; composed of subrounded 

quartz with common pink and white accessory grains; very coarse 

grains at top are predominantly clear to white quartz, pink feldspar, and granite; well-cemented to friable; cross-laminations 

filling erosion trougKs. Eight-foot claystone and limestone unit 

below 10-foot top ledge same as in unit below. Unit forms ledgy to 

rounded slope________________________________ 33. 7

i The colors and color numbers are from the Rock-color chart of the National Research Council, Washington, D. C., 1948.

320
STRATIGRAPHY, MORRISON FORMATION, NW. NEW MEXICO 321

Brushy Basin member Continued feet

Claystone, (90 percent) and limestone (10 percent). Claystone, 

dominantly light greenish-gray (5GY 8/1), with some yellowishgray (5F8/1) and at base pale-red (5R 4/2) to grayish-red (10R 

4/2), silty to sandy (fine-grained). Limestone, very light gray 

(NS), weathers white (JV9), dense to finely crystalline. Unit 

weathers to steep rubble-covered slope _______________________ 46. 4

Sandstone, conglomeratic, very pale orange (IQYR 8/2) to yellowishgray (5F8/1) very fine- to coarse-grained, poorly sorted; composed of subangular and subrounded clear quartz with abundant 

pink feldspar and uncommon white and green accessory grains. 

Conglomerate consists mainly of tan, brown, gray, and red chert 

pebbles and granules averaging % inch with maximum 1)4 inches 

in diameter, and abundant pink feldspar and white to clear quartz 

grains averaging % inch with maximum % inch in diameter; crosslaminations filling erosion troughs; locally forms prominent ledge. 

Coarser material concentrated at base of unit_________________ 14. 4

Claystone (85 percent), sandstone (10 percent), and limestone (5 percent). Claystone, yellowish-gray (5F8/1) to light greenish-gray 

(5G 8/1) and yellowish-gray (5Y7/2), slightly silty to slightly sandy 

(to fine-grained); frothy weathering, forms pastel green and pink 

slope. Sandstone, light greenish-gray (5G 8/1) to very light gray 

(NS), very fine grained; forms beds as much as 2 feet thick, 

bedding not visible; weathers to slabby ledges. Limestone, very 

light gray (N8), dense; forms nodular beds to hackly ledges 1 foot 

thick. Pink bands in claystone due to formation of pink cherty 

spots___________________________________________________ 64. 5

Sandstone (65 percent) and claystone (35 percent). Sandstone, yellowish-gray (5Y 8/1), fine- to medium-grained, moderately sorted; 

composed of subangular to subrounded clear quartz with common 

red, green, and white accessory grains; well-cemented with coarse 

crystals of calcite; unit is lenticular, beds 1 to 5 feet thick of wavy 

laminations and cross-laminations filling erosion troughs. Weathers to prominent ledges. Claystone, very light gray (NS), sandy 

(very fine- to fine-grained); hackly to earthy weathering, forms 

narrow slopes between ledges. Locally the sandstone contains 

dinosaur bones, gastroliths, and stringers of granule to pebble 

size reddish-brown subangular chert________________________ 48. 5

Claystone (70 percent), sandstone (15 percent), and limestone (15 percent). Claystone, variegated, dominantly yellowish-gray (5Y 

8/1), to light greenish-gray (5GF 8/1) containing thin beds of grayish-purple (5P 4/2) and grayish-red purple (5RP4/2) near the base, 

sandy; in part calcareous; frothy weathering. Sandstone, yellowish-gray (5F 8/1), fine- to very fine-grained, well-sorted; composed 

of subangular clear quartz with abundant pink and white and 

uncommon green accessory grains (pink probably feldspar); forms 

lenticular beds 1 to 10 feet thick pinching out laterally within 300 

feet, cross-laminations filling erosion troughs. Limestone, very 

light gray (NS) , weathers white (M)); forms hackly to concretionary rubble-covered slope_____________________---_----_ 58. 0

Total Brushv Basin member,___________________________ 372. 3
322 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Westwater Canyon member: Feel 

Sandstone, yellowish-gray (5F 7/2) to grayish-yellow (5F 8/4),mediumto coarse-grained with rare grains as much as one-eighth inch in 

diameter, poorly sorted; composed of subangular clear quartz 

with common pink feldspar, uncommon red and white accessory 

grains; firmly cemented, calcareous; medium scale wedging crosslaminations; forms prominent cliff above ledgy slope below. 

A lenticular bed at base is 1 foot thick, containing pebbles of red 

and gray chert and limy claystone. Limonite staining common- 56. 7

Total Westwater Canyon member._____________________ 56. 7

Recapture member:

Sandstone, clayey, and claystone, sandy, reddish-brown (1QR 3/4) and 

greenish-gray (5GF 7/1), fine- to medium-grained,poorly sorted; 

composed of subrounded stained quartz with uncommon orange 

and black accessory grains; calcareous; locally stained with 

limonite. At top of unit is zone of large (1 foot) nodules of 

radiating calcite_-__---_-_________----_---_-_-------------- 20. 1

Total Recapture member___________-__-_-__-____-----_- 20. 1

Total Morrison formation________________---_-----_-__- 449. 1

Bluff sandstone (part):

Sandstone, clayey, grayish-yellow (5F 8/4) to light greenish-gray 

(5GF 8/1), medium-grained, fair sorting; composed of subrounded 

grains of quartz with uncommon black and orange accessory 

grains; calcareous; bedding obscure. Becomes increasingly 

clayey upward. Limonite staining common. Weathers to 

gentle slopes or rounded ledges_____-_-_-__-__-----_--------- 29. 0

Base of measured section.

