GEOLOGICAL SURVEY CIRCULAR 360

GEOLOGY AND GROUND-WATER SUPPLIES 

OF THE FORT WINGATE INDIAN SCHOOL 

AREA, McKINLEY COUNTY, NEW MEXICO

PROPERTY OT§

tJ. B. EED! DGJCAL' SURVEY 

PUBLIC INQUIRIES OFFICE 

BAN FRANC1ECQ. CALIFORNIA

Prepared in cooperation with the Bureau of Indian Affairs

UNITED STATES DEPARTMENT OF THE INTERIOR 

Douglas McKay, Secretary

GEOLOGICAL SURVEY 

W. E. Wrather, Director

GEOLOGICAL SURVEY CIRCULAR 360

GEOLOGY AND GROUND-WATER SUPPLIES OF THE FORT WINGATE 

INDIAN SCHOOL AREA, McKINLEY COUNTY, NEW MEXICO

By J. T. Callahan and R. L. Cushman

Prepared in cooperation with the Bureau of Indian Affairs

Washington, D. C-, 1905

Free on application to the Geological Survey, Washington 25, D. C.

GEOLOGY AND GROUND-WATER SUPPLIES OF THE FORT WINGATE 

INDIAN SCHOOL AREA, McKINLEY COUNTY, NEW MEXICO

By J. T. Callahan and R. L. Cushman

CONTENTS

Abstract....................................................

Introduction...............................................

Location, topography, and drainage...............

Geology and ground-water resources..............

Geologic formations and their water-bearing 

properties........................................

Permian system...................................

San Andres formation.........................

Glorieta sandstone member..............

Limestone member.........................

Triassic system...................................

Moenkopi formation............................

Shinarump conglomerate.....................

Chinle formation................................

Geologic structures..................................

Folded rocks........................................

Page

1

2

2

2

2

4

4

4

4

4

4

4

4

5

5

Page

Geology and ground-water resources--Continued 

Geologic structures--Continued

Faults..,................................................. 5

Ground water................................................ 5

San Andres formation.................................. 5

Recharge conditions................................. 5

Discharge conditions................................ 6

Chinle formation........................................ 6

Recharge conditions................................. 6

Discharge conditions................................ 6

Hydrologic character of the San Andres

f o rma tion............................................... 6

Future development...... .............................. 7

Quality of water............................................ 7

Conclusions.................................................. 7

Literature cited............................................ 8

ILLUSTRATIONS

Figure 1. Map of Navajo country showing location of Fort Wingate Indian School area..............................

2. Map of Fort Wingate Indian School area, New Mexico, showing location of wells and springs and 

recharge and discharge areas of the San Andres formation.................................................

3. Generalized geologic cross section of the Fort Wingate Indian School area, showing aquifers......

Page

2

3

5

TABLES

Table 1. Well and spring discharge, depth of wells, and aquifers in the Fort Wingate Indian School area. 

2. Analyses of water from wells and springs in the Fort Wingate Indian School area and vicinity...

Page

8

9

ABSTRACT

A study of the local geology in relation to groundwater occurrence was made in the vicinity of the Fort 

Wingate Indian School which lies in McKinley County, 

N. Mex., just east of the town of Gallup.

The geologic formations studied range in age from 

Permian to Triassic. The San Andres formation of 

Permian age is composed of the Glorieta sandstone 

member and an overlying limestone member. The formation, which contains water under artesian conditions, is a single aquifer because water occurs in both 

the sandstone and the limestone members and no impermeable strata separate them.

Other formations present in the area, all of Triassic 

age, are the Moenkopi formation, the Shinarump conglomerate, and the Chinle formation. These three relatively impermeable formations confine the water in the

underlying San Andres formation. Three water-bearing 

sandstones are present in the Chinle formation. The 

authors believe that the production of large amounts of 

water from these sandstone beds is impractical.

The recharge a*-ea for the San Andres formation lies 

higher in the Zuni Mountains, immediately south of the 

Fort Wingate Indian School, and includes some 80 

square miles. The recharge area for the Chinle formation consists of narrow bands of sandstone in and near 

the school lands. These sandstones are recharged by 

relatively small amounts of water.

Water from the San Andres formation differs in chemical constituents from that of the Chinle formation. Water from the San Andres formation is very hard and contains several hundred parts per million of sulfate. Water from sandstone of the Chinle formation is only moderately hard, but it contains increasingly greater 

amounts of dissolved solids downdip from the recharge 

areas.
GROUND WATER OF THE FORT WINGATE INDIAN SCHOOL AREA, N. MEX.

Probable reasons are given for the wide range in the 

amount of flow from the several wells that penetrate 

the San Andres formation, and suggestions are given 

to guide future ground-water development from the 

San Andres formation.

INTRODUCTION

At the request of the Navajo Service, Bureau of Indian Affairs, a ground-water investigation was made 

in the vicinity of the Fort Wingate Indian School in 

McKinley County, N. Mex. (fig. 1), to learn more 

about the water-bearing characteristics of the aquifers 

in the area, particularly the San Andres formation.

This investigation is a part of the study of the 

ground-water resources of the Navajo and Hopi Indian 

Reservations now being made by the U. S. Geological 

Survey. The results of this study precede a complete 

report on the ground-water resources of the Navajo 

country. The work was financed by, and was in cooperation with, the Navajo Service, Bureau of Indian 

Affairs.

