The geology of the northern part of the Huachuca Mountains, Arizona

Item Type text; Dissertation-Reproduction (electronic)

Authors Alexis, Carl Odman, 1918-

Publisher The University of Arizona.

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Link to Item http://hdl.handle.net/10150/565345 THE GEOLOGY OF THE NORTHERN PART OF THE

HUACHUCA MOUNTAINS, ARIZONA

Carl 0. Alexis •i

A Thesis

submitted to the faculty of the

Department of Geology

in partial fulfillment of the requirements for the degree of

Doctor of Philosophy

in the Graduate College, University of Arizona

1949

Approveds Director of Thesis D a ^ SIT TO THAT TATnTAOT TUT TO YO'XIO-TD TAT

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CONTENTS

ZagS In'broduction ...... ,.,... . .,..,..., .. ,, ... 1 Location . ... 1 Culture ...... 1 Transportation...... 2 Drainage ... 2

Topography ...... 3

Flora ...... 3

F a u n a ...... 4

Previous investigations ...... 4

Purpose and scope of the examination ., ... 4

Field work ...... 5

Acknowledgments ...... 5

Stratigraphy ...... 6

Pre-Cambrian rocks ...... 7

Cambrian sedimentary rooks ...... • •• 7

Bolsa quartzite ...... 7

Cochise formation ...... 9

Abrigo formation •...... ,......

Devonian sedimentary rocks ...... 11

Mis sis sippian sedimentary rocks ...... 12

Pennsylvanian sedimentary rocks ...... 13

Permian sedimentary rocks . . . 1 3

Lower Cretaceous rocks ...... ,...16

Parker Canyon section ...... 16

2 0 3 2 4 % Stratigraphy (contd) Page

Limestone conglomerate formation ...... 17

Lower elastic f ormation...... 20

Limestone formation ...... 23

Upper elastic formation ...... 25

Correlation of the Cretaceous section ...... 26

Distribution of Lower Cretaceous volcanic rocks 28

Tertiary rocks ...... 29

Tertiary volcanic rocks ...... 29

Gila conglomerate ...... 30

Quaternary rocks ••••••••••••••«•••••••••••«••• 32

Igneous racks 33

Pre-Cambrian granite ......

Lower Cretaceous volcanic racks . 35

Parker Canyon section ...... 35

Volcanic flow in Blackt&il Canyon ...... 37

Tertiary volcanic racks ...... 38

Post-Cretaceous intrusive racks .... . 39

Geologic structure ...... 41

Structure elements ...... 41

Folds ...... «••«•••••• . 41

Rough Canyon anticline ...... 41

Rough Canyon syncline ...... 41

Drag folding ...... 42

Folding of the Tertiary rocks , 43 .Page

Faults ...... 44

Huachuca Canyon fault 44

Crest Line thrust fault ...... 45

Basin Range fault ...... 47

Lyle Peak fault 48

Lone Mountain fault structure 49

Structural history 50

Pre-Laraaide structures ...... 50

Post-Permian Pre-Cretaceous, structure .... 50

Cretaceous structures ...... 52

Laraad.de folding 53

Post-Laramida structures ...... ••••.« 54

Physiographic history 56

Ore deposits 63

Water supply ...... 67

Bibliography ...... 72 ILLUSTRATIONS

PLATES

1. Geologic map of the northern part of the Huachuea Mountaiae, Arizona ...... In pocket

2. Geologic structure sections of the northern : part of the Huachuea Mountains along lines shown on Plate 1 ...... In pocket

3. Index map (Arizona, New Mexico and northern Mexico., In pocket

4. Map of Benson and Hereford Quadrangles, Arizona (showing elevation of water table) In pocket

5# Generalized columnar section Huachuea Mountains, Arizona ...... In pocket

6. Stream piracy northern end of the Huachuea : Mountains ...... In pocket

(following page 74) ;

7. A. Bobocomarl Valley B. Northern end Huachuea Mountains

8. A. Summer thunderstorm over Huachuea Mountains. B. Summer thunderstorm over Mustang Mountains.

9. A. Southwest flank Huachuea Peak B. Northwest flank" Huachuea Peak

10. A. South side Garden Canyon B. South side Huachuea Peak lie ki Cambrian Bolsa quartzite B. Cambrian Bolsa quartzite

12. A. Mississippiah Escabrosa limestone faulted over Cambrian Abrigo formation B. Cambrian Abrigo formation

13. A. Permian limestones on Lyle Peak B. Permian, limestones in Garden Canyon

14. A. Lower Cretaceous limestone conglomerate formation B. Transverse section of Araucarioxdvlon sp. ILLUSTRATIONS

Plates

15. A, Radial section of Arancarioxvlon sp. B, Tangential section of Arancarloxylon sp.

16. A, Oyster bed in Lower Cretaceous limestone formation B, Same as above

17. A, Ostrea ragsdalei B, Glauconia branneri

18. A, Northwest nose of the Rough Canyon anticline B, Same as above

19. A, Lower Cretaceous lower clastic formation near head to Huachuca Canyon B, Lower Cretaceous upper clastic formation in Parker Canyon

20. A, Lower Cretaceous strata near head of Algerita Canyon B, Same as above

21. A, Tuffs and sandstones in Tertiary volcanic rocks B, Closer view of above

22. A, Tuffs and sandstones in Tertiary volcanic rocks B, Tertiary rhyolite porphyry flow ;

23. A, Pliocene Gila conglomerate B, Pliocene Gila conglomerate "

24. A, B, Boulder of conglomerate in Pliocene Gila conglomerate

25. A, Fine grained equivalent of Pliocene Gila conglomerate B, Same as above.

26. A, Crest Line thrust fault in Garden Canyon B, Same as above.

27. A, Crest line thrust fault on Huachuca Peak B, Same as above

28. A Basin Range fault B Basin Range fault ILLUSTRATIONS

Plates

Sags

29* A, Basin Range fault • ' >.o B. Basin Range fault

Figures

!• . Geologic occurrence of springs in the Manila Mine Area...*, 70

2* Geologic occurrence of springs.in the Huachuca Mountains •• 71 •1<

INTRODUCTION

: v.'r Location L '

The Huachuca Mountains are in southeastern Arizona, where they fora

a northwest trending range about twenty miles long. The range lies in

the southwest corner of Cochise County. The Huachucas extend from Lat.

31° 20* N 0# Long. 110° 16* W. ( a point on the Mexican border) to Lat.

31° 36' N., Long. 110° 27' if.

The area mapped is about 10 miles square. It extends one to two

miles out from the base of the range on the north and east. The south­

ern boundary is Garden Canyon, which flows eastward, and Copper Glance

Canyon, which flows westward. The area extends two miles west of Cochise

County into Santa Cruz County. All of Township R* 19 E,, T. 22 S., and

parts of Townships R. 19 £., T. 21 S.j R. 19 £., T. 23 S.j R, 18 E.,

T. 21 S.j R. 18 E., T. 22 S.j R. 18 E., T. 23 S.j R. 20 E., T. 21 S.,

and R. 20 E., T. 22 S. are in the area, making a total of approximately

100 square miles.

Culture:

Ranching and mining are the principal activities in the Huachuca

Mountains. Until 1947 the northern portion of the range was part of the

Fort Huachuca Military Reservation, which during World War II had a com­

plement of fifteen to twenty thousand' men. ' ■' ^ Transportation ’-r - v - ;•,

- -v^ ' ” ■ v; ' .• , : ' W ' ' - . : - "" The Douglas-Tucson line of the Southern Pacific Railroad runs up

the San Pedro River Valley, Fort Huachuca is connected with it at Lewis

Spring by a spur line fourteen miles long, A paved highway connects

Fort Huachuca with Tombstone, Bisbee, and Tucson. This road runs parallel

to the eastern front of the Huachuca Mountains. The northern, western,

and southern flanks of the range are served by graded roads, A road

passable by a small truck or jeep runs through the range up Garden Canyon and down through Scotia and Copper Glance Canyons. z::y:.r \ " / -y: ■ y-., yy -y ;"y y-. ‘

v i-yy Drainage y,- ;

The east flank of the Huachuca Mountains is drained by streams flowing eastward into the San Pedro River, which lies about ten miles

from the base of the range. The San Pedro flows northward and north­ westward to the vicinity of Winkelman, Arizona, where it empties into the Gila River,

On the west flank of the Huachucas the drainage goes into two

separate basins. The one to the north is formed by the Huachucas on

the east and the Canelo Hills to the west and south. The Bobocomari

River and its tributaries in Sycamore Gulch (Lyle Canyon) and O'Donnell

Canyon, drain this area, carrying the flow northward and eastward into

the San Pedro River,

The southern basin is bounded on the northeast and east by the

Canelo Hills and the southwestern flanks of the Huachuca Mountains, on

the north by the hilly volcanic area lying between the Canelo.Hills.and -3-

the Patagonia Mountains, and on the west by the Patagonia Mountains.

This basin is drained by the Santa Cruz River, which flows southward

into Mexico, then west and north, re-entering the United States near to too.- 15 3t. i v.-" 5.1 US, Nogales, and farther north, passing through Tucson. ov;-:y, It; oot-tu OX: ;;o:;r-c xl ihx flol't tno rol L '• loo' t-:.-.:,-'.-0 ' - Topography limvr roocxotoo.

.. : •• .a .'aa : x vlAa. a■ :,a : ; . a . The Huachuca Mountains rise abruptly from the gently sloping 5 ^ - a r t pui oog o t M.-t ta.atala V-'.-d" C - 'tax taaot pediment surrounding them# The break between the pediment and the hy .-ra'.vat:::'* v -ta I'-n '-tl/' r-t;poett;;a range is at an elevation of about 5100 feet on the eastern and northern

flanks and near 5500 feet oh the western flank. From these elevations

the peaks in the northern.part of the range rise to 8400 feet. The peaks

in the southern part of the range are somewhat higher* X U yuOu-'X ..x'l ;u:: u/ .'uu :.".u:' ■ ?.>/ 5':x:: X. 5' xx,;,. ' -IXy :■ xv Canyons on the east flank of the range have been cut back two-thirds the '::x V; 3 . "h. T XX-1'G: ■ ulx X ••’"'X'XX^ ":V; / . X ,X'. lu XXX.;.,: of its width# The principal ones are Huachuca Canyon (Post Canyon) and v; . C/'x x x n x x x : -xx- ;;.xx ;hx 5xxlxx:x X: ux.X.lxx, Yh’ r.yxxr ' XX X-. Garden Canyon (Tanner Canyon)* The pass at the head of Garden Canyon is O'/'1 u-u-uX • IxxX'Xu V-X';xx:- :: XX': hx'-,'X,~ ^X.CXpV ..Xr X-'- T'.TXuVx XX X‘ -.UX''.u at an elevation of 6550 feet, 7X,xx;.- ; x: x : .uxox ox' thx orxux;; 'Ix-x - Ixxxl, - xx .x. xxo 5- ■,» xuu^xjx xx x

-xxX, . Flora

The flora of the Huachucas; represents three zones> controlled by the

amount of annual precipitation in each# Since the amount of annual preci- X : , X ; XX: ...u; ul .XYx: - X ;-:-:.-:,:;.;'.:.1 :-x xxx-::'X l:,;;. uX pitation increases with elevation, these zones appear at definite altitudes*

In the order of increasing elevation they are: the grasslands zone,-the oak

woodland zone, and the conifer forest zone# ; A detailed description of these

zones is given hy Darrow*^ ' x :.,xx Uxx : l :'7x 1: x:.x.

1# Darrow, R.A«, Arizona range resources and their utilization, I, Cochise Countys Univ. of Ariz., Coll, of Agri., Tech. Bull. 103, 1944. Fauna

Because the Fort Huachuca Military Reservation has been "out of bounds8 to hunters from 1881 to the present time, the natural wild life has been preserved in this area. During the course of the field work the following animals were observed: deer, mountain lion, coati, peccaries, squirrels, rabbits, gila monster, and snakes.

Detailed descriptions of the mammals and birds of the area are 2 3 given by Cahalane and by Swarth respectively.

Previous Investigations

- The Huachuca Mountains were mapped on a reconnaissance basis for the geological map of Arizona by Dr. Carl E. Lausen. This map shows the areal distribution of the pre-Cambrian granite, the Paleozoic rocks, the Cretaceous rooks, and the Tertiary volcanics. No reports or records of previous investigations are known, except for the reports on ground water in the offices of the Ground Water Division of the D. S. Geological

Survey in Tucson, Arizona.

Purpose and Scope of the Examination

This report is the result of a field investigation undertaken in : ' : - • ' - ...... : - 23*

2. Cahalane, V.H., Mammals of the Chiricahua Mountains, Cochise County, Arizona: Jour, of Mamaology, Vol. 20, pp. 418-439, November, 1939.

3. Swarth, H. S., Birds of the Huachuca Mountains: Pacific Coast Avifauna No. 4, Cooper Ornithological Club of California. partial fulfillment of the> requirements for an advanced degree at the

University of Arizona# Its main purpose was to determine the structure of the Huachuca Mountains# v ,

The stratigraphic study of the Paleozoic formations was confined to identification of the formations present in order to show their boundaries

/ on the geologic map. The Cretaceous strata were studied in greater detail because they are unusually thick for this part of Arizona, and because they are not as well known as the Paleozoic strata#

... " " ' ' Field Work ^ " ' ' '

Field work during the summer of 1947 was confined to an area north of Huachuca Canyon and east of the crest of the range* This area did not include all of the features critical in working out the problem, there­ fore, during the winter and spring months of 1947-48 the study was extend­ ed south to Garden Canyon and west to the southern part of the Canelo

Hills# The last field work done was in February and March, 1949.

Acknowledgments

.... Many people aided the writer in preparing this report* Officials of the U# S« Army, War Assets Administration, the University of Arizona, the U# S# Forest Service, and the U# S. Geological Survey, Ground Water

Division, performed various services for the writer which made this

investigation.possible* Permission to work in the area, maps, and

reports were obtained from these sources# . Menbere of the Department of Geology and Mineralogy at the

University of Arizona, both faculty and graduate students, were freely consulted during the preparation of this report, and all gave material assistance* Dr* E, Sw Butler, Dri A« A. Stoyanow, Dr* E, D*

Wilson of the Arizona State Bureau of Mines* and Professor E* D. McKee accompanied the writer into the field on various occasions» Dr, /

Short arai Mr* C.J* Peng, graduate student in mineralogy, aided in the thin section studies of the igneous rocks*

Appreciation is expressed to Mr* Robert Weber and Mr* Donald

Blackjj both graduate students in geology, for information and photo­ graphs supplied by them. - : • - ' ' ; ' : '

Residents of the area were all hospitable and generous in giving information which materially speeded up the field work®

^ - STRATIGRAPHY

Paleozoic, Mesozoic, and Cenozoie strata are exposed in the northern part of the Huachuca Mountains* Paleozoic formations are correlated with corresponding rock units present elsewhere in south­ eastern Arizona, but they are so strongly faulted and folded that only rotigh approximations of their thicknesses can be obtained* Until an accurate, large-scale topographic map is available on which to show ' - details of structure affecting the Paleozoic rocks, these stratigraphic units can not be measured* In the Whetstone5 Mountains, which'lie to the north of the Huachucae, Paleozoic formations are much less disturbed*

The section there closely resembles in character that in the Huachucas and appears to b® of the- same approximate thickness* : - .

The Mesozoic era la represented in the Huachucae by rocks of Lower

Cretaceous age# : The principal section of these strata Is well exposed1 on the western slope of the mountains and Is relatively undisturbed by faulting# Cenosoic beds are of two types: (l) volcanic flows and agglo­ merates, and (2) later, semi-consolidated conglomerates and gravels which are tentatively correlate! with the Gila conglomerate# -.

Pre-Cambrian Rocks

There are no .pre-Cambrian sediments exposed in the northern part of the Huachuea Mountains# In other areas of southeastern Arizona, as in the tihetstone Mountains, the Mule Mountains, and the Tombstone Hills, the Pinal schist constitutes a part of the pre-Cambrian complex# This 4 schist was probably formed by the mmtamorphism of sedimentary rocks ,

The . pre-Cambrian age is represented in the Huachucas by a coarse­ grained granite, almost pegmatitic in character# A detailed description of it is given in the chapter on igneous rocks# . _

Cambrian Sedimentary Rocks

The lowest formation of the Cambrian sequence in the Huachuea

Mountains is tho Bolea quartzite, which lies on a surface of low relief formed by the erosion of pre-Cambrian granite# The Bolsa quartzite crops out in a continuous belt along the cast side of the range from the southern limit of the area mapped to Blackball Canyon# It also.crops out on the

4« Butler, B#S#, et# al.. Geology and ore deposits of the Tombstone District Arizona; Ariz. Bur. of Mines, Gaol. Series 10, Bull. 143, p. 12, 1938* ...

ridge between the Manila Mine and Sycamore Gallon in the northwestern

The nature of the contact between the Bolsa quartzite and the under­ lying granite is best seen in Sycamre Canyon* Here the contact is not obscured by float, as in most places* The pre-Cambrian granite is so decomposed for two to three feet below the contact that it can'easily be broken out with a pick. There is no fault gouge or evidence of movement along this contact, so it clearly seems to be one of deposition.

The decomposed material is probably the old weathered surface upon which the Bolsa quartzite was deposited.