VALENCIA COUNTY

Acoma section, NW>£ sec. 8, T. 8 N, R. 7 W.

[Measured by V. L. Freeman, November 1954] 

Dakota sandstone:

Not measured or described. 

Top of section.

Morrison formation: y feet 

Sandstone, clayey, dusky red (5R 3/4) (30 percent) and light greenishgray (5(7F 8/1) (70 percent), gypsiferous, some limy nodules 

present. Unit contains minor sandstone beds like unit below. 

Unit forms slightly frothy surface__________________________ 36. 1

Sandstone, yellowish-gray (5F 8/1), medium- to fine-grained, wellsorted, subrounded, grains of quartz with uncommon red and 

orange accessory grains; friable, calcareous; very lenticular beds 

with minor beds of argillaceous sandstone like below except 

entirely dusky red; crossbedding is contorted low angle and 

medium scale, filling scour features._________________________ 7. 8

Sandstone, clayey, like top unit but 25 percent dusky red and 75

cent light greenish-gray____________________________________ 23. 7
STRATIGRAPHY, MORRISON FORMATION, NW. NEW MEXICO 323

Morrison formation Continued Feet

Sandstone, white (.ZV9), medium- to coarse-grained, conglomeratic, 

poorly sorted, grains of quartz with orange, red, and gray 

accessory grains, pebbles to one-half inch are of chert and clay 

(chert is mostly red with gray and green present); slightly friable, 

calcareous; crossbedding is low angle and medium scale, filling 

scour features___________________________________________ 3. 3

Sandstone, clayey, dusky red (5R 3/4) and light greenish-gray 

(5GY 8/1) in about equal amounts, fine-grained, poorly sorted, 

some limy nodules, minor amounts of sandy claystone and sandstone like below, forms slightly frothy surface.________________ 65. 4

Sandstone, yellowish-gray (5Y 8/1), medium-grained, well-sorted, 

subrounded, grains of quartz with uncommon red and orange 

accessory grains; friable, calcareous; very lenticular beds with 

some argillaceous sandstone like below near center of unit; 

contorted crossbedding is low angle and medium scale, filling 

scour features____-___________________-_______-___--_---__- 12. 0

Sandstone, clayey, dusky red (5JS 3/4), fine-grained, poorly sorted;

forms slightly frothy surface________________________________ 7. 0

NOTE. At least lowest unit is probably equivalent to Recaoture

member-____-___-___-__-_______-___--_--_----_-_------__- _____

Total Morrison formation______________________________ 155. 3

Bluff sandstone (part):

Sandstone, pale yellowish-green (10GY 8/2), fine-grained, well-sorted, 

subrounded grains of quartz with rare orange and red accessory 

grains; friable, some calcareous cement, some unknown white 

cement; unit weathers into rounded knobs; bedding not visible

Not measured 

Base of section.

Cuchillo arroyo section, sec. 36, T. 17 N., R. 1 W.

[Measured by L. C. Craig and V. L. Freeman, 1950]

Top of measured section.

Morrison formation (part):

Brushy Basin member (part): Feet 

Sandstone, very pale orange (IOYR 8/2), fine-grained, subangular, 

grains of clear quartz with uncommon orange and black accessory 

grains; hard, siliceous cement; lenticular strata, forms prominent 

local capping ledge_______________________________________ 2.5

Claystone,light greenish-gray (5GY 8/1), pale yellowish-brown (WYR 6/2), 

and pale reddish-brown (lOE 5/4), silty to medium-grained sandy, 

with common 1-inch to 1-foot beds of pale reddish-brown (WR 

5/4) and greenish-gray (5G 6/1) silicified claystone, several light 

gray (ZV7) dense lenticular limestone units; weathers to pastel 

green and pink; forms earthy to frothy slope-_________________ 58.3

Sandstone, light greenish-gray (5GY 8/1) to yellowish-gray (5F 8/1), 

fine-grained, subangular, well-sorted, grains of clear quartz with 

common orange, green, and black accessory grains; massive, forms 

resistant ledge, is locally highly lenticular___________________ 2.4
324 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Brushy Basin member (part) Continued Feet 

Claystone, light greenish-gray (5G 8/1) to light-gray (NT) with minor 

pale reddish-brown (WR 5/4) and pale yellowish-brown (WYR 

4/2) at top, silty to very fine grained sandy; weathers to earthy 

light greenish-gray slope with a few pale reddish-brown bands at 

top; one 6-inch lens of pale reddish-brown silicified Claystone or 

limestone near top_________-_______---_______-___-__-_____., 42.1

Total measured Brushy Basin member.__________________ 105.3

Total Brushy Basin member 2 _______________ 180.0

Westwater Canyon member:

Sandstone, light olive-gray (5F5/2) to yellowish-gray (5F8/1) to light 

greenish-gray (5GF 8/1), very fine-grained at top and coarsegrained at bottom, predominantly medium-grained, subangular 

to subrounded, grains of clear quartz with rare orange and black 

accessory grains; medium-scale cross laminated, scour bedding.