Fieldwork in this area was begun in October 1950 

and continued intermittently until October 1953. The 

work was under the direct supervision of J. W. Harshbarger, Navajo Project geologist, and under the general supervision of L. C. Halpenny, district engineer 

of the Ground Water Branch of the Geological Survey 

for Arizona. The fieldwork was begun by H. A. Whitcomb and R. L. Jackson and completed by the authors. 

The investigation consisted of a geologic reconnaissance, measurement of the discharge of springs and 

wells, and collection and chemical analysis of water 

samples.

of the Zuni Mountains and form a southward-trending 

hogback. The land surface south of the area slopes 

upward to the crest of the Zuni Mountains.

Drainage in the area is controlled by the geologic 

structure and topography. Surface water drains northward down the dip slope of the strata and through 

breaches in the cuestas to the Rio Puerco just south of 

U. S. Highway 66, and then westward to the Little Colorado River. Springs at the Fort Wingate Indian School, 

the Navajo Service Sheep Laboratory (about 2 miles 

southwest of the school), and in the canyons to the south 

maintain perennial streamflow in the upper reaches of 

the washes. Surface-water runoff reaches the Rio 

Puerco only after heavy rainfall. Washes not fed by 

springs are dry throughout most of the year and carry 

surface flow only after rains or during periods of melting snow.

GEOLOGY AND GROUND-WATER RESOURCES

Geologic Formations and their Water-Bearing 

Properties

The rocks of importance to an investigation of the 

ground-water resources in the Fort Wingate Indian 

School area range in age from Permian to Late Triassic. The formations concerned are listed in the 

stratigraphic column below, together with the probable 

maximum thickness and the water-bearing character 

of each. A more detailed stratigraphic section is given 

on page 10. Rocks of Jurassic and Cretaceous ages 

are exposed on the western and northern edges of this 

area but are not a source of water for the area. Thus, 

they have no influence on the water problems of the area 

and are not discussed further in this report.

NEW 

MEXICO

Figure 1. --Map of Navajo country showing location of Fort Wingate Indian School area.

LOCATION, TOPOGRAPHY, AND DRAINAGE

The Fort Wingate Indian School is located on 

Government-allotted land in McKinley County, N. Mex. 

about 12 miles east of Gallup, N. Mex., and 3 miles 

south of U. S. Highway 66 (fig. 2). The area is in a 

broad valley cut into the northern slope of the Zuni 

Mountains. To the north the valley is rimmed by the 

high escarpment of a cuesta formed by erosion of 

northward-dipping strata. A series of lower cuestas 

parallel the cuesta of the high escarpment. West of 

the area these cuestas merge around the north flank

Formation

Chinle formation...........

Shinarump conglomerate.

San Andres formation: 

Limestone member.....

Glorieta sandstone 

member.

Age

Triassic

.....do...., 

.....do.....

Permian 

.....do...,

Character

Waterbearing in part 

.....do..... 

Nonwater 

bearing

Water 

bearing 

.....do.....

Thickness 

(feet)

1,600

50 

34

100 

200
GEOLOGY AND GROUND-WATER RESOURCES

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Figure 2. --Map of Fort Wingate Indian School area. New Mexico, showing location of wells and springs and 

recharge and discharge areas of the San Andres formation.
GROUND WATER OF THE FORT WINGATE INDIAN SCHOOL AREA, N. MEX.

Permian System 

San Andres formation

The San Andres formation (Lee and Girty, 1909), 

composed of the Glorieta sandstone member and an 

overlying limestone member, is considered a single 

aquifer because no impermeable bed separates these 

members. In this area the limestone member is about 

100 feet thick and the Glorieta sandstone member is 

about 200 feet thick. The wells at Rehoboth Mission 

and the Navajo housing project and a well northeast of 

the Rehoboth Mission identified as well 3 all partly 

penetrate the San Andres formation (fig. 2).

Glorieta sandstone member. --The color of the Glorieta sandstone member ranges from a very light gray 

to a moderate orange pink. The sandstone is composed 

almost entirely of subrounded to rounded quartz grains 

that are very fine to medium grained and are well 

sorted. The amount of cementation of the sandstone 

varies. Well-cemented zones are intercalated with 

loosely cemented zones. Neither the horizontal nor 

vertical position of these zones within the sandstone 

can be predicted.

Limestone member. --The limestone member is 

grayish orange pink to light brown in color and aphanitic to finely crystalline in grain; it contains varying 

amounts of silt and dolomite near its base. It is thick 

(2 to 4 feet) to very thick bedded (more than 4 feet), 

and has well-developed joint systems and solution 

channels. The upper surface of the limestone was subjected to postdepositional erosion; thus the thickness of 

the limestone is not uniform.

The movement of water within the San Andres formation is controlled by the following factors: The size and 

extent of the joints and solution channels within the 

limestone; the permeability of the underlying sandstone; and the direction of the dip of the beds. Water 

can move freely through the larger open solution channels and joints in the limestone. The permeability of 

the sandstone varies with the size and shape of the connected pore spaces, the grain sorting, and the amount 

of cement deposited in the pore spaces between the 

sand grains. It is possible that well-cemented impermeable zones occur as isolated irregularly shaped 

masses, and that ground water moves downdip around 

them much like water in a stream moves around obstructions. Water tends to move along bedding planes 

and joints but neither are well developed in the sandstone. Consequently the lateral velocity of water within 

the sandstone is comparatively slow because the pore 

spaces are smaller in size than the individual grains. 

The velocity is probably of the magnitude of hundreds 

of feet per year.