Pre-Cambrian strata were folded and/ or faulted before deposition of the quartzite-Bolsa. This relationship is shown in the Mule Mountains, where Ransoms "’found a strong angular unconformity between the Pinal schist and the Bolsa quartzite* v:

The Bolsa quartette was formed by the cementation of buff-colored, cross-bedded sandstones and conglomerates* In this area a basal con­ glomerate with fragments varying in diameter from six inches to one foot, £ such as described by Ransoms from the Blsbee quadrangle, was not observed*

In the Huachucas the basal portion does not differ in any essential respect from the remainder of the formation. Coarse gravel beds are found through­ out the formation* Individual gravels are well rounded and are in most

5*. Ransome, F*L«, Geology and ore deposits of the Blsbee Quadrangle, Arizona* U.S. Geol* Survey, Prof. Paper 21, pp. 26-27, 1904. 6. Ransoms, F.L.,-Geology and ore deposits of the Bisbee Quadrangle, Arizona: U.S. Geol. Survey, Prof. Paper 21, p. 29, 1904. places not eiich larger* than a pea. Plate 11 shows the cross-bedding

and the coarseness of the gravel lenses* Concentration of dark

minerals In thin laminae or along crossbedding planes givesa grayish-

purplish cast to portions of the formation# V. - .

As no fossils have been found in the Bolsa either here or else­ where in southeastern Arizona, the exact geologic age of the formation

Is not known* Conformably overlying it, however, is the Cochise''' for­ mation which contains late mddle Cambrian fossila* The Bolsa quart- "

site is 430 feet thick in Bisbee and about 440 feet thick at Tombstone*

The Cochise formation, described by Stoyanow®, was not mapped as a

separate unit but was included in the overlying Abrigo formation* Its presence in the northern part of the Huachuca Mountains .was established by comparing strata there with the exposures of the Cochise formation at the type locality which is the Whetstone Mountains*

z A blue limestone with algae-like spherical bodies similar to those

in the upper part of the Cochise formation in the type section, is well

exposed along the road in the lower part of Garden Canyon. In the Whet­

stone Mountains the Cochise formation is 311 feet thick*

Lying conformably on the Cochise is the Abrigo formation* The

Abrigo is exposed as a continuous belt along the east side of the range from Blacktail Canyon to and beyond Garden Canyon for an unknown dis­ tance* It also crops out on the ridge between the Manila Mine and

Sycamore Canyon*

7* Stoyanow, A*A*, Correlation of Arizona Paleozoic formations: Geol* Soc* America Bull., vol* 47, p* 480,'1936. 8* Stoyanow, A *4* Correlations of Arizona Paleozoic formations: Geol* Soc* America Bull., vol, 47, p. 466, 1936* ■ The lithology of the Ahrigo formation is distinctive, so that the formation is easily recognized in the field. The JLbrigo has a thin-bedded structure produced by tl» alternation of thin, irregular beds of chert with gray, greenish gray and yellowish gray limestones. Towards the top of the formation the limestone beds aro more arenaceous. Sand grains are etched out by weathering, giving the surface of the rock a gritty feel.. The color of these higher beds is brown on freshly.broken surfaces and rust brown on weathered surfaces. Individual beds of lime- stone in the Abrigo are from one to three inches thick, while chert layers are, in general, thinner. Plate 12 shows the thinbedded struc­ ture of this formation.

The upper limit of the Abrigo formation, as mapped, is marked by a prominent lithologic change expressed in the topography of the area.

Beds above the Abrigo contact are five to eight feet thick and have been eroded back to form a series of lynches or steps which contrast strongly with the twenty to forty cliffs of the thinbedded Abrigo formation below.

The beds above the Abrigo formation are sandstones and limestones. .

Fossils collected from the Abrigo formation in various localities „ in southeastern Arizona are of Upper Cambrian age^. ...

' ,, The thickness of the Abrigo formation as defined by Stoyanow^-® is

430 feet in the Whetstone Mountains and 420 feet in the Bisbee .quad- : , rangle. The symbol used for mapping in the Huachuca area, does not 10

9 Stoyahow, A.A., Correlation of Arizona Paleozoic'formations: Geol* Soc. America Bull., vol, 47, pp. 467-469, 1936*

10 Stcyanow, AJL«, op. cit., p. 480. . : -11-

differentiate between th# Cochise formation and the Abrigo formation of -

Stoyanow and corrsspends to Abrigo limestone as defined by Ransom#, This unit is therefore from 'TOO to 800 feet thick, >

The upper limit of the Abrigo does not mark the end of Upper Cambrian deposition in Arizona, hying above it are the Copper Queen limestone

(81 feet thick) in Bisbee and the Rincon limestone.(42 feet thick) in the Whetstone Mountains^, Since there were no fossils collected in

Cambrian beds above the Abrigo, they,were not separated from the Devonian

Martin limestone in mapping,

Devonian Sedimentary Rocks

: The Devonian Martin limestone lies with apparent conformity on the underlying Cambrian formations. The Martin crops but from a point , approximately half way between Huachuca Canyon and Blackball Canyon to and beyond Garden Canyon for an unknown distance. It is also found in the Manila Mine area in the northwest corner of the range. In places it forms part of the hanging wall of the Crest Line fault where it is folded and faulted as the result of drag on the fault surface. The thickness in this area is therefore difficult to determine. At Bisbee and Tombstone : - the formation is 340 feet thick^, .. ;

. Lithologically the Martin limestone in the Huachucas is similar to the type section in Bisbee, It is predominantly a dark gray compact12 11

11, Stoyanow, A*A,, Correlation of Arizona Paleozoic formations: Gecl, Soc, America Bull,, yol. 47, P» 480, 1936,

12, Stoyanow, A^.,, Correlation of Arizona Paleozoic formations: Geol, Soc^ America Bull,, vol, 47, p. 486, 1936, / ...... -12-

limestone which weathers brown* on exposed surfaces* There are also limestone beds of light gray and pink. The brown of the exposed sur­ face serves to separate the Martin limestone from the light gray to .. white Escabrosa limestone above and from the dark brown Abrigo formation below. The exposure of Martin limestone in Garden Canyon is characterized by the presence of small, well crystallized patches of calcite from one to three inches across* The calcite is stained red by the inclusion of hematite,:which causes it to stand out from the dark gray ground mass of compact .limestone* : . \ ;

A number of fossils were collected from various exposures, and these establish the age of the formation'in this area as Devonian* In

Huachuca Canyon a specimen of Spirlfer hunaerfordi was found, and in the northwest corner of the range, about 220 yards south of the Manila Mine,

Atrvba reticularis was collected* * : . ■ v , :

Mississippian Sedimentary Rock®

The Escabrosa limestone is exposed on Huachuca Peak, in a small area just north of Garden Canyon and also south of Garden Canyon* It may be present in the Manila Mine area and in other places in the northern part of the range* To the west it is cut off by the Crest Line:fault* 13 The Escabrosa limestone averages 700 feet in Blsbee and 500 feet in 24* Tombstone It was not measured in the Huachucas* The section exposed

13# Stoyanow, A*A., Correlation of Arizona Paleozoic formations: Geol* Soc, Am. Bull*, vol* 47, p. 508, 1936.

14* Butler, B* S*, et al*. Geology and ore deposits of the Tombstone District, Arizona: Arizona Bur* Mines, Bull* 143, P* 14, 1938* .-13-

on Huachuoa Peak Is thick enough to Include all of the Esc&brosa and part of the overlying Naco limestone* .: -., : v ;

The Bscahrosa is made up of thick bedded, cliff-forming, light gray and white, massive limestone* A specimen of Homalouhvllitas sp. was collected in it in Garden Canyon*

Pennsylvanian Sedimentary Rocks

The presence of the:Pennsylvanian Naco limestone on Huachuca Peak is inf erred for two reasons* First, the section is thick enough above the:Devonian to include not only a}l the Escabrosa but also 300 to 400 feet of the Saco, Second, the topographic expression of the beds above the cliff-forming units definitely assigned to the Escabrosa is typical of the Naco * The upper, beds are thinner than those referred to the

Escabrosa.and weather to a :series of steps or benches* In Bisbee the beds of . kn o w Pemgylvanian age are 1180 feet thick. : . •

Permian Sedimentary Rocks'

' The nature of the contact between strata of; Permian and those of

Pennsylvanian age was not determined in the northern part of the Huachuca

Mountains * At no place i n :this area is there a continuous section in which rocks of these ages form a continuous series* The top of the

Permian formation is probably absent, also. At the head of Garden

Canyon a pre-Cretaceous valley, cut in the Persian limestones," has :. removed at least 2500 feet of strata. . : '

The Permian rocks are exposed at the head "of Garden Canyon, where they are bounded on the east by the Lyle -Peak:fault, ’this’ fault brings -14-

Permian and Cretaceous str&ta together, and are boundedon the west by the Cretaceous basal limestone conglomerate• Between these boundaries

Permian outcrops exterai in a nortitwest direction to a point roughly in line with the extension of Huaehuca Canyon and in a southeast direction off the area mapped* Other areas of Permian exposures are found in the' northwest corner of the range west of Blacktail Canyon, where the Permian beds hhve been thrust over Cretaceous rocks» . ^

The lowest Permian beds exposed in Garden Canyon are just west of the Lyle Peak fault and consist of red, soft thin-bedded limestones*

Higher in the section along the Garden Canyon Road are cliffs of massive gray limestone (see Plate 13)« A specimen of Euoiaphalus sp« was collect­ ed here* ■ —- ■ - -• -• - • ••.*:..

At the head of the Cation, just west of the point where it widens out to form Lone Cabin Valley, about 100 feet of black fetid limestone is exposed* The outcrop is less than one hundred yards from the cabin , whence the valley gets its name* A well-preserved- specimen of. Orroholo- trochus sp« was obtained here* Black, fetid limestone marks the top of ~ the Permian section at this point* Unconforrably above it lies Lower ? ;

Cretaceous limestone conglomerate« ' . v , v - -

At the northern end of Lone Cabin Valley Permian beds form the rim of the valley, and the section continues to the west-northwest, exposing an.additional.2000 feet of. Permian,sediments. These are.black.limestones, varying in thickness from one. to-four feet* In the saddle between Lone

Cabin Valley and McClure Canyon, specimens of Meekella sp* were collected*

Farther up in the section and west of the saddle on a ridge leading to a

small unnamed peak, a fauna of small gastropods, haying the " Permian : -15-

15 aspect” of Glrty1s Mansano fauna were collected# Lying batween the black Permian limestones and the Lower .Cretaceous limestone conglomerate are several hundred feet of red arkosic sandstones and red thin-bedded limestones* The exact age of these bedsis unknown, but since they are conformable with the underlying Permian limestones, they are probably, of

Permian age also* . v. ' . ..x,

In HLacktail CEinypn Permian limestones are exposed on the west side of that drainage on Sycamore Ridge. The only fossil remains found here were a Productus sp. and many crinoid stems about half an inch in diameter.

Permian strata form the hanging wall of the Crest Line fault in this area and are strongly disturbed by folding and/or faulting* x:.-i -x: 1

The Permian also crops out in the Manila Mine area. On the ridge to the east of the mine Permian strata are faulted against the Abrigo

formationw .... - ' to the _ north - and:are>•*_..■ n -thrust | over ' Cretaceous ... , - - : beds on the - south* t w . •

Permian strata are - gray thick-bedded limestones with prominent chert beds*

These chert beds are irregular in thickness but are commonly from two to four inches = thick. In places the chert forms nodules which when viewed at a distance give the limestones the appearance of a conglomerate * Near the top of the formation as exposed here is a brown quartzite about forty feet thick. ;Quartzitebeds in the Permian sequence have been reported from 16 17 the Canelo Hills and the Empire Mountains «* 16

15* Glrty, G.H., Paleontology of the Mansano Group of the Rio Grande Valley, New Mexico $ U*S, Geol. Survey, Bull* 389# Plate XI, 1909*

16. Feth, _J*H* Permian stratigraphy and structure. Northern Canelo - Hills, Arizona: Am* Assoc* Petroleum Geologists Bull.,vol» 32# pp-88-99# fig* 3, 1948* ' ":: . :::

17* Alexis, C.O., Geology of the Lead Mountain area, Pima County,Arizona.j Univ* of Arizona Library, Master’s Thesis (unpublished) p. 1939 —16«* *

Fossils collected from- the limestone in this area are Echlnoconchus

sp», Productus sp.. and Agplexus sp#

The Permian is also exposed to the south and west of the Manila

Mine, where it is"thrust over Lower Cretaceous beds* The Permian strata

are gray limestones with beds fro® one to four feet thick. Some quart­

zite is also present* Fossils collected up the canyon fro® the McFadin

residence were Fenostolla sp*, Plaeioglypta sp. and-large crinoid stems*

- - ' - Lower Cretaceous Rocks

Lower Cretaceous sedimentary and volcanic rocks cover most of the

area west of the Crest Line fault and nearly all of the western slopes

of the northern part of the Huachuca Mountains.

The best exposures of the Cretaceous beds are found on the west

side of the range between Lyle Canyon and. Scotia Canyon. Here the beds

stand in a nearly vertical position and are well: exposed from their .

contact with the underlying .Persian limestones on ‘ the east, westward :

normal to tho strike for throe miles, where they are in contact with

Tertiary volcanic rocks and/or late Tertiary alluvium*

: Parker Canyon Sections In the northern'part of the Huachuca

Mountains the entire Lower Cretaceous section is exposed in Parker

Canyon east of the Montezuma Pass to Cenelo Hoad* Parker Canyon

crosses this road in the SW* corner of the MW* quarter of Section 17,

R* 19 E*, T* 23 S* The base of the section is at the head of Garden

Canyon* - The road from Garden Canyon across the range to Sunhyside is -

approximately normal to the strike of the Lower Cretaceous strata. ’ -17-

Follow the road to the Sylvanla Ranch and there cross the ridge to the north which will put you at the head of Parker Canyon* Parker Canyon was chosen for examining the section because of the excellence of

Lower Cretaceous fossils exposed in its walls#

; Lower Cretaceous beds in this area have been divided by the writer into four formations, as follows; ..

Tertiary volcanic rocks and/or alluvium

Lower Cretaceous Feet : Upper clastic formation ...... 4290 • ; Limestone formation...... 540 tVAVe Lower clastic formation ...... 8000 " : Limestone conglomerate formation ..... 3300 Total ...... 16,130 :

Permian limestones J

The limestone formation is the only one definitely dated oh the basis of fossils. It is of Lower Cretaceous (Trinity) age. The lower clastic formation and the limestone conglomerate formation were included in the Lower Cretaceous because Trias sic or Jurassic rocks have not as yet been found in southern Arizona. The upper clastic formation was included with the Lower Cretaceous because it lies conformably on the: : limestohe formation. " 1 " '" '

The limestone cbnglOTOrate formation: The limestone conglomerate crops out on the west side of the range near the ere st from a point

’which is approximately on the projection of the trend of Huachuca .

Canyon southeast to and beyond Lone Cabin Valley. It probably continues to the southern end of the range and may be the same conglomerate as that ■18**

exposed near the top of Montezuma Pass• , .

The limestone conglomerate outcrops in several other localities in the northern part of the Huachuca Mountains, but faulting has made its exact nature obscure. Part of ■toe limestone breccia along the Crest-

Line* fault may have been formed from drag of this conglomerate. Hand specimens of the limestone breccia and the limestone conglomerate can­ not bo differentiated. The limestone breccia or conglomerate along the Crest Line fault on Sycamore Ridge may be in sedimentary contact with the Permian there. The ridge to the east and south of Woodyard

Canyon is capped with limestone breccia or conglomerate. It may result from drag of the limestone conglomerate, or it may be a farigloserate derived from an advancing thrust plate of Palesoic limestones and then covered by the thrust plate*

.The following description of the limestone conglomerate is based on studies of outcrops in Lone Cabin Valley, the head of Parker Canyon and in Copper Glance Canyon. At these localities there is no doubt of its sedimentary origin, v - ^ ' ' ; f :

:• Tim conglomerate lies with strong erosional and structural uncon­ formity on Permian limestones and red beds. At the head of Garden Canyon

2500 feet of Permian strata were removed before deposition of the lime­ stone conglomerate, but one and one half miles northwest on Lyle Peak these Permian strata are still present. To the south of Garden - C anyon the thickness:of Persian rentoved by erosion appear tobe greater than

2500 feet. This area was not mapped. -

The.limestone conglomerate is made up-of limestone boulders,' cobbles •19-

and other gravels,■ fdiich in general, though not everywhere, show a , gradation in size dependent on its distance from the contact with the underlying Permian. In the lower portion of the conglomerate, limestone, blocks are larger than in the upper portion. Angular to subangular blocks two to four feet long are not uncommon. The usual size range is between three and eighteen inches. These smaller pieces are round- ■■ ■ ■ - - ' - - ' - - •- - - ■ . , . ■ . .. : ed to subrounded in outline. The absence of rock types other than lime­ stone and chert is remarkable.

. In the upper portion of the limestone conglomerate as exposed at the head of Parker Canyon near, the contact with the overlying red shales the conglomerate is finer. ..The larger blocks are absent, and the size lunge drops to between eight and two inches. . The' matrix contains not only limestone but also appreciable amounts of red shale similar to that in the overlying beds, A zone separating beds containing mostly limestone gravel from the overlying red shale which contains none is v - less than six inches thick.

Volcanic activity during the deposition of the limestone conglomerate is shown ty the presence of a vesicular flow about 2500 feet below the top of the formation. The flow outcrops along the trail between the Sylvania

Ranch and Huachuca Canyon at a point southwest of Lyle Peak. Neither its lateral extent nor its width were, determined.

Gravels composed of lirostone, volcanic rocks, quartzites, and shales were found near the top of the limestone conglomerate in Copper

Glance Canyon. Here the limestone makes up less than half of the con­ glomerate. The elastic materiel appears to have been derived from beds similar to those overlying the conglomerate. The beds from which the -20*

clastic and Tolcanic gravels were derived are not necessarily older than the lower portion of the limestone conglomerate*

The source:of the limestone gravels.in the conglomerate is shown by the fossils which are found in them. They include such Permian and Pennsy­ lvanian forms as Dictyoclostus so., Euomhholus sol, and Beljlemphnp ep.