NOTE. Top four Westwater sandstone units appear transitional to

Brushy Basin member______________________________________ 22.5

Claystone, pale grayish-yellow (5F9/4) to pale greenish-gray (5G 6/1),

slightly silty to medium-grained sandy; weathers to earthy slope_ 5.4

Sandstone, grayish-orange (WYR 7/4) to yellowish-gray (5F 8/1), 

very fine-grained to medium-grained, subangular to rounded, 

poorly sorted, grains of clear quartz with rare orange and gray to 

black accessory grains; weakly cemented with streaks and bands 

of firm calcareous cement; medium-scale cross lamination indicated, scour bedding; forms ledgy slope______________________ 31.8

Claystone, greenish-gray (5GY 6/1), silty to slightly fine-grained 

sandy; weathers to earthy sandy slope, abundant very light gray 

(N8) dense to very fine-grained limestone nodules on surface-.-- 8. 6

Sandstone, pale yellowish-orange (10 FR 8/6) to yellowish-gray 

(5F 8/1) to white, fine- to medium-grained, subangular to subrounded, moderately sorted, grains of clear quartz with uncommon orange and white accessory grains, locally has specks 

of unknown white cement; medium-scale cross-laminated, channeling; lateral to section contains thin lenses of greenish claystone____________________________________________________ 85.5

Claystone, grayish-red (IOR 4/2) and light greenish-gray (5G 8/1)

with minor very fine- to fine-grained sandstone lenses-_________ 2. 5

Sandstone, pale yellowish-orange (10YR 8/6) r> to yellowish-gray 

(5F 8/1) to white (N9), fine- to medium-grained,-subangular to 

subrounded, moderately sorted, grains of clear quartz with uncommon orange and white accessory grains, locally has specks 

of unknown white cement; medium-scale cross-laminated, channeling ________________________ __ ________ 15. 0

Total Westwater Canyon member-_-__-_--____--_-_--__- 171. 3

2 Measured by E. H. Baltz, Jr., oral communication.
STRATIGRAPHY, MORRISON FORMATION, NW. NEW MEXICO 325

Recapture member: Fe&

Claystone, and sandstone (20 percent). Claystone, very dusky red 

(IQR 2/2), silty to slightly fine-grained sandy, structure partly 

masked, some thin irregular parallel beds; sandstone, light 

greenish-gray (5GY 8/1) to yellowish-gray (5Y 8/1), fine-grained, 

subangular,'moderately to poorly sorted, some interstitial clay, 

grains of clear quartz with uncommon orange and black and 

minor green accessory grains; in structureless beds 6 inches to 

3.5 feet thick;unit forms steep earthy slopes except under overlying cliff where it stands vertical____________________________ 25. 5

Sandstone and claystone, grayish-orange pink (IQR 8/2) and very 

minor greenish-gray (5GY 6/1), fine- to medium-grained, subangular to rounded, moderately sorted, grains of clear quartz 

with abundant orange and black and rare green accessory grains; 

medium-scale cross-lamination is indistinct; claystone, very 

dusky red (IQR 2/2) to grayish-red (IQR 4/2), silty to slightly 

sandy, structureless to thin parallel bedded; unit weathers to 

steep ledgy slope of white and yellowish gray with grayish-red 

bands______.________________.___________ 94. 0

Sandstone, and claystone (25 percent). Sandstone, grayish-orange pink 

(IQR 8/2), very fine- to medium-grained, moderately sorted, 

subangular to subrounded, grains of clear quartz with comnron 

black and orange accessory grains; several biotite flakes noted; 

medium-scale cross-laminations indistinct, local channeling; claystone, very dusky red (IQR 2/2) to grayish-red (10# 4/2), very 

slightly sandy up to fine-grained, finely micaceous, contains 

some thin sandstone beds, light greenish-gray (5GY 8/1) to 

grayish-red (IQR 4/2), very fine- to fine-grained, subangular, 

moderately sorted, grains of clear quartz with abundant orange 

and black accessory grains; structureless; unit as whole weathers 

to pale-red and grayish-red ledgy slope-______________________ 96. 5

Sandstone, white to moderate orange-pink (5YR 8/4), very fine- to 

medium-grained, moderately sorted, subangular to subrounded, 

grains of clear quartz with abundant orange and common black 

and rare green accessory grains; medium-scale cross-laminations 

indicated; unit weathers to sandy ledgy slope.________________ 13. 4

Claystone, very dusky red (IQR 2/2), grayish-purple (5P 4/2) and 

grayish-red (IQR 4/2); very fine- to medium-grained sandy; 

sandstone, light greenish-gray (5G 8/1) mottled grayish-red 

(5E 4/2), very fine- to fine-grained, rare medium grains, interstitial clay common, moderately to poorly sorted, subangular 

to rounded, grains of clear quartz with common orange, red, and 

black accessory grains; unit weathers to steep earthy slope_____ 47. 0

Total Recapture member______-____________-__-__---__- 276. 4

Summerville formation (part):

Claystone and sandstone. Claystone, dark reddish-brown (IQR 3/4) 

to pale reddish-brown, (10.R5/4) pure to very sandy, very fine- to 

fine-grained, earthy weathering; sandstone, pale reddish-brown 

(IQR 5/4) to grayish-orange pink (IQR 8/2), very fine- to finegrained, moderately sorted, subangular, weak to firm calcareous 

cement, grains of clear quartz with common black and orange 

accessory grains; units weathers to earthy slope_-.___.-Not measured

Base of section.
326 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

McKINLEY COUNTY 

Haystack Butte section, sec. 13, T. 13 N., R. 11 W.