Triassic System 

Moenkopi formation

The Moenkopi formation (Ward, 1901) of the Triassic 

system unconformably overlies the San Andres formation, as it was deposited on the eroded surface of the 

Permian rocks. The formation consists of reddishbrown sandy siltstone and claystone, and near the 

Navajo Service Sheep Laboratory it is 34 feet thick.

This formation is not everywhere present; it is absent in some places probably because of nondeposition 

and in others because of postdepositional erosion. The 

area described in this report probably is near the eastern margin of deposition of the Moenkopi formation. 

Wherever present, the siltstone and claystone of the 

Moenkopi formation form a barrier to the upward or 

downward movement of ground water and thereby form 

a part of the confining bed that causes artesian conditions to exist in the San Andres formation.

Shinarump conglomerate

The Shinarump conglomerate (Powell, 1876) overlies 

the Moenkopi formation. Where the Moenkopi formation is absent, the Shinarump lies directly on the limestone member of the San Andres formation. The Shinarump conglomerate consists of irregular lenses of ,conglomeratic sandstone interbedded with grayish-purple 

and light-brown mudstone. At one place, near the Navajo Service Sheep Laboratory, the formation consists 

of 12 feet of mudstone overlain by 13 feet of conglomerate. This is about the average thickness for the formation in this area. The mudstone acts as a barrier 

to the movement of water, and, where it lies directly 

on the limestone member of the San Andres formation, 

it forms a part of the confining beds that cause artesian conditions in that formation. At places, water is 

found in small quantities in the sandstone and conglomerate of the Shinarump conglomerate. The water moves 

downdip to the north. Where the sandstone and conglomerate lie in direct contact with the San Andres 

formation, they could be recharged by water moving 

upward under artesian pressure from that formation.

Chinle formation

The Chinle formation (Gregory, 1916), of Late Triassic age, overlies the Shinarump conglomerate. 

Rocks of the Chinle formation crop out in nearly all 

the Fort Wingate Indian School area. The Chinle formation has a total thickness of about 1, 600 feet in this 

vicinity. The formation consists mostly of claystone 

and siltstone and, in lesser amounts, of sandstone and 

limestone. The outcropping resistant limestone and 

sandstone of the Chinle formation form parallel ridges, 

and the less resistant- claystone and siltstone are exposed in the intervening subsequent valleys. The relatively impervious beds of the Chinle formation are the 

confining layers for all water-bearing rocks beneath 

them.

For the most part, the Chinle formation is not water 

bearing. However, there are three sandstones in the 

Chinle formation in which water has been encountered: 

(1) a lower sandstone at the base of the formation, (2) 

a middle sandstone between 400 and 500 feet above the 

base of the formation, and (3) an upper sandstone between 800 and 850 feet above the base of the formation. 

(See fig. 3.) The lower sandstone is the source of a 

part of the water for the well at the Fort Wingate Indian School. The middle sandstone, which occurs between 400 and 500 feet above the base of the formation, 

is the source of water for a well supplying the trading 

post at Perea (fig. 2). This same sandstone yielded 

water in a well drilled at the lyanbito Day School 

(table 1). Claystone of the Chinle formation confines 

the water in the sandstone and conglomerate of the 

Shinarump conglomerate, and, at any place where
GROUND WATER

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both the Moenkopi formation and the Shinarump conglomerate are missing, the claystone forms the confining bed on top of the San Andres formation.

Geologic Structures 

Folded Rocks

Structurally, the area investigated lies on the nose of 

a broad asymmetric anticline which plunges in a northnorthwest direction. The west limb of the anticline dips 

steeply to the west at angles as high as 85°. The east 

limb of the anticline dips at angles of 5° to 10°. This 

structure, together with the confining beds, controls 

artesian conditions in the aquifers. Artesian pressure 

is present to some degree in all the water-bearing 

rocks in the area. The most striking example is the 

pressure exerted by water in the San Andres formation. 

Wells tapping this aquifer usually flow at the land surface, the rate of flow depending on the altitude at the 

well location and the depth of penetration of the aquifer. 

Open-flow rates as much as a few hundred gallons per 

minute have been measured. One well flowed less than 

1 gpm (gallon per minute) at the land surface, yet the 

hydrostatic pressure causing the flow was sufficient to 

force a column of water to a height of about 180 feet 

above the land surface. Apparently the well bottomed 

in a relatively impermeable part of the aquifer.

Faults

High-angle faults were observed in the vicinity of the 

Navajo Service Sheep Laboratory and the Fort Wingate 

Indian School, and in the mountains to the south. A 

fault just west of the Sheep Laboratory is of the scissor 

type, hinged at the north end, with the maximum displacement to the south. The west side of this fault is 

the upthrown side, with the limestone member of the 

San Andrss formation abutting against rocks of the 

Chinle formation. It is likely that the Santa Fe spring 

(fig. 2) issues along this fault. The fault is covered by 

alluvium in the vicinity of the spring.

GROUND WATER 

San Andres Formation

The San Andres formation is the most reliable aquifer 

in this area. There is a great difference in the amount 

of flow from wells that are situated a few miles from 

each other, ranging from one to several hundred gallons 

per minute. This variation in flow may be due to any of 

several reasons. One of these is the local variation in 

permeability of the San Andres formation. A well that 

penetrates large solution channels, highly jointed rocks, 

or loosely cemented sandstones will yield water more 

rapidly than one that does not intersect these permeable 

zones. Most of the wells in the area investigated do not 

completely penetrate the San Andres formation. Thus 

they do not expose the aquifer completely and so cannot 

take advantage of all the water that would be available.