Ko definite evidence indicating the presence of Lower Paleozoic rocks in • the conglomerate was found*

The topographic expression of the limestone conglomerate varies,, depending on its limestone content. Where the conglomerate is composed mostly of limestone, it forms high ridges# At the head of Parker Canyon the limestone conglomerate rises so high above the more easily eroded red shales and sandstones that it appears to lie horizontally on them# Hot until the contact is mapped is it perfectly evident that the red shales lie conformably on the limestone conglomerate#

The thickness of the limestone conglomerate varies between 1300 and

3300 feet in the northern part of the Huachucas# It appears to be even thicker in the southern part of the range*

Lower clastic formation* Overlying the limestone conglomerate conformably is a series of beds of red shale, sandstone or quartzite, volcanic flows and a few thin limestone beds# The shales, sandstones, quartzites and volcanic flows are found throughout the section but vary in their relative proportions in various parts of the same section# -21-

The section is as. follows t .

Idmestono formation . - v : : :r ' V,v

- Lower clastlo formation: • ^ - ::: ;• . ;;; .m --.-; feet ; Andesite_flows (see chapter on Igneous rocks) 2000 v Red shale and brown to buff, fine-grained, : •. ■ ; v croBC-bedded sandstones or quartzites in ■ nearly equal proportions ...... 2000 Dacite porphyry flow (see chapter on igneous rocks) ...... 300 Red shale and brown to buff, fine-grained, : crossbedded sandstones or quartzites in nearly equal proportions ...... 1700 • Red shale with subordinate amounts of fine-grained, crossbedded sandstones and .! quartzites, green and yellow shale ..... 500 Dacite flow (see chapter on igneous rocks)...... •.«« 300 Red shale with subordinate amounts of fine-grained cro s sbedded sand stones and quartzites, green shale and ^yellowish shale ...... ,. 12CX) ...; ; , - , Total ...... 8,000 .

Limestone conglomerate formation

'' Fossils" are very scarce in the lower clastic formation. A thin ; - oyster reef was found just below the andesite flows in the upper portion • of the formation but specimens were so fragmental that they could not be identified specifically. The sand stone and shale beds are apparent­ ly unfossiliforous except for petrified wood*

Petrified wood was found in a sandstone bed hear the base of the

section* The locality is just below the trams! of the Eureka Mh e * J

The.wood m s identified by Mrs* R» A* Barrow of Tucson, Arizona, as

Araucarloxvlon sp. This is the genus which is found in the Triassic -22-

Shinaruop conglomerate and Chlnle formations of northern Arizona ^

It is also the same genua collected by Stoyanow and identified by

Mrs* R* A* Darrow from the Lower Cretaceous Lowell formation in Bisbee,

Arizona. On the basis of wood structure alone it is not possible to make an age determination by using this genus*

The following description by Mrs. Darrow was based on thin sec­ tions made of the wood: (See Plates 14 and 15*)

1. Annual rings not distinct*

2* Uniseriate and sometimes biseriate bordered pits (typical Araucarian pitting) on the radial walls of the tracheids*

3* Not pits on tangential walls*

4* Rays uniseriate, ftom one to eighteen or twenty cells high*

5* No branch traces in tangential section, thus ruling out genus Woodworthla*

The volcanic rocks described from the lower clastic formations in

Parker Canyon did not show conclusive evidence of their, extrusive origin*

It is possible that some are sills. Volcanic rocks exposed in Blacktail

Canyon and Bear Creek are clearly of extrusive origin. Their exact stratigraphic position is unknown, but they are certainly in the lower clastic formation.

An aBygdaloidal basalt in Blacktail Canyon lies southwest of the

Crest Line fault contact between the Permian and Cretaceous strata on the 18

18. Knowlton, F.H., The fossil forests of Arizona: American Forestry, vol* 19, p. 218, 1913*

19* Daugherty, L* H., The Upper Triassic flora of Arizona: Carnegie Institution of Wash. Pub. 526, pp. 86-89, 1941.

20* Stoyanow, A. A. personal communication, 1948. east side of Sycamore Ridge and near the top. This basalt is described

in the chapter on igneous rocks.

During the; examination, of t h e . lower. clastic. formation south of Lone

Mountain, the top of a volcanic flovr was found about two tenths of a

mile west of the Wakefield Camp. The concentration and increased size of

gas cavities toward the top of the.flow and.the flow,structure visible'

in the rock show its extrusive nature unmistakably. Further evidence is

that the sandstone which overlies the flow has not been altered at the

contact. . v ■ T • ■ : :: ^ : V-'V; : .

Strati.graphically-higher in the lower clastic formation than the

flow in the Lone Mountain. area are beds of agglomerate. • These beds are made up of pebbles and gravelo apparently deriyed from a volcanic flow

or flows similar to that described above. The prevalence of red in the

shales of the clastic formations may be :due in part a t ; least to the

erosion of volcanic flows and the consequent oxidation of their iron

content. - Lr. ■ ; • y

Limestone formation* The limestone formation lies with apparent

conformity on the lower clastic formation. It is 540 feet thick and

consists in greater.part of gray limestone beds. Associated o r ;inter- bedded with the limestone are other beds of yellow to greenish yellow

shale o M brown sandstone or quartzite. In Parker Canyon the section -24-

is as followsi

Upper clastic formation Feet

Limestone formation Gray massive limestone in one to three foot beds...... 170 Mostly sandstone or quartzite and yellow to yellow green shales, remainder gray limestone...... 200 Gray limestone in one to three foot beds with a few sandstone and shale beds...... 170

Total 540 Lower clastic formation

In the upper part of the middle two hundred foot member are several very fossiliferoua beds. : Reefs made up almost entirely of

Ostrea ragsdalei are present (see Plates 16 and 17). In the yellow shales numerous specimens of Glaueonia branneri (Plate 17) are present. ' - ' • ' ' ■ 21 Ostrea ragsdalei I s an index fossil for the Glen Rose , and ■ _ - •' * 22 Glaueonia branneri occurs throughout the Trinity group . These fossils were first reported from the Huachuca Mountains area by

Stoyanow •

The limestone formation was used as a marker in working out the

structure of the Cretaceous rocks. It was followed north from Parker 232122

21. Hill, R. T., The paleontology of the Cretaceous formations of Texas; The invertebrate paleontology of the Trinity division: Proc. Biol. Soc. Wash., p. 23, 1893. - V - - - • : ' :: 22. Hill, R.-T.,.op; cit., p.34

23. Stoyanow, A., Fossiliferous zones in the Cretaceous and Tertiary deposits of southeastern Arizona (Abstract): Geol. Soc. Am., Proc*, p. 2 % , 1936; Lower Cretaceous stratigraphy in southeastern Arizona, Geol. Soc. Am., Mem. no. 36, p. 30, 1949 -25- .

Canyon to Woodyard Canyon, where it has almost 'pinched out* At the ' last outcrop mpp®4 it is less than twenty feet tMck,: whic& suggests ' that the jnorthern end of limestone depositicn is reached here* r ' "

Upper clastic^ formation: The upper clastic formation lies with apparent,conformity on the limestone formation. The section as measured in Parker Canyon is as follows* ij v^.v^'-vy

1 ' C l

Tertiary alluvium - • : 3 v /• • Feet'

Upper clastic formtion . : , r.--. ; ; : ■ - - ' Volcanics (?), red shale and arkosic sandstone ...... • 100 1 Covered by float and pediment , . gravels ...... i V 1190 Several beds of conglomerate with rounded to subrounded pebbles of v- ^ ^ volcanic material (see Plate 10) interbodded with red, yellow and brown shale beds 750 Mostly brown to buff, fine-grained crossbedded sandstones with red ; shale and volcanic flows (?) ...... 1350 Red to purple shales with some buff. fine-grained sandstone beds ...... 900 ■I Total_;...... ^-4,290 , hi; -'ii

IV.:- . V h nblrlll;-" 1, - 1 - he r : ; Llmstone formation ;:i’i. hiiviivi;-: .1 i;:"'1} '‘h

In' Ferosa. Brushy and Algerita Canyons the upper clastic formation contains beds of conglomerate made up in part of limestone gravels. hfirv^i l'. rv./ probably derived from Paleozoic formations• 1The componentsfof t6e Tl i. >" * •* . : - ' . : conglomerate average less than three inches in length and are rounded to subrounded-in outline. Most of the•conglomerate appears to have been derived ftrom older Cretaceous fornatiohs* -26-

In Parker Canyon there_ls a gap of one mile between the western- most outcrop of nearly vertical- Cretaceous beds and the relatively flat- lying Tertiary volcanic rocks. ; In order to determine the nature of this contact, the southern end of Lone Mountain was examined. Lone Mountain is south of the area mapped and is the southernmost outlier of the Canelo

Hills. The mountain is essentially a down-dropped block of Tertiary volcanic rocks, mostly agglomerates, within the Cretaceous section.

This suggests that the contact between the Tertiary volcanics and the

Cretaceous beds in Parker Canyon may also be on a fault. If such is the case, tire sedimentary contact between Cretaceous strata and Tertiary i volcanic rocks will not be found in this area. In the Northern Canelo 24 -- ; - Hills, Feth has reported a structural unconformity between these for-

•' - '• ' , - - • nations.

Correlation of the Cretaceous Section

The following correlation table is based on information collected by : 1- : ' ' : " ' 25 : , ■/ ; Inlay from his work in Sonora and various other published sources.

The thickness of the Upper Cretaceous in the Cabullona area is taken from 26 " ! "■ ..... - • ' - :.-' Taliaferro • The Cretaceous section in the Huachuca Mountains is includ- ■ : c : - : ed for comparison. ; f *2526

24* Feth, J.H., The geology of the Northern Canelo Hills, Santa Cruz County, Arizona, Ph.D. thesis, 1947, pp. 41-45. ■■ : : ■; !■; : : ' 1 : 25. Imlay, R. IT., Paleogeographic studies in northeastern Sonora: Geol. Soc. Am. Bull., vol. 50, pp. 1736-1738, 1939. ;

26. Taliaferro, N.L., Upper Cretaceous sediments in Mexico: Jour.Geol., vol. 41, p. 16, table lj 1933.^ y j •27-

CRETACEOUS OF SOUTHEASTERN ARIZONA AMD HOBTHBigrRmf RQHORA

. - . : : ' ' ; • . ■ Blebee,Arisona Cabullona i Sierra de (Siena de Huachuca Mountains, Area Sonora i San Jose,Sonora : los Ajos, Arizona t '______i Sonora ! Upper t Cretaceous ( 3,000 I Upper Clastic 4290 Lower Cintura 1800 Cretaceous *---- — ------1 * "! Linestone 540-20 Mural * 650 t 1,400 S Present i Present i • formation t l | f - -. - :.. .-. - . .- -.-.■ .. -. -.-.— i 1 Several t t Lower Morita $ 1800-2000 i 5,000 i 2,000 1 thousand l t clastic 8000 Lower Cretaceous * t t - - ' - ... -_____ - ...... t v •' $ 1 ( Glance : 0-1500 i 2,500-3000 i , * 5,000 $ ( Limestone s 1 t conglomerate 1300-3300

Conelation of Cretaceous in Sonora Cretaceous section, and southeastern Arizona (after Inlay Huachuca Mountains (this paper) and others)•

All thicknesses in feet. -28—

Distribution of Lower Cretaceous Volcanic Rocks .

Volcanic flows in the Lower Cretaceous have been described by 27 L&sky . from the Little Hatchet Mountains, New Mexico. This area lies

80 miles cast northeast of Biebee. The Cretaceous beds there are rough­

ly equivalent in age to the Bisbee group, but differ from it by being

much thicker (13>000 to 24>000 feet) and-by containing several volcanic

flows. Ransome* s subdivision of the Bisbee group could not be used in

this area. Several periods of erosion occurred during their deposition,

resulting in wide variation in the thickness of individual formations.

found volcanic rocks in the Lower Cretaceous section of

southern Sonora.near Arivechi, which is approximately. 170 miles south of

the International Boundary, near Douglas, Arizona. This section totals

10,000 feet in thickness and consists of-coarse" sandstones, shales, -

andesitic lavas and limestones. ; .

Volcanic rocks have been reported among rocks believed to be of Lower

Cretaceous age in the Courtland-Cleeson region northeast of Bisbee by 29 Wilson • Here thin andesite flows (?) occur in a thick succession of

clastic rocks. ..." v 272829

27. Lesley, S.G., Geology and ore deposits of the Little Hatchet Mountains, Hidalgo and Grant Counties, New Mexico, U. S. Geol. Survey, Prof. Paper 208, pp. 1-2, 1947.

28. King, R« E., Geological reconnaissance in Sierra Madre Occidental of Mexico: Gaol. Soc. Am. Bull., vol. 50, Plate 5, 1939.

29. Wilson, E. D., Geology and ore deposits of the Courtland-Gleeson region, Univ. Ariz. Bull. 123, pp. 21-22, 1927. -29**

Tertiary Rocks

The Tertiary rocks of the Huachuea Mountains are divided into two main groups• They are the Tertiary volcanics and the Gila conglomerate*

The contact between the two was not observed, but the Gila conglomerate contains material derived from the Tertiary volcanics and is therefore younger* The Tertiary volcanics lie in the southwest corner of the area mapped* Access to the area is by a road leading to the Hathaway Ranch buildings* This road joins the Montezuma Pass to Canelo Road where the latter crosses Parker Canyon*

Tertiary volcanics form the first line of low hills to the wost of the northern part of the Huachuea Mountains where they are called the

Canelo Hills* The area mapped is the southern end of the Canelo Hills*

The trend of the hills is west northwest* The Montezuma Pass to Canelo

Road follows the lowest area between the Huachueas and the Canelo Hills and roughly marks the eastern limit of the volcanic outcrops in the area mapped.

The volcanic rocks give the. hills an overall red to brown color* As * exposed in Parker Canyon and in Collins Canyon they are mostly rhyolite porphyry flows with minor amounts of tuffs and volcanic agglomerates* In parts of the flows, pieces of solidified volcanic material have been incor­ porated and arranged parallel to the line of flow, (See Plate 22.) Several hundred feet of gray to red tuffs and agglomerates are exposed in Collins

Canyon, Some of the tuffs have been laid down in beds i to one inch thick.

Flagstones up to two feet long can be broken out of these beds (See Plate

22)* The volcanic agglomerate in.Collins Canyon is not thick*., It con- .30-

taint? a few cobbles-of Paleozoic limestones* --

Thin sections were made of the rhyolite porphyry flow and the tuffa- ceous sandstone* Their description is given under igneous rooks;-

The volcanic agglomerates in the southern mid of Lone Mountain are derived from rhyolite porphyry flows. Their development is believed to have taken place at a time closer to. that when the flows were extruded than to the time of deposition of the Gila conglomerate, for the follow­ ing reasons: • ■ r.: : :V:;- :

First, they < are firmly cemented or conrolidated while the Gila con­ glomerate is not* ■...;v:. ' '' V r : :V;.

Second, the red, slabby, tuffaceous sandstone from Collins Canyon, as shown on Plate 21, is present in volcanic agglomerate beds* In the

Lone Mountain area they are thin and lenticular, evidently deposited on an uneven surface by small streams*

Third, limestone gravels form a minor part in the agglomerates exposed in Collins Canyon and Lone Mountain but are a major constituent of the Gila conglomerate as exposed in the northern part of the area*

The thickness of the Tertiary volcanics is not known# An estimate of 4,000 feet was obtained by assuming that the volcanic rocks have an average dip to the southwest of ten degrees# The average dip may be greater in which case the Tertiary volcanic section would be oven thicker# 30 ' : Imlay estimates that the Tertiary lavas in northeastern Sonora are over

5,000 feet thick# .

The Gila conglomerate: The conglomerate beds are exposed between 30

30, Imlay, R» ¥#, Paleogeographic studies in northeastern Sonora, Bull, Geol# Soc# of America, vol* 50, no# 11, Kov# 1939, p# 1738. -31-

the Basin Ranga fault on tho north side of the Huachuca Range and the

Boboconari River. . . . : ,

Neither the base nor the top of this conglomerate has beenfound.

An eight inch test well northeast of Fort Huachuca penetrated 917 feet of conglomerate without going through the entire formation. Whether this entire thickness was in the Gila conglomerate is not known. ' : ,

The Gila conglomerate, as exposed near the Basin Range fault, includes boulders, cobbles, and pebbles* The boulders range up to three feet in diameter* As the beds are traced northward away from the Hua- ~ chucas, the conglomerate rapidly grades into finer sediments.

The conglomerate is composed of gravels derived from strata that, range from pre-Cambrian to Tertiary in age. The following are estimates of the composition of the conglomerate from localities within 200 yards of the Basin Range fault, . I ■ '

1 * Cretaceous and Tertiary rocks 80% Paleozoic limestones 20%

2. Cretaceous and Tertiary rocks 90% Paleozoic limestones : 10%

3. Sandstone or quartzite : ' /: ; . : 55% Paleozoic limestone 20% Cretaceous and Tertiary rocks 15% Granite 10%

A large boulder in the conglomerate was derived from an earlier conglomerate. The composition of theboulder is as follows:

Paleozoic limestones 35^ Paleozoic (?) chert . 15% Cretaceous and Tertiary rocks 50%

Plates 23 and 24 show this conglomerate* -32-

About one mile north of the Basin Range fault the Gila conglomerate, as exposed in Sycamore Canyon, is much finer* Here'it 'is composed of angular to subrounded gravels of Tertiary volcanics. Paleozoic lime­ stones, and Cretaceous clastic and volcanic rocks. The individual pebbles are from one to two inches long with a few up to five inches in length.