[Measured by L. S. Hilpert and V. L. Freeman, August 1954]

Top of measured section.

Dakota sandstone (part): Feel

Sandstone, light reddish-orange (10.R 7/6), medium-grained, wellsorted, subrounded, grains of quartz with some white chert 

grains; friable, quartz overgrowths__ __ __ _ 40. 0

Shale, carbonaceous. Some interbedded clayey sandstone, grayish-red

(5R 4/2), medium-grained, poorly sorted, angular to subrounded-. 17. 8 

Morrison formation: 

Brushy Basin member:

Poorly exposed. Local outcrop of claystone, silty and sandy, light 

greenish-gray (5GY 8/1); and sandstone, pale yellowish-brown 

(1QYR 6/2), medium-grained, poorly sorted, subangular to subrounded, grains of quartz with red and white accessory grains; 

friable, calcareous cement and specks of white unknown cement_ 67. 2

Sandstone, slightly conglomeratic, pale yellowish-brown (10YR 6/2) 

with local greenish-gray (5GY 6/1), medium- to coarse-grained, 

poorly sorted, subangular to subrounded, grains of quartz with 

red and white accessory grains, granules and pebbles (% inch); 

friable, calcareous cement and specks of unknown white cement; 

crossbedding is medium scale and low angle filling shallow erosional troughs_________ _____ _ 2. 7

Claystone, silty and sandy, very dusky red (10R 2/2) and greenishgray (5GY 6/1)______________________________ 9. 6

Sandstone, like second unit below_______________________ __ 23. 2

Sandstone (at base) and claystone, silty. Sandstone, very pale orange 

(10 YR 8/2), fine-grained, poorly sorted, subrounded, grains of 

quartz with orange, black, and white accessory grains, possibly 

some silica cement; claystone, dusky red (10/2 3/2) ________ 6. 0

Sandstone, pale yellowish-brown (10F.R 6/2), very coarse-grained at 

base grading upward to medium-grained at top, poorly sorted, 

subangular to subrounded, grains of quartz with red and white 

accessory grains; very friable, calcareous near base, specks (1 to 

3 mm across) of unknown white cement scattered throughout; 

crossbedding is medium scale and low angle filling shallow erosional troughs______________ _______ _______ 18. 1

Claystone, silty, pale reddish-brown (1QR 5/4), mottled with yellowish

gray (5F 8/1)___________________________________ 24. 5

Total Brushy Basin member_________________________ 151. 3

Westwater Canyon member:

Sandstone, grayish-red (1QR 5/2) to light-brown (5YR 7/4) in lower

part and grayish-orange (1QYR 7/2) with some limonite stain near < 

top, poorly sorted, subrounded to rounded, grains of quartz with 

white, black, and orange accessory grains; locally calcareous in 

lower part; crossbedding is large scale and low angle filling shallow 

/ erosional troughs; mud pods and partings near base; this unit

forms a prominent cliflL________________________ 106. 0

Total Westwater Canyon member_______________________ 106. 0
STRATIGRAPHY, MORRISON FORMATION, NW. NEW MEXICO 327

Recapture member: Feet

Sandstone, very clayey, dark reddish-brown (10# 3/4) and light 

greenish-gray (5GY 8/1), fine-grained, poorly sorted with some 

coarse grains, subrounded, grains of quartz with orange, red, and 

black accessory grains; very calcareous near middle____________ 2. 5

Sandstone, yellowish-gray (5Y 8/1) and light olive-gray (5Y 6/1), finegrained, well-sorted, subrounded, grains of quartz with orange and 

black accessory grains; slightly calcareous, locally clayey; bedding 

obscure_________________________________________________ 5. 5

Sandstone, very clayey, dark reddish-brown (1QR 3/4) to grayishred (5R 5/2) with interbeds of pale olive (WY 6/2) near top, 

medium-grained, poorly sorted, subrounded, grains of quartz 

with orange and black accessory grains; calcareous with nodules 

near top________________________________________________ 18. 0

Sandstone, very light greenish-gray (5GY 9/1) to light pinkish-gray 

(5YR 9/1), fine- to medium-grained, poorly sorted, subrounded, 

grains of quartz with orange accessory grains; friable, calcareous; 

bedding obscure___-________________--___-___---___-_-_-_-_ 11. 2

Sandstone, very clayey, dark reddish-brown (10 R 3/4), fine-grained,

poorly sorted, subrounded______________________-__________- 10. 3

Sandstone, light yellowish-gray (5Y 9/1), medium- to coarse-grained, 

moderately sorted, subrounded to rounded, grains of quartz 

with white, orange, and black accessory grains; friable, slightly 

calcareous; at base are granules and pebbles ()_ inch) of red, black, 

and green chert; bedding mostly obscure, some crossbedding is 

medium scale, low angle, and some is straight in tabular sets____ 5. 9

Sandstone (75 percent) and claystone, sandy. Sandstone, yellowishgray (5Y 8/1) and pinkish-gray (5YR 8/1), fine-grained, moderately sorted, rounded, grains of quartz with orange and black 

accessory grains, locally green clay pods in sandstone at base, 

locally calcareous; claystone, pale yellowish-green (IOGY 7/2) 

with mottling of dark reddish-brown (10# 3/4) _ _ _ _ ___ ___ 15. 7

Claystone, sandy, like second unit below, contains some thin sandstone beds near top________________________________________ 6. 9