Recharge Conditions

The recharge area of the San Andres formation extends into the Zuni Mountains for some 10 miles to the

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GROUND WATER OF THE FORT WINGATE INDIAN SCHOOL AREA, N. MEX.

south of the Fort Wingate Indian School. This area is 

updip from the school, where the formation is exposed 

at the surface. Much of the recharge area is forested. 

The recharge occurs by infiltration from precipitation 

or runoff. The average annual precipitation at the 

Fort Wingate Indian School is 14. 45 inches and at the 

McGaffey Ranger Station in the mountains to the south, 

17.26 inches. Because the recharge area lies between 

these two points, the precipitation on the area is considered to be between about 14 and 17 inches per year. 

The amount of water that is available for recharge of 

the aquifer after transpiration, evaporation, and runoff takes place is an unknown quantity. Recharge possibilities should be good, because only a thin soil covers the much-jointed permeable limestone in the 

mountains.

Discharge Conditions

On the basis of measurements made during the summer of 1952, the existing wells in the Fort Wingate 

Indian School area, including those at the Navajo housing project, thV Rehoboth Mission, and the lyanbito 

Day School, discharge from the San Andres formation 

a total of several hundred gallons per minute (.table 1).

Many springs issue from the rocks of the San Andres 

formation in the Zuni Mountains south of the school. 

Most of those observed were discharging from 1 to 5 

gpm. The discharge from these springs flows only 

short distances down the canyons and disappears in the 

alluvium.

Chinle Formation

Three separate sandstone units in the Chinle formation carry water in this area. Beds of siltstone and 

claystone cause the water in the sandstone to be under 

artesian pressure. The Perea well (fig. 3), which 

penetrates the sandstone to about 500 feet above the 

base of the formation, does not flow. The trader at the 

Perea Trading Post reports the well to be capable of 

yielding no more than 10 gpm, which is sufficient only 

to satisfy local requirements for both domestic and 

stock use. The Fort Wingate Indian School well obtained flowing water from the lower sandstones of the 

formation and also from the Glorieta sandstone member. The combined flow from both formations was 45 

gpm. No volumetric test or measurement of flow was 

made while the drilling was confined to the Chinle formation. No data are available as to the total amount 

of water that could be obtained from sandstones of the 

Chinle formation in this area.

Recharge Conditions

The recharge area for the sandstones of the Chinle 

formation is within, and in the vicinity of, the Fort 

Wingate Indian School area. The areal extent of the 

sandstone outcrops is very small and precipitation is 

less than 15 inches per year. Thus, recharge to the 

Chinle formation must necessarily be comparatively 

small. The movement of water within these sandstones 

is downdip in a northerly direction. Because of the extensive and impervious layers of siltstone and claystone interbedded with the sandstone units of the Chinle

formation, probably little or no circulation of water 

takes place between these sandstone units.

Discharge Conditions

Two wells yield water from the Chinle formation in 

the area of this report. The well at the Perea Trading 

Post yields water from the middle sandstone, and the 

well at Fort Wingate School yields some water from 

the lower sandstone. The well at the Perea Trading 

Post is approximately 1 mile downdip from the recharge 

area of the sandstone that it penetrates. If any substantial additional amount of water is to be produced 

from this sandstone, a pumping test should be made to 

determine its hydrologic potentialities. Because of the 

proximity of the well to the recharge area and hence 

the small volume of water in storage, it is probable 

that sustained pumping of large amounts of water might 

cause a large reduction in the quantity stored. The water that was obtained from this same sandstone bed in 

the lyanbito Day School well at a depth between 900 and 

935 feet below the surface was considered unsuitable 

for domestic use (table 2). The water sample was obtained at the' time the well was being drilled. The sandstone was cemented off and drilling was continued into 

the San Andres formation. The lyanbito well is about 

3 miles downdip from the recharge area of this 

sandstone.

The well at the Fort Wingate Indian School is within 

a mile of the outcrop area of the lower sandstone that 

it penetrates, and within one-fourth of a mile of a 

spring that issues from this sandstone.

The springs near the Navajo Service Sheep Laboratory and Fort Wingate Indian School yield a total of 230 

gpm (table 1). These springs are in the area where the 

high-angle faults occur. All the springs discharge water from the basal zone of the Chinle formation. It is 

possible that some of this water is moving upward 

along the fault zones under artesian pressure from 

the San Andres formation. A comparison of chemical 

analyses (table 2) of waters from these springs and 

from the Fort Wingate Indian School well shows these 

waters to be similar; the latter well receives a flow 

from both the Chinle and the San Andres formations.

Hydrologic Character of San Andres Formation

The amount of water that the San Andres formation 

will transmit each day is a function of the hydraulic 

gradient and the transmissibility. On the basis of unpublished information the transmissibility is estimated 

to be less than 25,000 gpd per foot; and possibly, but 

not probably, less than half that figure. The hydraulic 

gradient as determined from existing wells is about 

150 feet per mile. The amount of water in gallons per 

day that will move through each mile-wide section of 

the aquifer, measured at right angles to the hydraulic 

gradient, is calculated as the product of the coefficient 

of transmissibility and the hydraulic gradient.

Therefore, something less than 3, 750, 000 gallons of 

water per day, or 2, 600 gpm, moves through each 

mile-wide segment of the aquifer. Assuming a 1, 000- 

foot spacing of wells along the strike of the beds, the 

5 wells drilled in a mile-wide zone could each safely
CONCLUSIONS

yield an amount less than 400 gpm, depending on the 

true value of the coefficient of transmissibility.