The Gila conglomerate has been disturbed by folding and/or faulting and dips up to 45 degrees.

Near the railroad station in Elgin about 15 miles northwest of the

Huachuca Mountains, fine grained clastic rocks are exposed in banks of a creek, (see Plate 25)•

They are limy clays, gray siltstones and sandstones. A few badly weathered pieces of volcanic rock, ranging up to four inches long were found in them. These beds are believed to be equivalent in age to the

Gila conglomerate found near the Huachuca Mountains* They ware deposited farther from the mountains and are consequently made up of smaller parti­ cles. The limy character of the beds suggest that they may have W e n deposited in a lake occupying the intermontane basin (Sonoita Basin). :

Faulting and/or folding has disturbed these beds. The Gila conglomerate is of Pliocene age.

Quaternary Rocks

: No attempt was made to map separately the disturbed Gila conglomerate from the undisturbed gravels lying on it. In general these gravels dip

gently toward the present drainage systems. The following section indica­

tes two period of gravel deposition. This section was measured about two miles northeast of "the Basin Range fault where it crosses Coyote Canyon*

Surface Thickness ,

Upper gravel Reddish orange conglomerate of which one half the volume is made up of granite and quartzite cobbles and ' boulders ranging up to 18 inches : long ...... 15 feet

Lower gravel Reddish brown conglomerate of which ^ : one quarter the volume is made up of cobbles ranging up to 6 inches long ...... J25 feet • Total ...... AO feet

Creek bed

IGNEOUS ROCKS

The igneous rocks of the northern part of the Euachuca Mountains are divided on the basis of age into four groups: the pro-Cambrian granite, the Lower Cretaceous volcanic flows, the Tertiary volcanic flows, and the post Lower Cretaceous intrusive rocks which are associated with the mineralization of the area.

Pre-Cambrian Granite

The pre-Cambrian granite is exposed along the eastern and northern flanks of the range. It is cut off to the east and north by the Basin

Range fault. To the west and south it is in sedimentary contact with the

Bolsa quartzite, except for Sycamore Ridge, where it is in fault contact with Paleozoic limestone. •34-

In the area mapped (Plate l), the pre-Cambrian granite covers twenty- five square miles*

The granite was eroded to a surface of low relief before the depo­ sition of the middle Cambrian Boise quartzite. In general, the granite is very coarse, with well developed crystals of orthoclaee up to one and one and one half inches long. It has been intruded by dikes of quarts, aplite, and lamprophyre. Most of these dikes are probably of pre-Cambrian age*

The granite is broken by a strong joint system which in places has been mineralized subsequently by fluorite deposited in open fissures, which indicates that the granite was relatively near the surface during mineralization* The fluorite mineralization is probably post-Cretaceous in age.

The granite specimen described below was collected in a road cut one half mile north of the north gate to Fort Huachuca* The granite is sheared* The shearing probably occurred during pre-Cambrian time in a period of mountain building during which the granite was at great depth below the surface*

The specimen studied in thin section is a gray, coarse-grained granite. It is essentially feldspar and quartz* The feldspars are microclino, perthite, and oligoclase, all being anhedrons of considerable

size and many including flakes of white mica* The quartz occurs either in large crystals or as aggregates of small anhedrons with sutured con­ tacts* The quartz shows pronounced wavy extinction* Muscovite, the only accessory mineral, shows bending of its crystals and wavy extinction* Lower Cretaceous Volcanic Rocks

The stratigraphic occurrence of the Lower Cretaceous volcanic flows

has been discussed under stratigraphy (page 21). Here is presented a

petrographic description of those flows of which thin sections were made*

Parker Canyon Section: In the lower clastic section of Parker Canyon,

three igneous bodies were found« These are tabular, apparently conformable

to the bedding, and may therefore be either sills or flows. They do not

show positive evidence of extrusive origin, but they are tentatively

classified as such, because flows have been found elsewhere in this area

in the lower clastic formation.

The lowest flow (?) in the lower clastic formation is 300 feet of

dacite, the base of which is 1200 feet etratigraphically above the top

of the limestone conglomerate formation. In hand specimen, it is grayish

green aphanitic rock with some conspicuous phenocrysts of feldspar. There

are a few cavities on the weathered surface, probably due to the weathering

out of the feldspar phenocrysts*

In thin section the dacite shows a "felty* texture, consisting of

closely, random packed, platy, plagiodase crystals* The interstitial

spaces are largely filled by orthoclase and quarts* A few phenocrysts of orthoclase and plagiodase are present, making up less than ten per

cent of the rock* Alteration has crowded the feldspars with sericite, kaolin!to, and chlorite, and in some places also with epidote and calclte.

The epidote also occurs as grains in veinlets. Chlorite flakes and grains

of magnetite are widespread in the section. A second flow occurs about 4700 feet above the base of the lower clastic formation* It is about 300 feet thick* This rock is a red aphanitic dacite porphyry*

In thin section, it consists essentially of a fine-grained ground- mass, made up of tiny lath-shaped plagioclase crystals, with interstitial quartz grains, and showing a heavy decoration of alteration products*

The phenocrysts of quarts and feldspar make up twenty percent of the rock.

The phenocrysts of feldspar are oligcclase, but the feldspar of the groundmass Is undeterminable, due to alteration* Kaolinite and sericite are the principal alteration minerals and are quite common in the .section*

The quarts is commonly more or less rounded and corroded with inlets of groundmass* Magnetite grains are found throughout, the"section* Much of the magnetite has altered to hematite, giving the rock part.of its red color* ' : : ,

The upper 2,COO feet of the lower clastic formation consists of volcanic flows (?) of andesite and quarts latite* The quartz latlte wad collected near the base of the volcanics*

In hand specimen, the quarts latite is a dull gray, aphanitic - rock containing dark gray spots, up to one half inch in diameter* - i "■

In thin section, the quarts latite was found to consist of lath­ shaped plagioclase crystals in a felty texture, with "about fifteen per cent of interstitial quartz and about twenty-five percent of orthoclase* '

The phenocrysts of plagioclase, orthoclase, and perthite are from one to two millimeters long and make up three percent of the rock* All the feldspars are altered to kaolinite, chlorite and a little sericite*

Chloritic pseudoabrphs after some,tabular"or prismatic mineral"are -37-

cosimoR and are urually associated with magnetite, serlcite, and

occasionally, ©pidote* 2 Apatite is the common accessory mineral in

crystals up to .06 millimeters long*

Andesite was collected in the upper part of the 2,000 foot section:

of flows. In hand specimen, it is a dull greenish-gray aphanitic rock,

with a few phenocrysts of feldspar, dotted with grains of magnetite,

which has partly oxidised to limonite* A few cavities are observed

on the weathered surface. \ .....

In thin section, the andesite shows Hrachitic* texture," consisting

of densely packed slender crystals of plagiocla.se with fluxional arrange­

ment. Phenocrysts of plagiocl&se, .orthoclase, and porthite make ;Up

about ten percent of the rock. The feldspars are largely altered to

' kaolin!te, sericlte, chlorite,, epidote, and calcite. . Patches.of chlorite

are scattered through the section, hut no crystal form is discernible.

A very little quarts is.present. - Apatite crystals are common. Grains -

of magnetite, which are partly altered to limonite, are widely distri­

buted# t.A. - - l •: ; y

Volcanic flow in Blacktall Canyon:. An amygdaloidal basalt occurs in

the lower clastic formation of Blackball Canyon. The exposure from which

the specimen was collected lies cn the east side of Sycamore ridge near

the top, where the Crest Line fault has. t hr unted Permian limestone over

the Lower Cretaceous. .. -y; /.uv.,-.

In hand specimen, the basalt is a purple scoriaceous rock with

cavities filled with calcite and other minerals*

In thin section, the basalt shows "folty* texture,.consisting

essentially of random packed, tiny, lath-shaped feldspar;crystals. The feldspar crystals are- so heavily crowded with soricite, calcite, and chlorite, due to alteration^ that they cannot be determined* Blacks ami brown dusts of iron oxides are widely distributed, Euhedral rutile is unusually abundant* The cavities are largely occupied, by calcite with subordinate chlorite and sericite, ' ; '

Tertiary Volcanic Rocks

The Tertiary volcanic s apparently lie with"strong structural and erosional unconformity on the Lower Cretaceous-beds* The distribution, thickness, and character of the volcanic rocks were discussed under stratigraphy (page 29)* The following is a detailed description of the two specimens chosen as reprctentative of the volcanic rocks,

A specimen of the flow rock collected near the Hathaway Ranch - buildings was determined to be rhyolite porphyry. In hand specimen, it is purplish red with conspicuous phenocrysts of quarts and feldspar about two millimeters long, embedded in a reddish aphanatio groundmass* J

. . .In thin section,-the rhyolite porphyry shows a pronounced porphyritic texture with euhedral orthoclase and quarts as phenocrysts* The feldspar is largely but not uniformly altered to clay minerals, while the quarts is corroded and embayed with groundmass. The groundmass is in part glassy and in part cryptoerystalline and in many places shows excellent sphefulitic texture. Flow structure is shown by hands of- spherulites or by layers of glassy and cryptocrystalline groundmass, which usually wrap around the phenocrysts,

A specimen of calcareous tuffaceous sandstone was collected from beds lying between rhyolite porphyry flews. These bods are exposed in

tho stream bed of Parker Canyon between the Hathaway Ranch buildings and -39*

the Canelo to Montezuma Pass read, !

In hand specimen, the sandstone Is a reddish, fine-grained, dense,

rock, : . . . . - : •; ■ - . , ; ■ ; :

In thin section, it is essentially cryptocrystalline, so that its ’

constituent minerals could not be determined. Abundant tiny fragments

with concave outlines give rise to an "ash structure”. The fragments

were glass and have now become crystalline by devitrification. Larger

corroded fragments of quarts are also common. Only & few feldspar crystals

are present. Grains of calcite are abundant. Flakes of biotite are

occasionally seen, : ; . .; ; \ ;

Post-Cretaceous Intrusive Rocks

Large intrusive bodies of post-Cretaceous age were not found in

the northern part of the Euachuca:Mountains, with the possible.exception

of sills (?) in the Cretaceous rooks. Quarts veins and lead and copper

minerals in this area are probably related to an igneous stock in the- 31 southern part: of .the range, . Heber reports that this stock crops out west of the Crest Line fault, ,During a .reconnaissance in the, southern

end "of the’range east of :Montezuma Pass the writer found that the Paleo­

zoic formations had .been intruded by a granitic stock, '

If it is assumed:that the igneous stock in the southern part of the

range is the source.of the min eralizing.solutions which formed the Manila

Mine ore body, a tentative age for the period of. intrusion can be-assigned, 31

31 Weber, R, H,, personal communication, April, 1949. Surfsea capocures near the Manila Mine, show that the mineralization occurs both in the Paleozoic formations# forming the overthrust block# and in the Cretaceous strata forming the lower plate* The mine workings were not accessible, but a study of the dumps' revealed that the mineralised fissure cut through the thrust fault plane, as both the Paleozoic lime­ stones and the Cretaceous strata were mineralized* The mineralization is therefore post-thrusting# hence the intrusion of the stock in the southern portion of the range is probably post-thrusting*

GEOLOGIC STRUCTURE

. ’ The northern part of the Huachuca Mountains constitutes a complete geologic cross-section of Basin and Range Province structure* It'also shows the nature of the folding and faulting of the Laramide Revolution, and

Tertiary time*

Internal features of the northern part of the Huachuca Mountains:

The most striking thing about this area is the large size of the struc­ tures and their excellent exposures* The range is essentially a fold or folds that have been broken by a reverse or thrust fault and were then subject to normal faulting of the Basin and Range type*

In addition to these large structural features there are smaller structures associated with them, such as drag folding and reverse fault­ ing associated with the Crest Line thrust fault and other structures connected with the mineralization of the area* These features could not be mapped on the scale of map available* Structure Elements

The various elements in the structure of the northern part of the Huachucas will first be described. Structures developed in pre-

Laramide time will be discussed later under structural history*

Folds

Rough Canyon Anticline$ The Rough Canyon anticline is a major structure in the Huachuca Mountains• Its northwest trend follows that of the range. The northern nose is in Algerita Canyon, about half a mile east of the Foster Ranch buildings (now the Page Ranch), From this point it extends to the southeast for a distance of. six miles

(the limit of the area mapped)# Its extension beyond this point was not mapped. The width of the structure cannot be determined because its northeast flank has been dropped down along the Lyle Peak fault.

This fault has the same trend as the axis of the fold, suggesting a ' * genetic connection between the two. If the fault is along the axis of the fold, then the width of the western limb through Parker Canyon is three miles.

Except that the eastern limb has dropped down on a fault, the

Rough Canyon anticline has been little modified by major faulting.

Rough Canyon Synclines The Rough Canyon syncline lies adjacent to and northeast of the Rough Canyon anticline at its northern end.

The structure is outlined by the limestone formation, except for its northwest nose at the head of Algerita Canyon where the formation comes within 150 yards of completely surrounding it. The measurements given are based on the outcrops of the limestone formation. The southeast Bose of "the structure lies on the crest line of the’Huachuca Mountains at the head of the northwest fork of Huachuca Canyon. The axis of the syncline trends north 60 degrees west from this point for one and one half miles to the head of Algerita Canyon. The syncline is one half mile wide.

The axis of-the syncline extends west northwest along Algerita

Canyon where the synclinal structure becomes less pronounced and apparent­ ly disappears altogether before the mouth of Algerita Canyon is reached.

The axis can be followed southeast for one mile from'the southeast nose as outlined by the limestone formation. Its further extension to the southeast is not known. • -

Drag Folding: Drag folding is well developed'on the Crest Line thrust fault, where the beds have been isoclinally folded in places. The drag v along the beds indicates movement of the hanging wall from the northeast*

Away from the fault zone the folding becomes less intense* - ;

In Woodyard Canyon the Lower Cretaceous strata have been overturned by drag along the Crest Line thrust fault. These strata Were folded before faulting during the Laramide Revolution, At the end of that orogeny, they probably had the same attitude as the Lower Cretaceous strata farther south in Algerita Canyon. That is, they dipped to the southwest.

During the overthnisting the Cretaceous strata in Woodyard Canyon - were dragged along the fault surface* The result was the overturning of these strata, so that they now dip to the northeast* The strata in Alger­ ita Canyon were farther below the thrust fault surface and were therefore less disturbed by the movement on the fault plane,'

The evidence for the thrusting causing the overturning of tbo beds in Woodyard Canyon is seen by following the formations north from-Algerita Canyon* About ono half-rail© northwest of the Foster Ranch buildings

(now the Page ranch) the Cretaceous beds as exposed In Algerita Canyon dip 25 degrees to the west northwest. To the north, the dip gradually

Increases, and the strata begin to swing to the west. This change is especially strong near and In Ferosa Canyon at the southwest end of the ridge formed by the Paleozoic limestones thrust over the Cretaceous.

This suggests a genetic relationship. Here the strata swing from north

20 degrees west to north 50 degrees west within a quarter mile* The change in dip is more pronounced* In the same area the dip of-the>strata changes from AO degrees to the west southwest, to vertical, and finally the strata are overturned, so that they dip 66 degrees to the northeast*

The drag in the Cretaceous strata in Wbddyard Canyon shows that the upper thrust plate moved from the northeast,... -

Folding of the Tertiary rocks: The Tertiary rocks are all disturbed, but it is not known whether this is due to folding or faulting. The Ter­ tiary volcanlcs are competent and could transmit compressive stresses.

Folding of -these rocks woiild be possible. _ H ••

The Gila conglomerate (?) is semi-consolidated and therefore in- , • competent* If the conglomerate is folded, it may be the reflection of the underlying competent beds or it is due to drag along;the thrust faults*

Folding of the thrust fault: The Crest Line thrust fault dips about

A5 degrees to the east northeast from"Garden Canyon to Huachuca Canyon. In the Manila Mine area, the fault is flatter (less than ten degrees) and dips

to the north. This relationship can be explained in three ways* One, the

fault surface has been folded; two, rotation of the fault surface by block

faulting; and three, the fault surface as originally formed was curved* Any one of these or any combination of. them may be the explanation* It

is known, however, that arching on a broad scale took place subsequent to 32 thrusting in the Northern Canelo Hills, and it is probable that the

thrust faultIplane in the Huachucas was also arched* The original dip

of the Crest Line fault between Garden and Huachuca Canyons may there­

fore be less than the 45 degrees observed now*. .- ; ; >

Faults

The faults mapped in the Huachuca Mountains are of two main types

as to origin. The earliest faulting is believed to be related to com­

pressive forces which first folded the beds but:eventually thrusted the

Paleozoic limestones over the Lower Cretaceous strata. The Crest Line

thrust fault and the structures related to.it are examples of this type*

The later faults caused by tension, are of the Basin and Range type*

The best example is the normal fault which outlines the base of the Hua­

chuca Mountains on its eastern aid northern sides*. ..