Sandstone, light yellowish-gray (5Y 9/1), medium-grained, moderately 

sorted, subrounded, grains of quartz with orange, red, and black 

accessory grains; very friable, calcareous especially near top and 

base; rare scattered pebbles near base; bedding obscure.-______ 5. 8

Claystone, sandy, mottled dark grayish-red (WR 3/2) and greenishgray (5GY 7/1), calcareous. Near middle of unit is 8-inch bed 

of sandstone, greenish-gray (5GY 7/1), very fine grained; friable, 

calcareous; thin parallel laminations_-_-___-___-----_--------- 7. 0

Sandstone, pale-red (10R 6/2) and pinkish-gray (5YR 8/1), mediumgrained with scattered granules and pebbles (1 inch) locally 

concentrated along laminae; moderately to poorly sorted, 

rounded; grains of quartz with orange, red, black, and green accessory grains; very friable, calcareous; claystone parting about 

7J4 feet above base; bedding mostly parallel but near base is crossbedding of medium to large scale and low angle that fills shallow 

erosional troughs_______________________________________-_-_44.4

Total Recapture member-_-_______-__-_-__-__-----._-__- 133. 2

Total Morrison formation._________________________ 390.5
328 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Bluff sandstone: Feet 

Sandstone, moderate orange-pink (10R 7/4) to light-brown (5YR 7/4), 

fine-grained, well-sorted, subrounded, grains of quartz with 

orange accessory grains; friable, calcareous; crossbedding is 

large scale and low angle in tabular sets; forms nearly vertical 

cliff _______________________________________________ Not measured

Base of section.

BERNALILLO COUNTY

North of Canoncito section, E^ sec. 34, T. 11 N., R. 3 W. 

[Measured by V. L. Freeman, October 1954]

Top of section. 

Dakota sandstone:

Not measured or described. 

Morrison formation:

Brushy Basin member: Fed 

Claystone, sandy, light greenish-gray (5G 8/1), minor amounts of 

sandstone and limy nodules, forms frothy surface. Poorly exposed, especially near top________________________________ 176.0

Sandstone, yellowish-gray (5F 8/1), medium-grained, moderately 

sorted, subrounded, grains of clay coated quartz with orange, 

black, and white accessory grains, quartz, clay, and calcite 

cement; bedding indistinct but in part is crossbedded on medium 

scale_____________________________________________________ 11. 7

Claystone, sandy, and sandstone, clayey, yellowish-gray (5Y 8/1) to 

light brownish-gray (5YR 6/1) with minor greenish tint; some 

limy nodules and chert; forms slightly frothy surface.___________ 52. 6

Total Brushy Basin member____________-_-_---------__- 240. 3

Gradational contact

Recapture member (probably includes equivalents to Westwater Canyon 

member):

Sandstone, partly clayey, yellowish-gray (5 Y 8/1) with limonite stains 

near base, fine- to medium-grained, moderately sorted; friable, 

calcareous especially near base; bedding not visible..__________ 14 5

Claystone, very sandy (to medium-grained), grayish-red (10R 4/2), 

calcareous. Unit contains one thin hard green sandstone bed; 

forms slightly frothy surface_________-_---_------_---------- 24 2

Sandstone, moderate orange-pink (SYR 8/4) to yellowish-gray (5Y 

8/1), medium-grained, poorly sorted, rounded, grains of quartz 

with uncommon black and orange accessory grains; friable, calr 

careous cement and uncommon specks of unknown white cement; 

crossbedding is small to medium scale________-_-_------_----_ 10. 1

Claystone, very sandy and sandstone, clayey; grayish-red (10.R 4/2), 

calcareous; sandstone in thin irregular beds totaling about half of 

unit________________ _ _____________________ 20. 0

Sandstone, yellowish-gray (5F 8/1), medium-grained, moderately 

sorted, rounded, grains of quartz with common black, orange, 

red, and white accessory grains; alternating hard and friable 

zones, calcite cement; bedding not visible___-_---_--_--------- 5. 4

Claystone, very sandy, like second unit below.____________________ 10. 5
STRATIGRAPHY, MORRISON FORMATION, NW. NEW MEXICO 329

Recapture member Continued Feet 

Sandstone, yellowish-gray (5Y 8/1), fine-grained, poorly sorted, 

rounded, grains of quartz with uncommon orange, red, black, 

and white accessory grains; slightly friable, calcareous; structureless; common limonite staining. Unit grades into unit above. __ 18. 0 

Claystone, very sandy (to medium-grained), grayish-red (IOR 4/2), calcareous, several irregular thin beds of sand3tone__-____---_--_- 12. 6

Total Recapture member and probable equivalents of Westwater Canyon member_________..___________-_-----_ 115. 3

Total Morrison formation__________.._______________-__- 355. 6

Bluff sandstone (part):

Sandstone, grayish-yellow (55^7/4), fine-grained, well-sorted, rounded, 

grains of quartz with black, white, and orange accessory grains; 

friable; bedding indistinct but in part is extremely large-scale 

crossbedding______________________ _________________ Not measured

Base of section.