Future Development

New wells developed in this area should be carefully 

planned and systematically carried out. Sites for them 

should be carefully chosen as to direction and distance 

from existing wells. The suggested figure of 1, 000 

feet for the spacing of wells is arbitrary, but it seems 

as reasonable as any figure that can be given until additional data have been obtained. After the completion 

of each new well, an extensive pumping test should be 

made to help in obtaining a more reliable value for the 

coefficient of transmissibility.

Well sites should be located perpendicular to the 

direction of dip of the strata, and hence perpendicqlar 

to the direction of movement of water within the aquifer. A well drilled updip and near an existing well 

might interfere with the movement of water toward the 

existing well, and thereby lessen its production. A 

well drilled downdip from an existing well might not 

receive all the water that could otherwise be available 

to it, as the existing well would intercept some of the 

water.

At the present time nearly all water obtained from 

wells in the San Andres formation is by natural flow. 

If only the natural flow is used, additional wells probably can be spaced more closely than if the wells are 

to be pumped, as their average yield would be less 

than the amount that could be pumped. If increased 

water requirements necessitated pumping the wells, 

then the cone of pressure relief surrounding each well 

would be greater, the well would draw water from a 

greater horizontal distance, and the spacing between 

wells would have to be greater. Wide spacing would 

prevent the cones of pressure relief of the individual 

wells from seriously overlapping and causing a decrease in production.

QUALITY OF WATER

Water from the middle sandstone of the Chinle formation shows an increase in dissolved solids in a 

downdip direction from the recharge area. This is 

manifested by the increase in dissolved solids between 

the Perea well and the lyanbito School well (table 2). 

The water from the lyanbito School well, which was 

subsequently cemented off, had the highest observed 

concentration of dissolved solids and the greatest concentration of bicarbonate, chloride, and fluoride. Waters from the Santa Fe, Navajo Sheep Laboratory, and 

Fort Wingate Indian School springs all issue from the 

basal part of the Chinle formation. These waters are 

hard and contain mostly calcium, bicarbonate, and 

sulfate, and small amounts of sodium and chloride. 

The water from the Perea well contains the largest 

amount of sodium and sulfate of any of the waters sampled. This well obtains water from the middle sandstone of the Chinle formation. Because of the high percentage of sodium and the high dissolved solids, this 

water is considered undesirable for domestic, industrial, or irrigation use.

The dissolved-solids concentration of the waters 

yielded by the San Andres and Chinle formations in this

area has a rather wide range (table 2). Water from 

most of the wells that penetrate the San Andres formation is very hard and contains mostly calcium, magnesium, and sulfate, and minor amounts of chloride. 

Water from some of the wells contains perceptible 

amounts of hydrogen sulfide gas. The water is utilized 

as a public supply, and for cooling and other purposes 

after treatment. The hardness of the water in the San 

Andres formation may be explained as being the result 

of solution of the limestone member and removal of 

calcium carbonate cement from the sandstone member 

as ground water moves through the formation. Large 

amounts of sulfate in this water indicate the presence 

of gypsum in the formation, but no beds of gypsum 

were observed in the top 200 feet of the formation. 

Gypsum may be disseminated throughout the formation, however.

Water from the Rehoboth well, which is reported to 

tap the San Andres formation, is only moderately hard 

and contains considerable sodium and chloride. The 

rather high concentration of sodium and chloride in 

this water may be the result of a mixing of waters from 

the Chinle and the San Andres formations.

CONCLUSIONS

Two formations in the Fort Wingate Indian School 

area yield water to wells, the Chinle formation and the 

San Andres formation. The sandstones in the Chinle 

formation are recharged locally, and the recharge 

area is narrow. Therefore, only a limited amount of 

water may be available to wells drilled into the sandstones of the Chinle. For the most part, water from 

the middle sandstone of the Chinle formation is undesirable for domestic uses. However, water from the 

Perea well is used. Water from the lower sandstone 

unit of the Chinle formation is suitable for domestic 

and irrigation use in the vicinity of the school.

Flows of water from several wells that penetrate the 

San Andres formation are listed in table 1. The total 

of these flows shows that the annual discharge from the 

aquifer in this area is not less than about 750 acrefeet. In addition, about 380 acre-feet of water per 

year is discharged from the Chinle formation, much 

of it perhaps indirectly from the San Andres formation. 

Precise data for average annual recharge to the aquifers are unavailable.

The San Andres formation is potentially the most 

productive aquifer in the area. The recharge area for 

this aquifer is rather extensive and is located at a 

higher altitude and in an area of greater precipitation 

than the area occupied by the school. Structural and 

lithologic conditions are favorable for the accumulation of water in the aquifer under hydrostatic pressure. 

The fine-grained rocks of the Chinle formation form 

most of the overlying confining beds. Wells tapping 

the San Andres formation produce as much as a few 

hundred gallons of water per minute. Higher rates of 

withdrawal are considered feasible, up to the limit of 

the aquifer to transmit water, but no exact limiting 

figure can yet be stated.