Huachuca Canyon fault> The Huachuca Canyon fault in the bottom of

Huachuca Canyon is probably responsible for the location and the straight

character of this;drainage* The fault trends north 40 degrees east and

has offset the Bolea quartzite about 1300 feet stratigraphically* The • -

northwest block is down thrown. It. does not offset the Crest Line thrust

fault or the Cretaceous beds west of the Crest Line thrust fault. This

suggests that the Huachuca fault may be pre-Crest Line thrust faulting

32^ Feth, J,H* The geology of the Northern. Canalo Hills, Santa Crus County, Arizona: Library University of Arizona, Ph.D. thesis, 1947, pp. 121-122* •45

and also pre^retaceous, such as the Dividend fault in Bisbeo. It is

equally probable that the over riding Paleozoic formations on the Crest

Line fault moved as blocks, being separated by tear faults, and not as a continuous sheet* ■

The Crest Line thrust fault: The Crest Line thrust fault is the major structure running through the central portion of the range. It is roll exposed along the slopes of Huachuca Peak and in Garden Canyon (see

Plates 9# 26, and 27)„ Following the northwest trend of the- range, it extends from the Manila Mine area in the northwest corner of the range through Garden Canyon, continuing five miles southeast of Garden Canyon, 33 where it has been mapped by R. H* Weber * The fault is therefore at least

13 miles long* ' • ' ■ - ■■ - ,• " -- ' ■ - - - - - ' -

The fault plane dips to the northeast about 45 degrees in Huachuca,

McClure and Garden Canyons. In the Manila Mine area it dips to the north at an angle less than ten degrees* In the southern part of the range*

Weber states that the fault dips from 0 to 30 degrees to the"oast*

The displacement along this fault is unknown, because the'original * f- average dip of the fault surface has not been determined. The stratigraphic throw exceeds 5>000 feet in Huachuca and Garden Canyons and is over 13,000 feet in the Manila Mine- area* Net slip would be" larger than the strati­ graphic throw and•would depend on the - dip of the fault plane* By using " ' or the trigometric relation described by Billings'73, assuming" dips of- the -35 *3433

33 Weber, R*H« "personal communication, 1943*

34 Weber, R.H* personal communication, 1949• • ■

35 Billings, M*P* Structural geology: New York, Prentice-Hall, Inc* 1942, p. 178. fault plane and using 13,000 feet as.the stratigraphic throw, the following net slips were calculated;

Dip of fault plane : "Net slip on the thrust *

' •■'■■■■' ' 10° - ■ - 14»7 niles - - - -

- - - '■ ■' - ■- 20° -- ..." "' ' ' 7*4 Biles '- -- "— ,

' ■ - 30° : : 5.0 miles

": ’ ^ 3.9 miles

•The folding caused by drag along the fault plane shows that move­ ment of the hanging wall came from the northeast, as indicated in the

Manila Mine area, and along the slopes of Huachuca Peak (see Plates 9, •

26, and 27) • - , - - V. y ^1: ••

Part of the fault zone is marked ly a limestone breccia up to 250 feet thick. The limestone cobbles and pebbles were derived from the •

Paleozoic formations a M are rounded to subrounded. The breccia also •- show shearing and stretching of the pebbles. Thb shape of the fragments suggests that they were derived from the erosion of the exposed Paleozoic formations of the advancing thrust sheet which later overran them, causing the shearing. The limestone breccia capping.the ridge to the east and south of Woodyard Canyon lies relatively horizontal on the overturned. -

Lower Cretaceous strata* If the limestone breccia is a fanglomerate derived from the advancing thrust plate then the Lower Cretaceous strata would have had to be eroded subsequent to their folding in Laramide time and prior to the deposition of the fanglomerate and -the thrust faulting. : . _ . . ■

It is also possible that the breccia is drag from the Lower Cretaceous limestone conglomerate formation. This is suggested by the fact that the breccia lies next to the Permian strata in the Manila Mine area. Geologic sections: of:’this area X i ^ t e 2) shciw t4mt.1±ds-.intei*pretatic«f.is reason-

1able* : 'ii- -T-- * A" \ , ‘"•is r ' l d ,':5v

.. . The evidence for thrusting in the Manila Mine area is quite definite.

An outlier (klippe):of limestone (presumably Paleozoic) lies a feir hundred

yards east of the Pyeatt ranch: buildings. It is surrounded on all sides

:by Cretaceous beds. That the Cretaceous.beds underlie the Paleozoic- is

shown by the.deep reentrants of Cretaceous in the drainage cutting through

them,. The; Cretaceous shales below the Paleozoic have been rolled up into

forms. resembling logs by the thrust* The: springs .at the.-, northern end .of

the thrust outcrop show.that the dip of;the-thrust plane is-to the north.

The water feeding these springs -follows the dip of the fault;plane flow-:

ing top pf - the impervious Cretaceous beds, :-,n : , 1:

^ B a s i n Bange fault : The Basin Range* fault - outlines the northern and

eastern flanks of the Huachuea Mountains in; the area: mapped, ; It, extends

from, an , uritopwn point west of . the Pyeatt Ranch buildings - east along the

northern edge of the range and then southeast, along the. east .side- of: the

range to Gold,Hill, where it.is.last exposed.

The Basin Range, fault is a normal fault, dipping about 45; degcees,

away from the range. The foot wall is pre-Cambrian granite esobept west.

of the: Manila Mine area, where the foot wall is Cretaceous rocks, ; The

hanging.wall on the north^side of the range, consists;of Tertiary opn-: ,;

glomerate and gravels, _ On.the east side, part of the hanging wall is;

made up of red fine-grained sandstones, siltstones, and buff fine-grained:

sandstones, which may be Cretaceous, but most of thorhanging-wall here.

also consists of Tertiary conglomerates and gravels,

‘v " The; Ba sin- Range rfault: it self is displaced normally' in the vicinity of Fort Huachuca by a fault-with a northeast trend and a displacement of a few hundred feet* There may be others of this type which have not been mapped.

In the southern part of the range, the Basin Range fault is not 36 exposed * It is, however, reasonable to extend it farther southeast along the front of the range on the basis of information obtained from wells. As shown on Plate 4, the ground water level drops rapidly east of the Basin Range fault. This is caused by the difference in rock types on the foot wall and hanging wall of the fault. The foot wall is granite and relatively impervious, while the hanging wall is largely made of Ter­ tiary conglomerates and gravels which are relatively pervious. Therefore the water upon striking the fault sinks rapidly in the Tertiary conglom­ erates and gravels, and the water table is consequently deeper.

As shown on Plate 4, the rapid drop off on the water table in the southern part of the range occurs just east of the projection of the Basin

Range fault into that area. The writer concludes that the fault continues to the southern end of the range.

Lyle Peak faults The Lyle Peak fault can be followed from a point near the crest of the range at the head of Huachuca Canyon southeast for five miles to the head of Garden Canyon. It continues southeast off the area mapped for an unknown distance. The fault follows the axis of the

Rough Canyon anticline* In its present attitude, it is a normal fault dipping 76 degrees to the northeast in Garden Canyon* Fault grooves found southeast of Garden Canyon show dip slip movement* The hanging wall is

36. Weber, R*H. personal communication, 1949. -49**

Lower Cretaceous strata, and the foot wall Is Permian limestone*. Because the Lower Cretaceous limestone conglomerate formation occurs.on the.hang- ing wall of the fault. In McClure Canyon, it is possible to make an estimate of. the stratigraphic throw, which is from two to three thousand feet*

The age of the Lyle Canyon fault is not definitely known. It is believed by the writer that it is due to tensional forces, which would classify it with the late Tertiary Basin Range fault* The close relation with the axis of the Rough Canyon anticline is interpreted as meaning that the axis of the fold was a zone of weakness and that the position of the fault was determined by it* It is possible, however, that the fault is contemporaneous with the formation of the anticline, which would mean that the displacement along the fault died out by the time the struc­ ture approach®! the Lower Cretaceous limestone formation, which in this area is about 10,000 feet stratigraphically above the Permian*

...... Lone Mountain Fault Structure

Lone Mountain lies outside of the area mapped and was studied only at its southern end. The structural relations"shown probably have a direct bearing on the relationship of the Cretaceous and the Tertiary volcanics mapped (Plate 1), and it is, therefore, included* Where observed. Lone Mountain is made up of volcanic agglomerates, largely derived from the Tertiary volcanic flows* The agglomerates dip from

10 to 35 degrees to the southwest* On either side of the agglomerates are Cretaceous beds in fault contact with them. The fault on the east

side was not well exposed but appears to be steep* On the west the fault dips 60 degrees to the southwest* The Cretaceous beds make the -50-

hanging wall of this reverse fault# On "either side of this down dropped block (gi%ben) the Cretaceous beds dip about 70 degrees to the southwest.

The contact between the Cretaceous strata and the Tertiary volcanics in the area napped (Plate 1) was not observed. The structure of Lone

Mountain suggests that it may be a fault contact#

Structural History

Pre-Lararaide Structures

The structures shown on the geologic map (Plate l) and the cross-

sections which accompany it (Plate 2) are either of Laramide age or later. Stratigraphic evidence indicates that strong structural breaks occurred prior to the deposition of. the Middle Cambrian Bolsa quarts!te, during the interval between the deposition of the Permian limestones and the basal limestone conglomerate of the Lower Cretaceous, and that some diastrophism occurred in Cretaceous time.

Post Permian Pre-Cretaceous structures: The basal limestone con­

glomerate of the Lower Cretaceous overlaps Paleozoic and even the pre-

Cambrian rocks in southern Arizona and Hew Mexico. The unconformity is

both erosional and structural. In the Huachuca Mountains a pre-Cretace-

ous valley 2500 feet deep has-been cut out.in.the.Permian limestone, .

In the Bisbee quadrangle"5 , the pre-Cretaceous Dividend fault has a

-throw of 2,OCX) to 5,000 feet. Erosion subsequently stripped almost all 37

37, Butler, B.S., et, al.. Some Arizona ore deposits: Ariz. Bureau of Mines, Geol, Series, No, 12, Bull, No, 145 Oct. 1932, pp. 32-33* -51-

of th©’ Paleosoic rocks ' ftom the %JthrOwh gide of the Ditidenf ‘'fifllt, exposing the pre-Cambrian Pinal schist« In the Lead Mountain area*'0 of the southern part of the Sajrflre Arisosa^ aiwtfmr pro-

Cretaceous -fault M e been • mapped, - The /Hmchuea Canyon fault may also ;■ 1 '? • r.!:' :: v .... - ' : ; - bo of this age* ' : " r. •■■■/' v:; - r-:. ; : : ; ■. ' w- '1^:: ; i-': ■: .vZm ;- . L::": The age of these structures Is not definitely known, A e dlstrl- - r.-xv:;-.;;-: vi.r., ' ■ v.. r : ^ '• - / ' - button and character of the Triassic and Jurassic rocks of Sonora and northern Aid zona suggest that mountains were present in southern Arizona during the late Tri&ssic and early Juraesio and that they were tha source of the material in these rocks.

In regard to Sonora/ Xing‘S believes that the Bar ranee basin mist - have covered horthea stern • Sonora at some point n^u* or south of > • -

Nacozazd, extending thence southeastward across western Chihuahua, The -■

Mrrahca formtion hear* this-"supposed 'northeastern margin of the basin consists wholly of Upper Triassic end Lower Jurassic continental deposits.

Toward! the west: a»i south, marine 'sjeabers become intercalated *in Increas­ ing proportion. The source of the sediments for this formation would# therefore,: be to the north and east,. • ’ > -• -• . • ' - : - .

■i M c K e e ^ suggests a land mass to the routhweSt as the source of the 403839

38 Alexis, C,0,,' % e geology of the M a d Mountain area, Pima Comity, :- Arizona* Library Univ* of Arizona, Master* s Thesis, 1939# p.

39 King, R, E., Geological reconnaissance in northern Sierra Eadre Occidental of Mexico: Geoli’ Soc# Am, Bull* vol, 50, p?* 16^-1659,

40 McKee, E«D,, Triassic pebbles in northern Arizona containing invertebrate fossils: Am, Jour, Sci,, 5th series, vol, 33, 1937, p* 261, r.''; i v.'., : :: : • 'y V V.. ^ '• y y

■. :yyv- - V.y“Lv::-"'i ■ r;:' - r , - 5 *

Upper Trlassie eedimentsula northern Arizona. HI#, evidence is as ■PF-'-- follows:

"Invertebrate fossils of Permian age have been; found in a- of the rounded pebbles occurring at various horizons and locali­ ties in the Upper Triassic deposits of northern Arizona. Recent examination of these fossils has indicated that they are all of species typical of the marine.facies of the Kaibab limestone which occurs to the west and southwest, thus suggesting that the pebbles were derived from a land mass in that direction ... General increase in average size of pebbles toward the south­ west and a definite decrease in limestone beds within the for­ mation in that direction, tend to substantiate the theory [advanced on the basis of fossUs.* ; . —

The extent and character of this mid-Mesoseic diastrophism is not known* • V. c

; Cretaceous structures: During the deposition of the. Lower Cretaceous beds in the Huachucas, there was apparently little folding* The beds from the top of the basal limestone conglomerate through the entire Cretaceous

section exposed; here do not show singular unconformities. The major fold­

ing, therefore, came sometime after the deposition of these b e d s . T b a t

there was some structural movement duripg this period is suggested by (1)

the presence of ▼olcanio flows in the section, (2): the p-eat tMeiaiess of

the section (over 15,000 feet) would require subsidence, and a source

sufficient to furnish sediments in such volumethat sedimentation would

keep up with the subsidence, since the beds are largely of shallow near

shore origin, (3) a conglomerate of volcanic material,found in the Sunny-

side beds in Bear Canyon, and (4) the conglomerates in the Scotia beds,

which are largely of volcanic origin but also eontain -pebbles of Paleozoic

(?) limestone.

At the northern edge of Sonora in the Cabullonevdistrict,Taliaferro

T. '•re. ^^ ^ y . . ■v. • <• r ______41 In King, R. E., Geological.reconnaissance in northern Sierra Madre Occidental of Mexico: Geol. Soc. Am. Bull., vol. ^), Nov. 1939, P» 1714* -53-

has found evldence of considerable disturbance between Lower and Upper

Cretaceous time. : ia unconformity between the Lower and Upper Cretaceous may account for the thick development of the Lower Cretaceous in this region and its apparent absence at nearby local!ties, where Upper Cre­ taceous beds overlkp still elder rocks. : • v ■: w.- . V: x -v-^Uv r i . r . v . ; • i x ' . i v : x7 : . J. VI"':: \ .'t -v:x o f - V t 1 ;..V' . . x;" i:: x.-: r x 'icx .x:t V : ~ Am 44mg :i

At the close of Cretaceous time, tiie Rocky Mountain region was -L'-v x'1 r ; :f x'. thrown into a series of mountains by the Laraaide revolution. Folding x x v /U, .,v x ; r; v .--.iv'^-."y }r. v;x : !‘Ax ’x ■ and thrust faulting occurred on a large scale. Much of the folding • 'I 9• ' ' * * '■ « *I* • ‘r** f ,• '• " ♦ '*4 ; i.' : '• *•• ^ •\ S• ■ •• •!- • . " ‘ •' : . S %- •>"'r < V " ' . » - shown in the Huachuca Mountains probably occurred at this time.

The Laraaide folding was intense, as is shown by the near vertical An .■ .yf A*; -, V \ --:nn: .O.y .n- ny n-nn- '-n- x : v x nxnn:. . attitude of the Cretaceous beds on the west side of the range in Parker IA nx-- x'i:;'inri.r. x- {'X/.A) ' v.) I A n . lit Canyon. That the principal folding of the Cretaceous beds was completed v.n: vAn: t.:n nnI n - : -xn tn-nn - r; t . . r- -f,t: n - nn.:: ' nnn:

dip recorded is 40 degrees. Unfortunately, the stratigraphic contact between the Cretaceous strata and the Tertiary volcanic# was not found nil; ' nto.y. : -..v.:: c11- x I I - : y.-v.-y-ntn:.. in this area. As suggested under Lone Mountain Fault Structure, the

J . ; , : i ^ ' 4 ^ ^ * r r- . . . „ . . x- - ' - - » - - ■ -r r ■' '*- " * * . ' ^ ^ < j contact may be on a fault. The Tertiary volcanics and Cretaceous h a w , -■ -x I X ■ .... . : I « - ri "* .: * -- :' x . ■ "yx--* ' V- A- - ’ ; , . > x however, been observed elsewhere in this general area. This information • is summarised by lmlay as follows*

„ - .“All available evidence indicates.that the principal folding of the - Cretaceous rocks of northeastern Sonora and adjacent parte of Aris­ ons. occurred during the Laramide revolution and ims completed

a! Ay'..... y ;’y . .--.y ' yr x. I.?-.. ■'•••'.x x y .'- 'i ' x x c

A2 Inlay, R. W., Paleographic studies in northeastern Sonora: Geol. Soc. Am. Bull., vol. 50, Nov. 1939, p. 1728. - -54-

_ - . _ _ _ _ / ' - before Tertiary-vuloanlsm began. In Camon Santa R o m n ^ r II ..., Tigre, the writer noted that the Cretaceous and upper Paleozoic foraationsarestrbnglyoTertumed toward the west and are bver- . lain by several thousand feet of nearly flat-lying lavas whose lower part fills the irregularities of a ragged erosion surface. Similar relations between the Mesozoic sedimentary rocks and Tertiary volcanic rocks wore ‘rioted by King (1939) In the Chihua­ hua plateau east of central Sonora. In the Bisbee district at • least part of the strong folding of the Cretaceous formations ‘ occurred at the end of the Cretaceous or in early Tertiary time (Tenney,1932, p. 49). South of the international boundary in the region east of Caballona, volcanic rocks rest on the eroded , edges of strongly folded Cretaceous rocks.* r ; -

Post-Laramide Structures l vr-1 ■ "r r 'T; i v j V' .vX" . ’ The writer believes that the principal way in which the rocks V O-; i h;- i .:.n pv" \ V-; '.p "*r>: V/: - yielded during the Tertiary to compression was by thrust faulting.