Red Bluff section, WJ4 sec. 3, T. 12 N., R. 9 W.

[Measured by V. L. Freeman and L. S. Hilpert, August 1954]

Top of measured section.

Dakota sandstone (part): Fe*t 

Sandstone, very pale orange (1QYR 8/2), to dark yellowish-orange 

(10YR 6/6), the yellow coloring caused by limonite staining generally along bedding, medium-grained, poorly sorted with local 

scattered granules and pebbles of red and black chert and vein 

quartz, subangular to rounded, grains of quartz with rare chert 

and white accessory grains; abundant quartz overgrowths; parallel bedded with some tabular crossbedding__________________ 49. 0

Morrison formation: 

Brushy Basin member:

Claystone and sandstone, clayey, poorly exposed; greenish-gray 

(5GY 6/1) at base and pale-olive (10F 6/2); local calcareous thinbedded sandstone lenses, greenish-gray (5GY 6/1), fine-grained-_ 88. 0 

Sandstone, pale yellowish-brown (IQYR 7/2), medium- to coarsegrained, poorly sorted with local granules and small pebbles, 

subangular to rounded, grains of quartz with uncommon orange 

and black accessory grains; crystal calcite cement at top and 

specks of unknown white cement throughout; cross-laminations 

are medium scale and low angle filling shallow erosion troughs__ 14. 4 

Mostly covered; some claystone, yellowish-gray (5F 8/1) and light 

greenish-gray (5GY 8/1), free of sand grains, some limy nodules, 

some seams of gypsum_____________________________________ 42. 6

Sandstone, yellowish-gray (5F 8/1), medium-grained, poorly sorted, 

rounded, grains of quartz with white, black, green, and orange 

accessory grains; friable, calcareous; forms surface coated by 

small nodules. _____________________________________________ 4. 0

Claystone, slightly sandy, grayish-yellow green (5GY 7/2) and light

grayish-red (IOR 5/2) in lower part, common limy nodules.___ 10. 6
330 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Westwater Canyon member: Fe& 

Sandstone, grayish-orange (10YR 7/4) with widespread limonite 

specks, medium- to coarse-grained, moderately to poorly sorted 

with scattered granules, subrounded, grains of quartz with 

common white (kaolin?) and rare black (chert?) accessory grains; 

friable, local crystal calcite cement; cross laminations are medium 

scale and low angle between planar erosion surfaces. Locally 

claystone, pale yellowish-green (1QGY 7/2) occurs near the base 

in irregular pods______________________________ 62. 2

Total Westwater Canyon member. _ ____ ____ 62. 2 

Recapture member:

Sandstone, clayey, and some claystone, sandy, dusky red-purple 

(5RP3/2) and greenish-gray (5GYQ/1), sandstone is fine grained, 

claystone locally contains limy nodules; unit forms mostly 

covered slope___________________________ _____________ 25. 9

Sandstone, light yellowish-gray (5Y 9/1), fine- to coarse-grained, local 

conglomeratic lenses with pebbles dominantly of chert, moderately to poorly sorted, subrounded, grains of quartz with white, 

orange, and black accessory grains; crystal calcite cement; crossbedding filling scours________________ ________ 7. 4

Sandstone, clayey, and claystone, sandy. Claystone mostly light 

greenish-gray (5GY 8/1) and brownish-gray (5YR 4/1) with some 

grayish-red purple (5RP 4/2) and dusky yellow (5F 6/4); sandstone 

is fine grained and poorly sorted; local limy nodules._____ 3. 0

Sandstone, light yellowish-gray (5F 9/1), medium-grained, poorly 

sorted, rounded, grains of quartz with white and orange accessory 

grains, scattered granules and green clay chips; friable, locally 

calcareous; bedding obscure; weathers to rounded ledge_______ 9. 0

Sandstone, clayey, very dusky red purple (5RP 2/2), very fine- to 

fine-grained, moderately sorted, grains of quartz with black and 

orange accessory grains; local small limy nodules. Unit contains 

local thin beds of sandstone, greenish-gray (1QGY 5/2); hard, 

clay cement_____________________________________________ 7. 5

Sandstone, light yellowish-gray (5Y 9/1) and very light greenish .gray 

(5GY 9/1), fine- to medium-grained, poorly sorted, subrounded, 

grains of quartz with white, orange, red, green, and black accessory grains; friable; crossbedding is small to medium scale and 

low angle in tabular sets between planar erosion surfaces______ 8. 5

Sandstone, lenticular with thin irregular lenses and pods of claystone; 

claystone, dark reddish-brown (WR 3/4) mottled light greenishgray (5GY8/1); sandstone, light pinkish-gray (SYR 9/1), mediumto coarse-grained with scattered granules, poorly sorted, subrounded to rounded, grains of quartz with orange and black 

accessory grains; friable, calcareous; crossbedding is small scale 

and low angle in wedge-shaped sets_______________ __ 3. 9

Sandstone, light pinkish-gray (5YR 9/1), medium- to coarse-grained 

with rare granules, poorly sorted, subrounded to rounded, grains 

of quartz and chert with white and orange accessory grains; friable; in part is parallel bedded and in part is crossbedded, medium 

scale, low angle. This unit fills a channel in underlying unit that 

is 2 to 4 feet deep and about 20 feet wide___________________ 11. 0
(STRATIGRAPHY, MORRISON FORMATION, NW. NEW MEXICO 331