Full penetration of the aquifer is an important factor 

governing well productivity. It is probable that existing 

wells would have larger yields if they completely penetrated the aquifer. Proper spacing of wells as to dis-
8 GROUND WATER OF THE FORT WINGATE INDIAN SCHOOL AREA, N. MEX.

tance and direction from one another, proper setting 

and perforating of casing, and proper development following drilling are considered to be highly desirable 

in future wells. These would give better wells for less 

overall cost. On the basis of the field data collected, 

spacing flowing wells 1, 000 feet apart along the strike 

of the formation is not likely to cause serious overdevelopment of the aquifer. Future development plans 

should take into account the hazard of overproduction 

from the San Andres formation. Overproduction would 

progressively lower the artesian pressure, causing 

the flow of water from wells to diminish and ultimately 

to cease. This eventuality is not anticipated as a result of production at the present rate.

LITERATURE CITED

Gregory, H. E., 1916, The Navajo country: U. S.

Geol. Survey Water-Supply Paper 380. 

Lee, W. T., and Girty, G. H., 1909, The Manzano

group of the Rio Grande valley, New Mexico: U. S.

Geol. Survey Bull. 389. 

McKee, E. D., and Weir, C. W., 1953, Terminology

for stratification and cross-stratification in sedimentary rocks: Geol. Soc. America Bull., v. 64,

no. 4, p. 361-369. 

Powell, J. W., 1876, Geology of eastern portion of

Uinta Mountains: U. S. Geol. and Geog. Survey

Terr., 2ddiv., p. 53, 68-69. 

Ward, L. F., 1901, Geology of the Little Colorado

Valley: Am. Jour. Sci., 4th ser. , v. 12, p. 401-

413.

Table 1. --Well and spring discharge, depth of wells, and aquifers in the Fort Wingate Indian School area

Well or spring

16B- 12.......... .............................................

16B-40. ......................................................

lyanbito Day School well................................

Well 3........................................................

Rehoboth Mission well................. .................

Wingate railroad station well.... .....................

Fort Wingate Indian School well......................

Navajo Service Sheep Laboratory spring... .......

Santa Fe spring.................................. .........

lyanbito Day School well^....... .......................

Flow 

(gpm)

8.0

70.5

4.0

1

10

60

45

180

33.4

19.2

Total depth 

(feet)

1,675

1,510

1,950

1,569

1,305

348

490

1,510

Aquifer

San Andres formation.

Do.

Do.

Do.

Do.

Do.

Chinle and San Andres

formations. 

Do.

Do.

Do.

Chinle formation.

Do.

*Water sample obtained from sandstone in Chinle formation, 900 to 935 feet below surface, when the well was 

being drilled.
Table 2. Analyses of water from wells and springs in the Fort Wingate Indian School area a

[Analyses by Geological Survey. Parts per million except specific conductance, temperature, and 

Well or spring

16B-12. ..................

16B-40... ................

lyanbito Day School

u/011

Rehoboth Mission

well....................

Fort Wingate Indian

Fort Wingate Spring.

Navajo Service Sheep

Laboratory spring.

Perea well..............

lyanbito Day School

we 11*

Date of

collection

5- 3-50

5- 9-50

2-27-52

6-12-52

12-10-53

8- 9-50

8- 9-50

8- 4-50

8- 4-50

3-31-51

Temperature

(°F)

67

85

81

60

54

56

55

Specific

conductance

(micro -

mhos at

25° C)

1,350

1,340

1, 170

1.510

1,010

913

703

730

3,030

3,780

Silica

(Si02 )

11

13

13

13

13

8.9

9.5

Calcium

(Ca)

169

116

29

160

141

103

8.0

Magnesium

(Mg)

87

61

12

45

40

33

3.7

Sodium

and potassium

(Na+K)

24

112

306

9.2

7.6

5.8

684

Bicarbonate

<HC03)

247

218

219

284

260

276

328

325

350

488

Sulfate

(S04)

596

571

463

365

283

118

625

Chloride

(Cl)

5

7

6

50

7

8

8

7

412

443

Fluoride

(F)

0.2

. 1

.4

.6

.2

.2

.1

.5

2.2

N

(

1 Water sample obtained from sandstone from Chinle formation, 900 to 935 feet below surface, when well was being d
10 GROUND WATER OF THE FORT WINGATE INDIAN SCHOOL AREA, N. MEX. 

Stratigraphic section, Permian and Triassic. Fort Wingate Indian School area

[Measured by R. L. Jackson and S. R. Johnson November 1950. The descriptive terminology used in this stratigraphic section is generally similar to that proposed by McKee and Weir (1953) in a paper on descriptive terms 

applied to stratification in sedimentary rocks]

Feet 

Triassic:

Wingate sandstone (Undescribed, not present along line of geologic cross section)............................... 355

Unconformity:

Chinle formation: 

"B" member:

36. Mudstone, variegated grayish-red and light-greenish-gray, banded; composed of silt and clay;

poorly cemented; flat,irregularly bedde^J; forms a slope. Base is irregular.......................... 8

35. Limestone, pale-reddish-purple; silty; contains some medium-crystalline calcite; flat,irregularly bedded; weathers hackly; forms a ledge slope.............................................................. 10

34. Limestone, mottled very light gray and pale-reddish-purple; medium crystalline with rare

rounded quartz grains; flat thin,irregularly bedded; weathers hackly; forms an irregular ledge. 6 

33. Limestone, light-brownish-gray; finely crystalline; flat,irregularly bedded; forms a prominent

ledge. Base is irregular.............................................................................................. 6

32. Mudstone, same as unit 26............................................................................................... 9

31. Limestone, mottled pale-reddish-purple and light-gray; aphanitic; flat, irregularly bedded;

weathers knobby; forms a weak le.dge. Base is flat........................................................... _2

Total "B" member.................................................................................................... 41

"C" member:

30. Mudstone, same as unit 26............................................................................................... 440