Some folding may have occurred, but this only in the fore of broad warp- «■*:. f . • ^ , * • . « V 1 i - ' •• - . . . « • »' - s - • ■. ' ■ t »•" r ■* -:•» * •• ing of the crust or as the result of drag near the thrust planes.

It has already been indicated (p. 46 ) that the Crest Line fault in

the Manila Mine area has thrust Paleozoic beds over folded Cretaceous ;

beds «id tiiat, $nrior to thrusting, these fblded beds had been eroded. ''.",V:v t b 'T-'.r. ' r,i ; v-r," t'- The age relations between the tlmisting and the Tertiary TOlcanics are

not shown in the area mapped but can be observed in the Northern Canelo

Hills about fourteen miles west of the Huachuca Mountains. * ' ' „ v - ' ■ r - 1 ", - . .. t : f J, r ; ' p * '■ ' t » - -v •» - * ^ .*-< <■—

Feth4*' has mapped Permian limmtones thrust o v m t Trotlary (?) / / volcanics. Wilson has found thrusting over the Pliocene (?) Pantano 43*

43 Feth, J.H., The geology of Northern Canelo Hills, Santa Cruz County, Arizona: Univ. of Ariz., Ph.D. thesis, 1947, pp. 109-U4* ‘

' . " •44 Wilson, E. D., % e basin aori- iva^e province in Arlzbria: t a ^ M L l d w d manuscript,Ari*.Bur.of Mines files.'1^; ^ ’ - -55-

lie about 25 miles northeast of the Hwtiraoas, G i U u l i y ^ places the thrusting as post Tertiary (?) volcanics. He also states that the principal deformation in this range was Tertiary (?) thrusting*

In his paper on the Uncle Sam Porphyry of the Tombstone district,

Gillully^ has postulated two periods of thrusting, the one younger and ’

the other older than the Bronco volcanics. The Bronco volcanics lie unconformably on the Lower Cretaceous and are either Cretaceous or early

Tertiary in age* The U n d e Sam porphyry was intruded into the later

thrust fault zone, probably during the early Tertiary. Lying unconform­ ably on the Uncle Sam porphyry is the Gila conglomerate of Pliocene age*

The Tertiary structural history of the parallel valleys and ranges

of southern Sonora is similar to that in the Huachuca Mountains. King* writes as follows:

"After the early Tertiary eruptions there was further mountain making ... Farther west, as in the province of parallel ranges and valleys, the mid-Tertiary deformation apparently equals or exceeds the ear­ lier, post-Cretaceous movement, and it was probably at this time that the mountains begain to assume their present form. At any rate, the early Tertiary volcanic rocks are generally unconform— able below the later Tertiary Baucarit formation and that formation seems to have been deposited in intermontane basins which had nearly the same positions and outlines as the prerant longitudinal valleys ... At the close of Baucarit time, there was renewed erogenic activity ...The baucarit formation mas tilted and thrown into low folds. North of the 28th parallel, the rocks of each of the high

45. Gillully, James, Thrust faulting in the Dragoon Mountains, Arizona (abstract): Geol. Soc. Am. Bull., vol. 52, no. 12, pt. 2, Dee. 1949, P» 1949*

46. Gillully, James, Emplacement of the Uncle Sam Porphyry, Tombstone district, Arizona: Am. Jour Sc., vol. 243, no* 12, Deo. 1945,pp*643-666e 47

47. King, R. E., Geological reconnaissance in northern Sierra Kadre Occidental of Mexico: Geol. Soc. Am. Bull., vol. 50, Nov. 1939, pp. 1715-1716. „ ,: \ - : - v.:\ \ -56-

raountain ranges, from the Great of the Sierra Madre westward into Central Sonora were pushed to the west on overthrust faults, . which partly overrode the Baucarit formation lying in the valleys' next to the west*"

Sometime during the late Tertiary, perhaps in the Pliocene time, tensional forces became active* The result was the normal faulting which has outlined the limits of the present day ranges* The Basin

Range fault on the northern and eastern flanks of the Huachuca Moun­ tains is an example. :

The Basin Range fault plane has been offset by faults of a few hundred feet displacement, :

The latest events in the geological history of this area will be

considered in the chapter on physiographic history*

PHYSIOGRAPHIC HISTORY

The physiographic history of the San Pedro Valley has been des­

cribed by Kirk Bryari^®• A summary of his conclusions is presented *

here, followed by observations made in and near the Huachuca Mountains

by the writer* . • ■: : r

Bryan! s views follow* The mountains of the San Pedro Valley

Region in southern Arizona are the residual elevations resulting from

an uplift that involved the Gila conglomerate* * The Gila conglomerate

is a valley fill now deformed and dissected, but accumulated under arid

conditions in enclosed or partly enclosed valleys* Late Pliocene verte-

48, Bryan, Kirk, San Pedro valley, Arizona, and the geographic cycle, (abstract). Bull, G,S,A., Vol, 37, No. 1, March 1926, pp. 169-170. 57-

brate remains were found in the fine-grained equivalent of this con­

glomerate In localities between Benson and Tombstone.

Gidley^ writes the following in regard to the fine-grained - y

equivalent of the Gila conglomerates

"The stratified beds of these localities consist principally of red days, sands, ami soft limestones that were evidently laid down in salt lakes of small extent in the central part of the Pliocene basin. The bones occur for the most part in relatively small patches or layers of greenish tuffaoeous d a y , which, according to Bryan, interfinger on one side with arkosic gravel and conglomerate typical of deposition on alluvial slopes and on the other with lake beds. This position seems to confirm : Bryan’s view that these bone-bearing patches of greenish shale represent the marginal and fresh water springs that are charac­ teristic of the borders of salt lakes in such basins. The i localities thus probably constituted the chief watering places for the animals of the region, and here naturally occur their fossil remains."

Since Bryan found these vertebrate remains near the top of the for­

mation, he concluded that the deposition of the Gila conglomerate was

completed by the end of Pliocene time, and that the uplift is subse­

quent but not necessarily much later. He goes on to say that*

"The deformed Gila conglomerate everywhere rests unconfonaably on older rooks, including the Tertiary lavas. The nature of the deformation which produced the basins is not known, but it is certain that the mountains of that time were detached ranges located essentially but not precisely in the position of the present mountains ... The post-Gila uplift of the mountains is of the fault block type ... The blocks were pushed through the less competent Gila causing minute faulting end crumpling of the formation*.

The last statement made by Bryan merits special comment. The Gila

4 f Gidlay, Fossil cprobbscidea and (edentata o f the San Pedrb 'Valley, Arizona: U.S. Geol. Surv. Prof. Paper UO-B, Jan. 1926, p. 84.

V: V': ."'.vy-V::' -58'

conglomerate did not cover the entire region before block faulting occurred, because the conglomerate is of local origin and therefore the source of the material making up the conglomerate must of necessity have been left exposed. That the Huachuca Mountains were a source of r supply and were never completely covered by the Gila conglomerate is shown by its character near them. The formation as exposed near the ■ - northern end of the range (hanging wall side of the Basin Range fault) is extremely coarse and poorly sorted (see Plates 23 and 24), but as - it is followed north and west, the material becomes finer, finally grad­ ing into sandstones, silt stones, and limy clays hear Elgin (see Plate

25). This suggests that the area to the south and east (the Huachuca

Mountains) was the source of the material in this formation.

Bryan1 s views on the post block-faulting history of the region are ; « as follows* A long continued period of erosion formed a widespread sur­ face, the Tombstone pediment. Before this cycle was completed, the streams began to cut down to form a lower pediment, the Whetstone pediment. This second cycle was also interrupted by the incision of the streams to form the Ar&vaipa terrace. The valleys of the present streams lie below this terrace. - ' ' "■■■ - ' ' - - ‘ ;

The physiographic history of the Huachuc&s appears to follow the pattern outlined by Bryan. The Gila conglomerate (?) exposed north of the range is folded and/or faulted. The writer does not believe that all of the deformation of the Gila was caused by block faulting, because the beds of Gila conglomerate in Sycamore Canyon are approximately at right angles to and are cut off by the Basin Range fault. This suggests that post-Gila thrust faulting may have been responsible for the disturbed - 59-

Batura of the con*lo«I,t.. . - VOL: :er Following the ULook-faultlng along the Baeln Range fault, erosion

formed a pediment around the range. This pediment was cut on the tilted

Gila conglomerate and the pre-Cambrian granite. The pediment creeses the

Basin Range fault without a marked topographic break to indicate that the pre-Cambrian granite is more resistant to erosion than the semt-consolidat-

ed Gila conglomerate. This indicates that the period of erosion was

sufficiently long so that the course of the streams was no longer controll­

ed hy the underlying rock. . , , , , :

; ; . Sufficient regional work has not been done to correlate the pediment

developed around the Huachuoas with those described by Bryan. Hence this

pediment will be referred to as. the Huachuca pediment. Following the

development of the Huachuca pediment, regional uplift rejuvenated erosion,

so that the pediment is now being dissected. . , ; ^ .

An interesting feature of this dissection is the capture of. several

north northeast flowing streams lying between Huachuca Wash and Sycamore

Gulch by Sycamore Canyon. Plate 6 shows the location of the streams and valleys involved. Similarity of names may cause some confusion. For

example. Sycamore Gulch is a tributary of the Bobooomari River, while

Sycamore Canyon is a tributary of Sycamore Gulch. A tributary of the

Bobocomari River drains Huachuca Canyon. Therefore when Huachuca Wash

is used, the stream on the pediment is referred to, and when Huachuca

Canyon is used, the stream in the mountains proper Is meant.

The streams beheaded by Sycamore Canyon are tributaries of the Bobo­

comari River lying between Huachuca Wash and Sycamore Gulch. Evidence

that these streams once drained part of the area immediately west of ' -60-

Sycamre Gazynon is the wind gap which ia w e t ©f the point where the Canelo Road croesee Sycamore CaDyoh.’ '’The' w ^ ^ :'dbrain^vly,"thi8 beheaded stream has gently sleplng Md##, a M the stream channel itself has banks with a mocimum height of three feet; In many places banks are' so low that a ear can easily be driwem a o M s s the etr^uh bed. In contrast to this Sycamofe Canyon (the beheading stream) ha# steep aides with banks from 20 to 30 feet high along the channel. Where the canyon traverses the Basin Range faiiit, it M s ctit a narrow g o f ^ about 100 feet long in the pre-Cambrian granite footwall. The stream drops about 40 feet in this gorge. Both above and below it^ the gradient is mmch lose, (see

Plates 28 and 29)•

A branch of Sycamore Canyon is advancing into the drainage of

Blacktail Canyon, and it has captnrW a portion of the west drainage of that stream. It is expected that eventually the entire drainage of

Blacktail Canyon will be directed into Sycamore Canyon, just as was done with the streams betweem Hlaektail Wash and Sycamore Gulch.

The development of stream piracy is closely associated with the history of the Bobocomari River. The average gradient of this stream is about 35 feet per mile from Elgin to where it enters the San Pedro

River, except along the proj ection of the trend of the Mustang Mountains across the stream, where the gradient is about 60 feet per mile. These gradients suggest a ridge between the Mustang Mountains and the Huachuoa

Mountains which at one time separated the Sonoita and the San Pedro

Valley basins. The semi-consolidated Gila conglomerate (?) probably thickens on either side of this ridge toward the-©enter of the basins.

As the Bobocomari River eroded headward toward the Sonoita Basin, -61-

it was held up by the ridge. During this time the drainage pattern that developed between the Huachucae ard the Bobocomari River was one of north northeast trend. Upon breaking through the ridge, the Bobo- comari River started to erode the semi-consolidated Gila conglomerate

(?) in the Sonoita Basin. Headward erosion proceeded:rapidly, enlarging the drainage;area of the river from 185 to 330 square miles. The first tributary of the Boboeomittl M v e r on the west side of the ridge and from the southwest is Sycamore Gulch, which drains about 40 square miles, including the northwest portion of the Huachuca Mountains.

The piracy of drainage in this area has caused the drainage from the captured basins to flow a longer distance than before capture. For example, the drainage from the west side of HLacktail Canyon captured by Sycamore Canyon now has to flow 10 miles in order to reach the same point (the outlet of Bl&cktail Wash) which it formerly reached by flow­ ing 6^- miles down Blackball Wash.

Despite the longer route Sycamore Canyon is the beheading stream, because its gradient is steeper than that of Blackball Wash. This is caused by the low gradient along the Bobocomari River and Sycamore Gulch, as shown in the following data* : : .

Distance ^ Difference in Average (in miles) Elevation to^ient (in feet) . (feet per mile)

Outlet of Huachuca Wash to .. :v - . outlet of Sycamore Canyon 6 5L0 51,6 (A to C) - - L

Outlet of Sycamore Canyon to B in Huachuca Canyon 4 660 165,0 (C to B) . . / : " ' ' . " . Total 10 970 Distance ; Difference in Average (in miles) Elevation Gradient (in feet) (feet per mile)

Outlet of Huachuca !7ash to : . B in Hmehuca Canyon 970 149*2 (A toB) - :■ ! :: y i ■- iV.^r

Both Sycamore Canyon and Huachuca Wash have steeper gradients as the mountains are approached. Using the distances between B and where

the 5000 foot contour outs these streams, the following;gradients were

^computed: ;. - . i-.-.x /

Distance Difference in Average (in miles) Elevation Gradient (in feet) (feet per mile)

Sycamore Canyon 1.25 300 240

Huachuca Wash " i V- , v.;1.5. : 300;,,;,,,.; ■200 _

• ' ' ' In both oases Sycamore Canyon M s the steeper gradient. The

actual gradient of Sycamore Canyon is steeper, because the distances

used were to point B in Huachuca Canyon. . ; > >

The lower gradient shown in the Bobocomari River and Sycamore Gulch

in the above data results from this portion lying at the baud of the

drainage of the Sonoita Basin. This drainage area is 145 square miles.

The flow is therefore sufficient to remove the sediments brought down

by Sycamore Canyon, thus maintaining the steep gradient of that stream.

The steepest gradient on the Bobocomari River east of Elgin is

near its junction with the San Pedro River. As erosion moves this

gradient headward, the tributary streams along its course will be

rejuvenated in turn. .: ■

For the future, we have in this area conditions for continued

deepening of the gulches and canyons, the eventual destruction of the

Huachuca pediment, and the formation of a lower pediment surface. o r e i m m a s

Mining In the Huachuca Mountains has been carried on in a small way since the 1880*8 except in the Fort Huachuca Military Reservation area, which has been closed to prospecting and mining operations• Most of the mining has been done in the southern part of the range. Mining operations in the northern part of the Huachucas, west of the Military

Reservation, have been on a very small scale. During the past twenty years they have been almost negligible.

Hartford District (Huachuca Mountains) GochiseCo. 1907-194750 51 , _ . v;;.v < Gold Silver Lead Copper Zinc Lode Placer ;:V,Y

380.75 oa. 109.58 osi 22,948 oa. 487,185 1 W . 71,250 lbs. 348,000 lbs.

i $15,495.00 $15,335.00 $36,462.00 $10,048^0 $39,247.00

m:-': Total : $116,587.00 Vvv '-Y :

Huachuca District, Cochise Co. . 1900-1934 ' ''

Copper Glance Mine 300,000 lbs. Cm, $4,000 An, $50,000 Ag

Y Total value $100,000 ' : U-'.;.: • Y- :

Eureka Mine 470,000 lbs. Pb. Total value $15,000

50 Statistics from Aria* Bur. of Mines, Dniv. of Aria., Tucscm

51 Rising, M.J., and Heineman, R^.S., Arizona Metal production: Aria. Bur. of Mines, Dniv. of Aria., Bull. 140, p. 91, 1936. In the irrltar's opinloay tho data given in the aeocod tabie

(1900-1934) are unreliable. First, the silver production should be associated with: the lead production of the Eureka Mine. 1 Second, the minerals found on the dump of the Eureka Mine are copper minerals and not lead. Third, the known producers of lead.are not listed. They are the Manila or Panama Mine and the Cave Greek (?) Mine. The latter is located in the southern part of the range. : :: . v:;:ivh -Liv; : / V'‘ Vr"-. V' .. - ' , • Panama Mine

: /The Panama Mine, the largest in the area mapped, is in the mctreme northwest-portion of the range, just east of the Military Reservation boundary fence and one half mile south of the Canelo-Fort Huachuca Road.

The discovery date of the mine is not known. It was certainly later than the fomriing of Fort Huachuca in 1877 because the area was not safe from the Apache ^Indians before that time. The mine is located on; the

U. S. Geological Survey topographic map which: was published in 1904#

; r: During, the 1920* a a small mill operated on the ores from the :, • property. The mine workings were apparently never deep. later, wee encountered.125;feet below tiie surface in the main shaft, and pumping was required. The pumping was stopped by court injunction on June 9,

1928, because the spring on the Pyeatt Ranch ran dry allegedly as the result of the pumping operations.