Recapture member Continued Fat 

Sandstone, slightly clayey, greenish-gray (5GF6/1), medium-grained, 

moderately sorted, rounded, grains of quartz with uncommon 

orange and red and rare black accessory grains; forms slope_____ 1. 3

Claystone, slightly silty, very dusky red (1QR 2/3); some limy nodules

and gypsum; forms rounded slope___._____._________________ 4. 3

Sandstone, slightly clayey, pale olive (10 Y 6/2) with some limonite 

stains, fine- to medium-grained, moderately sorted, rounded, 

grains of quartz plus common orange and rare black accessory 

grains; very friable; forms slope. Unit appears gradational 

with Bluff sandstone_____________________________________ 8. 8

Total Recapture member_____________._________________ 90. 6

Total Morrison formation.________________________ 312.4

Bluff sandstone (part):

Sandstone, grayish-yellow (5Y 8/4), fine- to medium-grained; very 

friable, calcareous concretions locally present; cross-laminations 

are medium to large scale and high angle in wedge-shaped sets__ Not

measured 

Base of section.

VALENCIA COUNTY

Sheep Camp section, S}_ sec. 2, T. 8 N., R. 6 W.

[Measured by V. L. Freeman, September 1954] 

Top of measured section. 

Dakota sandstone (part): Feet

Sandstone, like basal Dakota unit, two silicified 6-inch bands, also a few

very thin carbonaceous claystone partings ____________________ 15. 0

Claystone, carbonaceous, sandy. Along strike, unit becomes sandstone like below with very thin partings of carbonaceous claystone. Unit forms reentrant in cliff_______.._________________ 1.0

Sandstone, light-yellow (5Y 8/6), medium-grained, poorly sorted, 

granules common, rounded, grains of clay-coated quartz with 

white (chert?) accessory grains; one 6-inch band is highly silicified 

and white; very thin crossbedding is medium scale and low angle. 

Plant remains present.________-___--_-__-._________________ 4. 9

Morrison formation:

Claystone, slightly fine-grained sandy, pale-olive (105^6/2) and minor

grayish-red purple; forms slightly frothy surface_______________ 43. 5

Sandstone, white (-V9), medium-grained, well to moderately sorted, 

subrounded, grains of quartz with orange and white accessory 

grains; slightly friable, calcareous cement; indistinct crossbedding 

is medium scale and low angle_____________________________ 6. 0

Claysfone, like second unit below with two thin beds of sandstone,

like below, that total 3 feet_______---_-___.._______-___ 25. 7

Sandstone, white (M)), medium-grained, well to moderately sorted, 

subrounded, grains of quartz with orange and white accessory 

grains; slightly friable, calcareous cement; indistinct crossbedding 

is medium scale and low angle____________.._________________ 4. 6

Claystone, slightly fine-grained sandy, pale-olive (10 Y 6/2) and minor

grayish-red purple (5RP 4/2); forms slightly frothy surface____ 13. 0
332 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Morrison formation Continued ffeet

Sandstone, very light greenish gray (5GY 8/1), fine- to mediumgrained, well- to moderately sorted, subrounded, grains of quartz 

with orange and white accessory grains; slightly friable, calcareous 

cement; crossbedding is medium scale and low angle. Uncommon 

limy nodules. Unit is lenticular and interfingers with unit above. 8. 5

Sandstone, clayey, very dusky red (between 5RP 2/2 and 1QR 2/2) and 

light greenish-gray (5GY 8/1) in about equal amounts in alternating bands, medium-grained, moderately sorted, subrounded, 

grains of quartz and rare orange accessory grains; hard when 

fresh; unit forms soft slope. Laterally unit contains lens like 

unit above____________________________________________ 16. 8

Sandstone, clayey, dark reddish-brown (10R 3/5), fine-grained, 

moderately sorted, subrounded, grains of stained quartz with 

rare black accessory grains; hard when fresh; unit forms soft 

slope. Unit grades into Bluff sandstone and locally interfingers 

with Bluff________________________________ 3. 7

NOTE. Lower two units of Morrison probably are equivalent to Recapture member and remainder probably equivalent to Brushy 

Basin member___________________________________________ _____

Total Morrison formation.-__-_____________________ 121.8

Bluff sandstone (part):

Sandstone, light greenish-yellow (10 Y 7/2) slightly lighter near top, 

medium- and fine-grained in gradationally alternating 6-inch 

beds, well sorted to moderately sorted, subrounded to rounded, 

grains of green clay coated quartz with common white chert and rare 

orange accessory grains; friable, zones of heavy Hmonite cement. 

Poorly defined parallel bedding underlain by crossbedding of 

extremely large scale and low angle._________________ Not measured

Base of section.