29. Limestone, sandy, same as unit 27................................................................................... 2

28. Mudstone, same as unit 26............................................................................................... 38

27. Limestone, sandy, pale-red-purple; silty and finely crystalline; flat-bedded; weathers blocky;

forms an irregular ledge. Base is flat............................................................................ 2

26. Mudstone, mottled dark-reddish-brown and light-greenish-gray; very thick gnarly bedded;

weathers hackly; forms an irregular slope. Base is flat................................................... 11

25. Sandstone, grayish-red-purple, very fine grained, poorly sorted; composed of subangular

stained quartz with rare mica, rare black accessory minerals, and rare argillaceous material; firmly cemented, weakly calcareous; trough crossbedding, low-angle, medium-scale 

crossbeds; weathers blocky; forms a weak ledge. Base is flat............................................ 10

24. Covered interval............................................................................................................ 45

23. Sandstone, light-olive-gray, fine to very fine grained, fair-sorted; composed of subrounded to 

subangular frosted quartz with abundant black accessory minerals, common argillaceous material and rare red accessory minerals; firmly cemented, weakly calcareous; trough crossbedding, low-angle medium-scale crossbeds; weathers blocky; forms an irregular slope. 

Beds contain siltstone and claystone granules at base. Unit becomes more calcareous towards the top. Base is gradational................................................................................. 20

22. Siltstone conglomerate:

Matrix, light-greenish-gray, medium- to fine-grained, poorly sorted; composed of subangular frosted quartz with common black and red accessory minerals and argillaceous material; firmly cemented, calcareous; 

Gravel, angular to subangular siltstone and claystone pebbles (1/8 to 1/2 in. across),

reddish-brown to dark-reddish-brown; flat, irregularly bedded; weathers rounded and pitted.

Base is gradational................................................................................................... 2

21. Claystone, forms a niche................................................................................................. 1

20. Claystone, same as unit 18.............................................................................................. 54

19. Mudstone, grayish-red; composed of amber and white quartz with common mica and rare green 

accessory minerals; poorly cemented; flat,very thin bedded; weathers smooth; forms a slope. 

Base is irregular........................................................................................................ 1

18. Claystone, mottled grayish-red-purple and light-greenish-gray; very thin,irregularly bedded; 

weathers hackly; forms an irregular slope. Contains rare very fine grained quartz inclusions. Base is gradational............................................................................................ 54

17. Mudstone, mottled grayish-red-purple and light-greenish-gray; composed of silt and clay;

crossbedded, low-angle small-scale crossbeds; weathers hackly; forms an irregular slope.

Base is gradational..................................................................................................... 18
GROUND WATER OF THE FORT WINGATE INDIAN SCHOOL AREA. N. MEX. 11 

Stratigraphic section, Permian and Triassic, Fort Wingate Indian School area--Continued 

Unconformity--Continued Feet

Chinle formation--Continued 

"C" member Continued 

16. Conglomerate:

Matrix, sandstone, light-greenish-gray, fine-graine4 poorly sorted; composed of subangular 

amber, white, and clear quartz with rare black accessory minerals and abundant argillaceous 

material; poorly cemented, weakly calcareous; very thick bedded; weathers gnarly; forms 

an irregular slope. Base is irregular. 

Pebbles, siltstone, limestone and quartz pebbles {1/8 to 1 in. across), angular to subangular;

siltstone and limestone pebbles predominate................................................................. 5

15. Claystone, mottled moderate-reddish-brown and light-greenish-gray; very thin, irregularly 

bedded; weathers hackly; forms an irregular slope. Contains common subangular quartz 

granule inclusions. Base is irregular and gradational....................................................... 19

14. Claystone, variegated grayish-red-purple and greenish-gray; very thin,irregularly bedded;

weathers hackly; forms an irregular slope. Base is irregular............................................ 30

13. Sandstone, calcareous, variegated pale-reddish-purple and light-greenish-gray, very fine 

grained, poorly sorted; composed of subangular to angular white and amber quartz grains 

with common black detrital and argillaceous material; firmly cemented, highly calcareous; 

flat, irregularly bedded; weathers blocky; forms a weak ledge. Base is irregular................. 25

12. Claystone, grayish-red-purple; irregularly bedded; weathers hackly; forms an irregular slope.

Base is concealed....................................................................................................... 6

11. Covered....................................................................................................................... 8

10. Sandstone, pale-red-purple (weathering light brown),fine to very fine grained, poorly sorted; 

composed of subangular amber, clear and smoky quartz with abundant black accessory minerals, rare green accessory minerals and common argillaceous material; well-cemented, 

noncalcareous; flat,thin,irregularly bedded; weathers blocky; forms an irregular ledge. 

Base is gradational..................................................................................................... 6

9. Mudstone, grayish-red-purple; composed of silt and clay with common mica accessories,

highly argillaceous; firmly cemented; very thin, irregularly bedded; weathers hackly; forms

a ledge-slope. Base is irregular.................................................................................. 18

8. Sandstone, grayish-orange-pink, fine-grained, well-sorted; composed of rounded to subrounded 

clear and frosted quartz with rare green accessory minerals and argillaceous material; 

trough crossbedding; low-angle medium to large-scale crossbeds; weathers blocky; forms a 

vertical cliff. Granules of quartz occur along base of crossbeds. Base is irregular.............. 29

7. Limestone, pale-olive, medium-crystalline; thin (| to 1 in.), flat-bedded; weathers blocky;

forms a blocky ledge. Base is flat................................................................................ 18

6. Sandstone, argillaceous, pinkish-gray, very fine to coarse-grained, poorly sorted; composed 

of subangular to angular clear and frosted quartz grains with abundant argillaceous material; poorly cemented; very thick bedded; weathers smooth to rounded; forms a weak ledge. 