Sometime after the court injunction had been issued, a re survey •„ of the reservation found that the mine was. two hundred yards within . - the Military Reservation.The operators were then obliged to move their equipment from the property and cease all operations. ... - 65-

fhe major structure In the Panama Mine area is the Crest Line

fault, which has thrust Paleozoic limestones over Lower Cretaceous •

strata, mostly red shales and sandstone# The fault surface dips to

the north less than ten degrees. The overthrust plate of Paleozoic

limestone has largely been removed by erosion, so that the overthrust block is less than 100 feet thick. :

The mineralization is on'a steeply dipping northeast flitmre which cuts the Paleozoic limestones and the Cretaceous strata below

the thrust fault surface* Specimens of ore collected, from the adit

level consisted of oerussite in a quartz and ealcite gangue with a

little malachite* Except for the adit level, the mine was not access­

ible for study* t % /. ■

Joe Bailey Prospect

The Joe Bailey prospect is located cm Brushy Canyon between the

McDaniel two story adobe house and the Wills Camp* The country rock

is Cretaceous red shale. A little malachite and chalcbcite in a quart

gangue were found on the dump* Water was encountered within 100 feet of

the surface. The size of the dumps indicates that the workings are very

limited in extent. r';': ‘

Sunnyside Mining Area

The "ghost town" of Sunnyside lies in the center and on the west

side of the Huachuca Mountains. It can be reached by driving two miles

from the Montezuma Pase-Canelo Road up Copper Glance Canyon* -66-

The Eureka and the Copper Glance mines lie farther up Copper

Glance Canyon. These mines were operated about the turn of # e e#atury by a small religious sect living in Sunnyside* Specimens containing native copper and reported to resemble the copper ©ree In the Keeiree- nawan lavas of northern Michigan are said to outcrop in Copper Glance

Canyon5 . A large slab of native copper from the Huachuca Mountains is on exhibit in the mineralogy museum of the University of Arizona*

It may have come from Copper Glance Canyon* Copper carbonate showings are reported ffom a. group of claims near the Sylvania Ranch.

Fort Huachuca Military Reservation

- Numerous stories have been told about the richness and the large amount of ore to be found on the Military Reservation, especially with reference to gold. Skepticism regarding the validity of these stories is eoBBon* " vV' - ‘ : -v ; '

• During the course of the field work not one specimen of mineralized float was found in the canons and washes, and only a few outcrops show­ ing mineralization were seen*

On the east side of the ridge west of Sycamore Canyon, a veinlet of galena one eighth inch thick was found in the Abrigo formation* 0m the north side of Huachuca Canyon, several c&lcite stringers less tiMm one inch thick, containing copper carbonate, were found in the Devonian

53 Private engineering report* Martin liiaeatone noar the Crest Llne fault, , . ^ '

Fluorite veins less than one inch thick were found in^the pre-,

Cambriem granite north of the north gate to Fort Huachuca. Fluorite and lead minerals are reported from Blackball Canyon but have not been found by the writer. , : ^ ' , .. • 4- - ■ -j • - - '■■■*- • • i - . - ■ , ' - i! »* * * ■. •

V; WATER SUPPLY - ..:V , ,V

'] , , r.-- \..L : J. .1 C" i'i :. v: " . ' '■

The Huachuca Mountains because of their greater height receive more rainfall than most ranges in southeastern Arizona. This relative abundance of water was in part responsible for the establishment of :

Fort Huachuca there in 1881. Until the outbreak of World War II, the .

Fort received. all of its simply from springs and shallow wells in •v* - Garden, McClure, and Huachuca Canyons. The expansion of the Fort . during.World War II created a demand for a larger and more dependable source of water. On the recommendation of the ground water division of the U. S. Geological Survey, deep wells were. sunk in the valley fill wist of the range. r, c

... Tombstone, Arizona, also received its water from the Huachucas.

Its source was in the springs and shallow wells located in the canyons • ...... - '• ■ * - . . . » • ’• •• • - - ' ' * • • • •• • south... of • . t the • Fort Huachuca . ■ ■ Military • ' Reservation. •• ' - • * ' • Tombstone ' was ' drill- - ing for water within its city limits during 1947. The success of this program is not known to the writer...... , . ,

The water supply la the northern part of the Huachuca Mountain can be classified into two groins s the deep wells and the shallow wells or

springs. >L: UT : \ ' v* . >. -68-

The deep wells are located north and east of the Basin Range fault and are drilled into the valley fill. The water table drops rapidly just east and north of the Basin Range fault because of the relative pervious­ ness of the fill. Farther east the water table slopes gently toward the

San Pedro River. Plate 4 shows the nature of this drop off by contour lines, drawn on the elevation of the water table. The reader who wishes further information is referred to the offices of the ground water divis­ ion of the TJ. S, Geological Survey in Tucson, Arizona.

The shallow wells and springs are located south and west of the

Basin Range fault, in the valleys and canyons of the Huachucaa, Here the rocks are relatively impervious, with the exception of water solution crevices through the limestones, and if water is found at all it should be close to the surface. Wells dug in the alluvium at the lower end of the valleys should all reach water at shallow depths (less than 30 feet).

It is much easier to locate a spring than to dig a well.

In general, the springs are formed in the following pattern. Some of the precipitation finds its way into the permeable rooks, usually limestones, which have developed solution channels and caves. There it soon reaches the water table. The impermeable beds check the water and compel it to follow the contact between the permeable and Impermeable beds to the point where it is cut by a canyon. There it issues forth as a spring. Figure 2 shows diagrammatically where these springs are located.

The springs in the northwest corner of the range are related to the Crest Line thrust fault. The Paleozoic limestones and limestone fault breccia lie on Cretaceous red shales, which are relatively im­ permeable. The water follows this thrust down dip to the north and issue forth as springs where this contact has been exposed by erosion#

Pumping operations at the Manila Mine were stopped by court injunction in 1928, when the Pyeatt Ranch spring ran dry. Figure:! shows dia- grammatlcally the relations of these springs to geologic structure. 4" i t - "- 70 - 'H.r-

Figure I

Me Fad in Spring Manila , Mine Pyeett Spring

Crest Line thrust ~ fault

EAST WEST Looking South

# indicates spring

llynestone breccia

__ — ' —~^Z.

Impervious^ Lower ^ Cretaceous

NORTH Looking East SOUTH

DIAGRAMMATIC STRUCTURE SECTIONS SHOWING OCCURRENCE OF SPRINGS IN THE MANILA MINE AREA Figure 2

profile along canyon floor

a \ 1 ^ * —— ^•oPirvlou. * Impervious *, flR granite * '\5.*GiTo‘f6onglomerate WEST EAST Lyle Peak fault Crest Line fault Basin Range fault e indicates spring

DIAGRAMMATIC CROSS-SECTION OF THE HUACHUCA MOUNTAINS, SHOWING RELATION BETWEEN PERMEABILITY OF ROCKS, AND THE OCCURRENCE OF SPRINGS -72-

„ BIBLICKHtAPHY

Alexis, 0.0. The geology of the Lead Mountain area, Pima County, Arizona: Dnir. of Ariz., *. S. thesis, unpublished, 1939.

Billings, M.P. Structural geology* Prentice-Hall Inc., New York, N.Y* 1942.

Bryan, Kirk San Pedro valley, Arizona, and the geographic cycle (abstract): Geol. Soc. Aa. Bull., vol. 37, no. 1, March 1926.

Butler, B. S. Geology and ore deposits of the Tombstone District, Arizona* Ariz* Bur. of Mines, Geol. Series 10, Bull. U3, 1938.

Some Arizona ore deposits: Ariz. Bureau of Mines, Geol. series, no. 12, Bull. no. 145, October, 1938.

Cahalam, V.H. Mammals of the Chiricahua Mountains, Cochise County, Arizona* Jour, of Mammology* vol. 20, November, 1939.

Barrow, R, A. Arizona range resources and their utilization, I, Cochise County* Unix, of Ariz., Coll, of Agri., Tech. Bull. 103, 1944. r

Daugherty, L.H. The Upper Triassic flora of Arizona* Carnegie Institution of Wash., Pub. 526, 1941.

Elsing, M,J# and Heln«mn, R.E.S., Arizona TOtal production: Aria, Bur. of Mines, Dnir. of Aris. Bull. 1*0, 1936.

Path, J. H. Permian stratigraphy and structures. Northern Canelo Hills, Arizona* Am. Assoc. Petroleum Geologists Bull. vol. 32, 1948.

The geology of the Northern Canelo Hills, Semta Cruz County, Arizona* Uhiv. of Ariz., Ph.D. thesis, 1947.

Gidley, J. W. Fossil proboscides and edentate of the San Pedro Valley, Arizona* U.S. Geol. Survey, Prof. Paper 140-B, Jan. 1926. , •73-

GiUully, James Thrust faulting in the Dragoon Mountains, Arizona (abstract): Geol* Soc. Am. Bull., vol. 52, ne. 12, pt. 2, December, 1939#

Emplacement ef the Uncle Sam Porphyry, Tombstone District, Arizona, Am* Jour. Sci. vol. 243, me# 12, December, 1945#

Girty, G* H« Paleontology of the Manzano group of the H e Grande Valley, New Mexico: TJ* S. Geol. Survey, Boll# 389, 1909.

Hill, R. T. The paleontology of the Cretaceous formation of Texas: The invertebrate paleontology of the Trinity division: Proc. Biol* Soc* Wash., 1893.

Islay, R. W. Paleogeographic studies in northeastern Sonorai Geol. Soc. Am. Bull., vol. 50, 1939.

King, R. E, Geological reconnaissance in Sierra Madre Occidental of Mexico: Geol. Soc. Am. Bull, vol. 50, 1939.

Knowlton, F. H. The fossil forests of Arizona: American Forestry, vol. 19, 1913#

Laslty, S, G. Geology and ore deposits of the Little Hatchet Mountains, Hidalgo and Grant Counties, New Mexico: U. S. Geol* Survey, Prof* Paper 208, 1947.

McKee, E. D, Triassic pebbles in northern Arizona containing invertebrate fossils: Am. Jour. Sci., 5th series, vol. 33, 1937.

Ransome, F.L. Geology and ore deposits of the Bisbee quad­ rangle, Arizona: U. S. Geol. Survey, Prof. Paper 21, 1904.

Stoyanow, A. A* Correlation of Arizona Paleozoic formations: Geol* Soc* America Bull*, vol. 47, 1936.

Lower Cretaceous stratigraphy in southeastern Arizona: Geol. Soc. Am., Mem. no, 36, 1949# Swartb, H, S. Birds of the Huachuco. Mountains: Pacific Coast Avefatma No. 4, Cooper Ornithological Club of California*

Taliaferro, N. L* Upper Cretaceous sediments in Mexico: Jour. Geol* vol. 41, 1933*

Wilson, E. D. Geology and ore deposits of the Courtland- Gleeaon region: Univ. of Ariz. Bull. 123, 1927* PLATE 7

A - View of Bobocomari valley taken from northwest corner of the

Huachuca Mountains# The mill site of the Panama Mine appears

in the middle foreground# The Mustang Mountains appear against

the skyline in the middle background# To the right (east) of

the Mustangs, the Whetstone Mountains form the skyline#

B - View of the northern end of the Huachuca Mountains#

(1) Blacktail Canyon

(2) Fault scarp of the Basin Range fault

(3) Sycamore Canyon

(4) Hill of limestone breccia P/a/ e 7 PLATE 8

Thunderstorm forming about noon over the Huachuca Mountain in August, 1947#

Thunder shower over the eastern end of the Mustang Mountains*

Viewed from the northern end of the Huachuca Mountains,

August, 1947# Plaie

A PLATE 9

A - Upper and smaller picture. View of the southwest corner of

Huachuca Peak looking across McClure Canyon# Paleozoic strata

are faulted over Cretaceous strata along the Crest Line thrust

fault* The fault dips about 45 degrees to the northeast, but

since this view is taken nearly normal to the strike of the

fault the angle appears to be much less#

B - Lower and larger picture# View of the northeast side of

Huachuca Canyon and Huachuca Peak, showing Paleozoic strata

faulted over Cretaceous strata along the Crest Line thrust fault* North Sourtk West jE’aLS't 0-

Look Sf’o^f/o>i < HU.O. o/ » K C O u Pco^k A

North e*.st Serstii we j / PLATE 10

A - View taken looking south across Garden Canyon toward Scheelite

Ridge# The Paleozoic beds are dipping southwest 40 degrees#

B - View of Huachuca Peak from the south showing the Paleozoic beds

faulted over the eastward dipping Cretaceous beds#

(1) Devonian Martin limestone

(2) Mississippian Escabrosa limestone

(3) Pennsylvanian Naco limestone

(4) Lookout station on Huachuca Peak R/afc /O

£nst West PLATE 11

A - Bedding Cambrian laminae in Bolsa quartzite® Picture taken

near road in Huachuca Canyon.

B - Cross-bedding in Cambrian Bolsa quartzite® Notice coarser gravels

in this formation® Picture taken near road in Huachuca Canyon® // Plate

0 PLATE 12

A - Mlsslsslpplan Esoabrosa limestone lying in fault contact

on the Abrigo formation north side of Garden Canyon*

B - Abrigo formation exposed in road cut in Garden Canyon Plate IS PLATE 13

A - View of Lyle Peak from the southeast, showing steeply southwest

dipping Permian limestone beds*

B - Gently southwest dipping Permian limestones in the upper part of

Garden Canyon west of the Garden Canyon fault* P t a + e 13

B PLATE 14

A - View of Lower Cretaceous limestone conglomerate from the south

at a point near the Sylvania Ranch• The ridge is a southwest

spur off Peterson Peak. The vertical dip of the beds is shown

on the small peak in the right hand side of the picture»

B - Transverse section of Araucarioxylon sp. This specimen was

collected from a sandstone bed east of and near the Eureka Mine

tunnel.

Description of section.

Annual rings not distinct; no resin ducts; uniseriate rays.

Magnification xlOO A PLATE 15

A - Radial section from same specimen of Arajicarloxvlon sp.

shown in Plate 14*

Description of sections

Uniseriate and sometimes biseriate bordered pits (typical

Araucarian pitting) on the radial walls of tracheids*

Magnification x 100•

B - Tangential section of above •

Description of sections

No pits ontangential rails of tracheids• rays uniseriate

from one to 18 or 20 cells high; no branch traces, thus

ruling out genus Woodworthia.

Magnification x 100. Plats ]5 PLATE 16

A - Oyster bank in the Lower Cretaceous limestone formation. The

exposure is about two miles up Parker Canyon from the Montezuma

Pass Road. The Lower Cretaceous beds in Parker Canyon are near

vertical. In this picture the hammer head is horizontal, while

the handle roughly approximates the dip of the beds. The yellow

shale beds to the right (east) of the oyster reef contain many

remains of Glauconia branneri.

B - A closer view of the oyster bank described above. Plate 16 PLATE 17

A - Specimens of Ostrea ragsdolei found in the oyster reef

illustrated on Plate 16• About 1/6 natural size.

B - Specimens of Glauconla branneri found near the oyster reef

illustrated on Plate 16. About natural size. P/ate 17 PLATE 18

A - Looking north across the head of Rough Canyon on the west

slopes of the Huachuca Mountains* All the beds shown are

of Lower Cretaceous age* The northward dipping ridge shown

in the middle foreground is the nose of the Rough Canyon anti­

cline, which plunges to the northwest*

B - Same as A above. P/afe f 8

West S O L j t

A

V West SosT

B PLATE 19

A - Lower Cretaceous strata seen looking north from up the south

fork of Huachuca Canyon• The axis of the Rough Canyon syncline

passes through the low point on the skyline in the extreme left

(west) of the picture*

B - Vertical Lower Cretaceous strata of the upper clastic formation

about one mile up Parker Canyon from the Montezuma Pass road*

The prominent beds are conglomerate containing some pieces of

volcanic origin* The weak beds shown are red and yellow shales* Plate 1

A T j 'O s . j PLATE 20

A - Cretaceous beds on the west side of the Huachuca Mountains

up Algerita Canyon and about 3/<4 miles east of the Foster

Ranch buildings# The strata appear to dip east (right) but

actually dip west (left) 65 degrees# The limestone formation

is exposed in the saddle shown in the lower middle foreground

of the picture*

B - Cretaceous strata seen looking eastward into the head of

Algerita Canyon* These beds appear to dip east but actually

dip steeply to the west* P la te 2 0

iVesV'

A

)VesY ^ a -sT PLATE 21

A - Sandstone, siltstone and tuff beds found in the Tertiary

volcanics» This exposure is one mile up Collins Canyon, which

is located in the southwest corner of the area mapped (Plate !)•

Collins Canyon runs into Parker Canyon about one hundred yards

west of the Hathaway Ranch buildings.

B - Closer view of A above. These beds are sandstones probably

derived in part from earlier volcanic flows. The material

shown breaks out as flag stones one to two inches thick and

from six to eighteen inches in length and breadth. Plate 21 PLATE 22

A - Flat lying sandstones, tuffs and conglomerates# These beds are

found interbedded with the Tertiary volcanic flow. The exposure

is in the stream bed of Parker Canyon downstream (west) of the

Montezuma Pass Road and upstream (east) from the Hathaway Ranch

buildings# These beds are believed to lie stratigraphically

in the same position as the beds illustrated on Plate 21#

B - Tertiary rhyolite porphyry flow exposed in Parker Canyon down­

stream from the Hathaway Ranch buildings# The angular inclusions

are of volcanic origin and are found throughout the flow# T o p PLATE 23

Pliocene Gila conglomerate exposed north and within 200 yards of the Basin Range fault in the drainage of Sycamore

Canyon* These beds are semi-consolidated* The boulders are primarily from earlier Tertiary volcanic flows, but boulders derived from the Paleozoic limestones are also found*

Same as above

PLATE 24

A -

B - Pliocene Gila conglomerate exposed near Basin Range fault in

Sycamore Canyon. The boulder upon which the hammer rests is

derived from post Tertiary volcanic conglomerate made up of

Tertiary volcanic rocks and Paleozoic limestones. Plate 2 f

r

B PLATE 25

A - Exposure of semi-consolidate silt stones, clays and sandstones

in the creek down stream and within two hundred yards of the Elgin

railroad station. These beds contain completely weathered vol­

canic fragments from one to five inches in their longest dimension.

They are believed to be equivalent to the Gila conglomerate shown

in Plates 23 and 2A but are finer because they were deposited

farther away from the source.