VALENCIA COUNTY 

West Mesa Gigante section (composite) 

[Measured by V. L. Freeman, September, October 1954]

Section A., sec. 10, T. 10 N., R. 4 W. 

Top of section.

Dakota sandstone: Feet 

Not measured. Sandstone, conglomeratic, with minor carbonaceous

shale. Siliceous cement. 

Morrison formation: 

Brushy Basin member:

Sandstone, yellowish-gray (5Y 8/1) to white (-AT9), medium-grained, 

well to poorly sorted, subrounded to subangular, grains of £lay 

coated quartz with rare pink and black accessory grains, green 

clay chips locally abundant but usually rare; friable, some calcareous cement and specks of white unknown cement; crossbedding is medium scale and low angle filling shallow erosion 

troughs. This is the Jackpile ore-bearing bed._______________ 90. 9

Claystone, silty, and siltstone, clayey, light greenish-gray (50? F 8/1) 

and minor grayish-red (10/2 4/2), limy nodules common. Near 

top is 2-foot bed of sandstone, clayey, light grayish-green 

(5GT6/2)______________________________________________ 105.7
STRATIGRAPHY, MORRISON FORMATION, NW. NEW MEXICO 333

Brushy Basin member Continued Feet

Sandstone, yellowish-gray (5Y 8/1), medium-grained, poorly sorted, 

subrounded to subangular, grains of clay coated quartz with 

orange, red, black, and rare green accessory grains; granules 

and pebbles 0-4 inch) scattered in sandstone, include feldspar; 

crossbedding is medium scale and low angle, filling shallow 

erosion troughs___________________________________________ 20. 0

Claystone, silty; siltstone and very fine sandstone, both very clayey; 

all light greenish gray (50 8/1), some hard calcareous beds, 

weathers to frothy surface, _________________________________ 71. 7

Sandstone, very pale orange (10 YR 8/2) to dark yellowish-brown 

(10 YR 3/4), medium-grained, moderately sorted, grains of quartz 

with green, orange, red, and black accessory grains; hard; crossbedding is medium scale and low angle. Three beds with clay 

chips at base of each__-_______________________________-____ 3.0

Siltstone and very fine sandstone; both clayey, pinkish-gray (5YR 8/1) 

and light greenish-gray (5GY 8/1), calcareous; also claystone, 

silty, light greenish-gray (5GY 8/1) and minor pale-purple 

(5P 6/2), hard, calcareous; some units weather to frothy surface. 81. 2

Total Brushy Basin member.__________^________________ 372. 5

Section B, SW}i sec. 23, T. 10 N., R. 4 W.

Morrison formation Continued 

Westwater Canyon member:

Sandstone, very pale orange (10 YR 8/2) to dusky yellow (5F 6/4), 

medium- to coarse-grained, poorly to moderately sorted, subrounded to angular, grains of quartz and feldspar (angular and 

as much as granules in size) with common red and white (chert?) 

accessory grains; some beds clayey; friable except for local 

crystal calcite cement. Indistinct crossbedding_______________ 31. 1

Sandstone, like purple part of third unit below____________________ 1. 5

Sandstone (75 percent) and claystone with limy nodules (25). Sandstone, very pale orange (WYR 8/2), medium- to coarse-grained, 

moderately sorted, rounded to subrounded, grains of quartz and 

feldspar with common red and white and uncommon green and 

gray accessory grains; friable, calcareous, locally crystal calcite 

cement; crossbedding is small to medium scale, low angle, lenticular type; claystone like below but pale purple (5P 7/2) and with 

large (1 foot) nodules that form bed_________________________ 19. 5

Total Westwater Canyon member_______________________ 52. 1

Note. On section A where base is not exposed, the incomplete Westwater Canyon is 62 feet thick. 

Recapture member:

Claystone, slightly fine-grained sandy, light greenish-gray (5(? 8/1) 

with purplish tints locally, limy nodular beds total 2.0 feet. 

Claystone is slightly calcareous______________________________ 8. 3

Sandstone, very clayey, pale yellowish-green (WGY 7/2) in middle 

third, rest is grayish red-purple (5RP 4/2). Medium-grained, 

poorly sorted, rounded, grains of quartz with common orange 

and red and rare black and white accessory grains. Purple part 

is calcareous. Bedding obscure__-_________-_-___--__--__-_- 5.8
334 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

Recapture member Continued Ftet 

Claystone, very sandy (fine-grained) (50 percent) and sandstone (50 percent). Claystone, reddish-brown (10R 4/4), slightly calcareous but not 

containing limy nodules here; sandstone, yellowish gray, mediumgrained, moderately sorted, rounded, grains of quartz with 

uncommon orange, black, and red accessory grains; bedding 

obscure. Sandstone and Claystone thickly (2 to 3 feet) interbedded. Claystone beds weather to slightly frothy surface. ____ 31. &

Total Recapture member__._______________________ 45. 7

Total Morrison f ormation. _ _ ___________ _ __ 470. $

Bluff sandstone (part):

Sandstone, grayish-yellow (5F 8/4) to moderate yellow (5Y 7/6), 

medium-grained, well to moderately sorted, rounded grains of 

quartz with black, orange, and white accessory grains; friable, 

local crystal calcite cement. Crossbedding is large scale and 

poorly defined--..____________________ Not measured

Base of section.

o