Contains abundant quartz granules. Conglomerate at base (basal 2 ft) contains quartz pebbles (^ to 1 in. across) which grade upward into argillaceous sandstone. Base is gradational.. 11 

5. Claystone, dusky red-purple and light-*ray; very thick bedded; weathers hackly, forms a

rolling steep slope. Grades upward into unit 6. Base is sharp........................................... 98

4. Mudstone, mottled grayish-green and pale-reddish-purple; composed of silt and clay; very thin, 

irregularly bedded; forms a rolling steep slope. Contains pale-greenish-gray siltstone ledgeforming units: a lj-ft ledge at the base, and a 1-ft ledge 15 ft above the base. Base is sharp 

and flat..................................................................................................................... 31

3. Claystone, mottled grayish-yellow-green and dark-reddish-brown, very thin,flat,irregularly

bedded; weathers hackly; forms a steep slope. Base is flat............................................... 89

2. Siltstone, argillaceous, yellowish-gray, poorly sorted; composed of subangular quartz with 

rare red accessory minerals, common black accessory minerals, and common to abundant 

argillaceous material; very flat; thin, irregularly bedded; forms a weak ledge. Base is 

concealed.................................................................................................................. 3

1. Covered, irregular, flat slope......................................................................................... 70

Total "C" member.................................................................................................. 1, 164

"D" member:

12. Sandstone, grayish-orange-pink (weathers light brown), very fine grained, fair-sorted; composed of subrounded clear quartz with common black accesspry minerals; firmly cemented, 

siliceous; trough crossbedding, high-angle medium-scale crossbeds; weathers smooth to 

rounded; forms a rounded ledge. Base is irregular.......................................................... 33
12 GROUND WATER OF THE FORT WINGATE INDIAN SCHOOL AREA, N. MEX.

Stratigraphic section, Permian and Triassic, Fort Wingate Indian School area Continued

Feet 

Unconformity--Continued

Chinle formation--Continued 

"D" member Continued 

11. Conglomerate:

Matri^ grayish-red-purple, medium to very fine grained, poorly sorted; composed of subangular clear and frosted quartz with common black accessory minerals. 

Gravel, pale-olive-gray to reddish-brown; limestone and siltstone pebbles (£ to 1 in.), 

subangular and pitted; very thick bedded; weathers knobby; forms an irregular ledge. 

Base is irregular..................................................................................................... 7

10. Claystone, dark-reddish-brown; very thin flat bedded; weathers hackly; forms a rolling slope.

Base is gradational...................................................................................................... 35

9. Claystone, reddish-brown-purple; flat,very thin bedded; weathers hackly; forms a rolling

slope. Base is concealed.............................................................................................. 41

8. Covered, long low irregular slope..................................................................................... 83

Total "D" member.................................................................................................... 199

*;

Shinarump conglomerate: 

7. Conglomerate:

Matri^ very pale orange (weathers dark reddish brown), very coarse to very fine grained, 

poorly sorted; composed of subangular clear, frosted, and stained quartz with rare red 

accessory minerals and feldspar detritals; firmly cemented. 

Gravel, quartz, jasper, chalcedony and feldspar pebbles, subangular (i to 2? in. across),

very thick irregularly bedded. Base is irregular........................................................... 13

6. Mudstone, mottled grayish-purple and light-brown; composed of claystone and siltstone; firmly 

cemented; very thick, irregularly bedded; weathers hackly; forms a ledge slope. Base is 

irregular................................................................................................................... 12

Total Shinarump conglomerate.................................................................................... 25

Moenkopi formation:

5. Sandstone, yellowish-gray (weathers reddish brown), very fine grained, poorly sorted; composed of subrounded to subangular clear quartz grains with rare red accessory minerals, 

common black accessory minerals and abundant argillaceous material; firmly cemented, 

planar crossbedding, low-angle small-scale crossbeds; weathers smooth to rounded; forms a 

weak ledge. Base is,sharp and irregular......................................................................... 27

4. Claystone, dark-reddish-brown; very flal^ thin bedded; weathers hackly; forms an irregular

slope. Base is irregular.............................................................................................. 5

Total Moenkopi formation.......................................................................................... 32

Permian:

San Andres formation: 

Limestone member:

3. Limestone, grayish-orange-pink (weathering gray), finely crystalline; thick to very thick bedded; 

weathers pitted; forms a vertical cliff. Manganese detritals are common. Rare molluscoid 

fauna, preservation poor. Jointing well developed. Base is flat.......................................... 86

2. Dolomitic limestone, silty, light-brown, aphanitic; composed of dolomite and silt; very thick 

bedded; weathers blocky; forms a vertical irregular cliff. Contains rare calcite geodeS (j in. 

across). Base is irregular............................................................................................ 11

Total limestone member............................................................................................ 97

Glorieta sandstone member (Incomplete):

1. Sandstone, moderate orange-pink (weathering moderate brown), very fine grained, poorly

sorted; composed of rounded to subrounded clear quartz with rare black accessory minerals; 

well cemented, siliceous; thin to thick bedded; weathers blocky; forms a vertical cliff. Base 

is concealed................................................................................................................ 100

IMT.-DUP. SEC., HASH.. 0.0.71,2)7