B - Same as above. The faulting and tilting of beds since their

deposition are shown in this view. Plate 25 PLATE 26

A - View seen looking southeast down Garden Canyon from on top

Permian limestone ridge. Mississippian Escabrosa limestone

is faulted over east dipping Lower Cretaceous beds along the

Crest Line thrust fault#

B - Closer view of Crest Line thrust fault# This is the same area

shown in the left side of A above# P/af e 2 6 A A v> Z5 PLATE 27

Huachuca Peak as seen from the southwest* The Paleozoic beds

are faulted over the Cretaceous along the Crest Line thrust

fault* The eastward dip of the Cretaceous can be discerned

just above the point marked x on the photograph* Note the

drag folding in the Pennsylvanian strata*

View of the southeast spur of Huachuca Peak, taken from the

south across McClure Canyon* Plate 27

ft/eirth VV G'S'f' S o i m TH © cu^T*

6 PLATE 28

A - Looking west along the scarp of the Basin Range fault on the

northern edge of the Huachuca Mountains in the drainage of

Sycamore Canyon. On the left (south) is the upthrown pre-

Cambrian granite forming the foot wall of the fault. To the

right is Pliocene Gila conglomerate which forms the hanging

wall of the fault.

B - Same area as in A above but looking south toward the Huachuca

Mountains. Notice the gorge cut in the pre-Cambrian near the

fault. Further south the stream is not so deeply entrenched

nor is its gradient as steep as that near the fault. Plaie 2 8

9

A PLATE 29

A - Closer view of gorge described on Plate 28. The abrupt change

in gradient is seen near point x. The Basin Ranch fault is

less than 100 yards north of this point*

B - Another view of A above except at a greater distance* In the

background and forming the skyline is the northern end of the

Huachuca Range* The grass covered slope in the foreground is

underlain by Pliocene Gila conglomerate* Notice the fault

surface in right (west) side of the picture* This surface

is nearly a smooth plane* P/afe 29 West CD EXPLANATION

SEDIMENTARY ROCKS IGNEOUS ROCKS

Quaternary and Tertiary volcanic k*ock C e n o z o i d

upper clastic -fot-mcdion Pf-e-'C | /4R^r| g ra n ite

limestone formation SYMBOLS

\owe / #ted ^^<30 Strike and dip of overturned beds tormaTro/TS /to Strike of vertical beds

So/s a quart2.1 fe 6* Horizontal beds

P L A T E 2

\ > A/c /

/___ wsw

j 7500 -- 7000

/ Kuc W

7500 -■ 750Q 7000 ■■ 7000 •" Co50C

-- 4000 - - 3500

\

^500 y fOOO -- #000 7500 -- 7000 " 650O -- (oDGO ~ ■

\ ' \ -■ 4500 *-4ooo -- 3 5 0 0

700 0 t 70(00 " 6 5 0 0 Z < / -- 6000 "55(^0

/ C n / i

3 5 0 0

GEOLOGIC STRUCTURE SECTIONS OF THE NORTHERN PART OF THE HUACHUCA MOUNTAINS ALONG LINES SHOWN ON PLATE |

Sc die 3/ 6 y c

0 yi 1 I?* 2 mi /qs

1 1 1 ■— Le— ■e—*- - ^

/949

£ 0 L O ^ A 0 Q phoehix o A S A C GRANDE N E MAP INDEX /VOCAI/.E5 MAGDALENA O O HERNIOSlLLO S anta f A V i„/V)AAV / z W

. ° 0CLf£-SO/V ° 7.™ cruz " r o / w M r r - p v ^ ro MONTEZUMA O O c o u f f r i - A N D R f H C E V ARi CA3(ytL0^VA O i r a z o c a h O f PA R A U H A S ESQUEDA O O LORDSBuBG -; £ O HACKt ira D Ls Ajos Los De Sierra. ira D Sn Jo^e San De Sierra. ite at.A Me.\u*nia.!vs Ha.tc.hAtLittle P a ta g o n ia . M ount ount M . ia n o g ta a P PLATE3

a / es

TJOTTED STATES DEPARTMENT OF THE INTERIOR THE TOPOGRAPHIC MAPS OF THE UNITED STATES

The United States P? ey is making a series of A survey of Puerto Rico is now in progress. The scale of ing spurs separated by ravines. The spurs are truncated at standard topographic e United States. This the published maps is *^5. their lower ends by a sea cliff. The hill at the left terminates work has been in progr and the published maps The features shown on topographic maps may be arranged in abruptly at the valley in a steep scarp, from which it slopes cover more than 47 percent country, exclusive of outlying three groups— (1) water, including seas, lakes, rivers, canals, gradually away and forms an inclined tableland that is trav­ possessions. swamps, and other bodies of water; (2) relief, including ersed by a few shallow gullies. On the map each of these The maps are published on sheets that measure about 16£ by mountains, hills, valleys, and other features of the land surface; features is represented, directly beneath its position in the 20 inches. Under the general plan adopted the country is (3) culture (works of man), such as towns, cities, roads, rail­ sketch, by contour lines. divided into quadrangles bounded by parallels of latitude and roads, and boundaries. The symbols used to represent these The contour interval, or the vertical distance in feet between meridians of longitude. These quadrangles are mapped on features are shown and explained below. Variations appear on one contour and the next, is stated at the bottom of each map. different scales, the scale selected for each map being that which some earlier maps, and additional features are represented on This interval differs according to the topography of the area is best adapted to general use in the development of the country, some special maps. mapped: in a flat country it may be as small as 1 foot; in a and consequently, though the standard maps are of nearly uni­ All the water features are represented in blue, the smaller mountainous region it may be as great as 250 feet. In order form size, the areas that they represent are of different sizes. streams and canals by single blu^ lines and the larger streams that the contours may be read more easily certain contour lines, On the lower margin of each map are printed graphic scales by double lines. The larger st:'earns, lakes, and the sea are every fourth or fifth, are made heavier than the others and are showing distances in feet, meters, miles, and kilometers. In accentuated by blue water lining or blue tint. Intermittent accompanied by figures showing altitude. The heights of many addition, the scale of the map is shown by a fraction expressing streams—those whose beds are dry for a large part of the year— points—such as road intersections, summits, surfaces of lakes, a fixed ratio between linear measurements on the map and cor­ are shown by lines of blue dots ai d dashes. and benchmarks—are also given on the map in figures, which responding distances on the ground. For example, the scale Relief is shown by contour lii es in brown, which on a few show altitudes to the nearest foot only. More precise figures 5^55 means that 1 unit on the map (such as 1 inch, 1 foot, or 1 maps are supplemented by shading showing the effect of light for the altitudes of benchmarks are given in the Geological Sur­ meter) represents 62,500 of the same units on the earth’s surface. thrown from the northwest across the area represented, for the vey’s bulletins on spirit leveling. The geodetic coordinates of Although some areas are surveyed and some maps are com­ purpose of giving the appearance of relief and thus aiding in triangulation and transit-traverse stations are also published in piled and published on special scales for special purposes, the the interpretation of the contour lines. A contour line repre­ bulletins. standard topographic surveys and the resulting maps have for sents an imaginary line on the ground (a contour) every part Lettering and the works of man are shown in black. Bound­ many years been of three types, differentiated as follows: of which is at the same altitude (ibove sea level. Such a line aries, such as those of a State, county, city, land grant, town­ 1. Surveys of areas in which there are problems of great could be drawn at any altitude, but in practice only the con­ ship, or reservation, are shown by continuous or broken lines of public importance—relating, for example, to mineral develop­ tours at certain regular intervals of altitude are shown. The different kinds and weights. Public roads suitable for motor ment, irrigation, or reclamation of swamp areas—are made with datum or zero of altitude of the Gd logical Survey maps is mean travel the greater part of the year are shown by solid double sufficient detail to be used In the publication of maps on a sea level. The 20-foot contour w arid be the shore line if the lines; poor public roads and private roads by dashed double scale of 5-555 (1 inch = one-half mile) or -555 (1 inch = 2,000 feet), sea should rise 20 feet above nwau sea level. Contour lines lines; trails by dashed single lines. Additional public road with a contour interval of 1 to 100 feet, according to the relief show the shape of the hills, mountains, and valleys, as well as classification if available is shown by red overprint. of the particular area mapped. their altitude. Successive contour lines that are far apart on Each quadrangle is designated by the name of a city, town, 2. Surveys of areas in which there are problems of average the map indicate a gentle slope, lines that are close together or prominent natural feature within it, and on the margins of public importance, such as most of the basin of the Mississippi indicate a steep slope, and lines that run together indicate a the map are printed the names of adjoining quadrangles of and its tributaries, are made with sufficient detail to be used in cliff. which maps have been published. More than 4,100 quad­ the publication of maps on a scale of 5— (1 inch = nearly 1 The manner in which contour lines express altitude, form, rangles in the United States have been surveyed, and maps of mile), with a contour interval of 10 to 100 feet. and grade is shown in the figure jtelow. them similar to the one on the other side of this sheet have 3. Surveys of areas in which the problems are of minor been published. public importance, such as much of the mountain or desert region of Arizona or New Mexico, and the high mountain area maps have been published in the form of folios. Each folio of the northwest, are made with sufficient detail to be used in includes maps showing the topography, geology, underground the publication of maps on a scale of (1 inch = nearly 2 structure, and mineral deposits of the area mapped, and several miles) or 55^55 (1 inch = nearly 4 miles), with a contour interval pages of descriptive text. The text explains the maps and of 20 to 250 feet. describes the topographic and geologic features of the country The aerial camera is now being used in mapping. From the and its mineral products. Two hundred twenty-five folios have information recorded on the photographs, planimetric maps, been published. which show only drainage and culture, have been made for some Index maps of each State and of Alaska and Hawaii showing areas in the United States. By the use of stereoscopic plotting the areas covered by topographic maps and geologic folios pub­ apparatus, aerial photographs are utilized also in the making of lished by the United States Geological Survey may be obtained the regular topographic maps, which show relief as well as free. Copies of the standard topographic maps may be obtained drainage and culture. for 10 cents each; some special maps are sold at different prices. A topographic survey of Alaska has been in progress since A discount of 40 percent is allowed on an order amounting to 1898, and nearly 44 percent of its area has now been mapped. $5 or more at the retail price. The discount is allowed on an About 15 percent of the Territory has been covered by maps order for maps alone, either of one kind or in any assortment, On a scale of —555 (1 inch = nearly 8 miles). For most of the or for maps together with geologic folios. The geologic folios remainder of the area surveyed the maps published are on a are sold for 25 cents or more each, the price depending on the scale of ^55 (1 inch = nearly 4 miles). For some areas of par­ size of the folio. A circular describing the folios will be sent ticular economic importance, covering about 4,300 square miles, on request. the maps published are on axscale of 5^55 (1 inch —nearly 1 mile) Applications for maps or folios should be accompanied by or larger. In addition to the area covered by topographic maps, The sketch represents a river valley that lies between two cash, draft, or money order (not postage stamps) and should be about 11,300 square miles of southeastern Alaska has been hills. In the foreground is the sea, with a bay that is partly addressed to covered by planimetric maps on scales of and 5 ^ . enclosed by a hooked sand bar. On each side of the valley is THE DIRECTOR, The Hawaiian Islands have been surveyed, and the resulting a terrace into which small streams have cut narrow gullies. United States Geological Survey, maps are published on a scale of 5^55. The hill on the right has a rounded summit and gently slop- November 1937. Washington, l). C.

STANDARD SYMBOLS NOTE:—Effective on ami after October 1, 194H, the price of standard topographic quadrangle maps will be 20 cents each, with a discount of 20 percent on orders amounting to $10 or more at the retail rate. CLiTURE (printed #j black)

.m a .j nfr------y B r e a k w a t e r H E * MB Brans Cliff .Trail Eleetfic Tunnel P o w e r W h a r v e s Bridge Drawbridges Ferry d w e l l i n g Toeud private road r«i Ire < < I transmission a n d j e t d e s (•point upstr'aam ) line

P a m with lock Canal lock US.township and State line County" line > T o w n s h i p Iteservatimi L a n d g r a n t o r Small park or h-rangedalion (J. S.mineral !point vpotnoam Section lillCS ■ >1 li strict line h n e n e cemetery line point or transit- m o n u m e n t and recovered comers traverse station

. L.S S. Le"’] ffl j n . c as Boundary Bench mark Cemereries ^ Church, School Coke ovens T a n k s a n d Oil a n d M i n e o r P r o s p e c t Shaft. Mine tunnel Mine tunnel L i g h t h o u s e Coast Guard m o n u m e n t (auj-plementcay benofi (ebiatuu/taxhod on oil reservoir-h g a s wells quarry (showing direction) o r be a c o n station rruirto shown. Ijy oroma and rmoont rruxps) blat'ht dffuros without I+ tta rin g j RELIEF WATER 1 printed in brown) (printed in blue)

% Elevation above | Co n t o u r s D e p r e s s i o n L ev ee Streams .ills a n d Intermittent C a n a l s o r Aqueducts or Aqueduct L a k e o r TIri su r v e y e d m e a n sea level WConi. ’/rm \\owing contoxmef tpids s t r e a m s a n d . d i t e h e s water-pipes tunnels p o n d . s t r e a m a n d (in biaok >n rv

, ^ U! m n .

W a s h M i n e d u m p s Intermittent Glariet ripring Well M a r s h S u b m e a • g'ecl fof' sTionyx if) mitring dfjfcd-is lake

WOODS .* (w‘U» ehown, printed in green) > a A s; u

p tha I i 111 a ti *>y p _Aroians 01 longitux. juadn i.... different scales, the scale selected for each map being that which some earlier maps, and additional features are represented on This interval differs according to the topography of the area is best adapted to general use in the development of the country, some special maps. mapped: in a flat country it may be as small as 1 foot; in a and consequently, though standard maps are of nearly uni­ All the water features are re .-resented in Blue, the smaller monnbtiimm region it may be as gm il as 250 feet. In order form size, the areas that they represent are of different sizes. streams and canals by single blue lines and the larger streams that the contours may be read more easily certain contour lines, On the lower margin of each map are printed graphic scales by double lines. The larger streams, lakes, and the sea are every fourth or fifth, are made heavier than the others and are showing distances in feet, meters, miles, and kilometers. In accentuated by blue water lining or blue tint. Intermittent accompanied by figures showing altitude. The heights of many addition, the scale of the map is shown by a fraction expressing streams—those whose beds are dry for a large part of the year— points—such as road intersections, summits, surfaces of lakes, a fixed ratio between linear measurements on the map and cor­ are shown by lines of blue dots and dashes. and benchmarks—are also given on the map in figures, which responding distances on the ground. For example, the scale Relief is shown by contour flues in brown, which on a few show altitudes to the nearest foot only. More precise figures 5^55 means that 1 unit on the map (such as 1 inch, 1 foot, or 1 maps are supplemented by shading showing the effect of light for the altitudes of benchmarks are given in the Geological Sur­ meter) represents 62,500 of the same units on the earth’s surface. thrown from the northwest acroLs the area represented, for the vey’s bulletins on spirit leveling. The geodetic coordinates of Although some areas are surveyed and some maps are com­ purpose of giving the appearance of relief and thus aiding in triangulation and transit-traverse stations are also published in piled and published on special scales for special purposes, the the interpretation of the contour lines. A contour line repre­ bulletins. standard topographic surveys and the resulting maps have for scuts an imaginary line on the ground (a contour) every part Lettering and the works of man are shown in black. Bound­ many years been of three types, differentiated as follows: of which is at the same altitude above sea level. Such a line aries, such as those of a State, county, city, land grant, town­ 1. Surveys of areas in which there are problems of great could be drawn at any altitude, but in practice only the con­ ship, or reservation, are shown by ■continuous or broken lines of public importance—relating, for example, to mineral develop­ tours at certain regular intervals of altitude are shown. The different kinds and weights. Public roads suitable for motor ment, irrigation, or reclamation of swamp areas—are made with datum or zero of altitude of the Geological Survey maps is mean travel the greater part of the year are shown by solid double sufficient detail to be used in the publication of maps on a sea level. The 20-foot contour would he the shore line if the lines; poor public roads and private roads by dashed double scale of — (1 inch = one-half mile) or — (1 inch = 2,000 feet), sea should rise 20 feet above mean sea level. Contour lines lines; trails by dashed single lines. Additional public road with a contour interval of 1 to 100 feet, according to the relief show the shape of the hills, mountains, and valleys, as well as classification if available is shown by red overprint. of the particular area mapped. their altitude. Successive contour lines that are far apart on Each quadrangle is designated by the name of a city, town, 2. Surveys of areas in which there are problems of average the map indicate a gentle slope, lines that are close together or prominent natural feature within it, and on the margins of public importance, such as most of the basin of the Mississippi indicate a steep slope, and lines that run together indicate a the map are printed the names of adjoining quadrangles of and its tributaries, are made with sufficient detail to he used in cliff. which maps have been published. More than 4,1(X) quad­ the publication of maps on a scale of ^ (1 inch = nearly 1 The manner in which contour lines express altitude, form, rangles in the United States have been surveyed, and maps of mile), with a contour interval of 10 to 100 feet. and grade is shown in the figure below. them similar to the one on the other side of this sheet have 3. Surveys of areas in which the problems are of minor been published. public importance, such as much of the mountain or desert Geologic maps of some of the areas shown on the topographic region of Arizona or New Mexico, and the high mountain area maps have been published in the form of folios.. Each folio of the northwest, are made with sufficient detail to he used in includes maps showing the topography, geology, underground the publication of maps on a scale of —55 (1 inch = nearly 2 structure, and mineral deposits of the area mapped, and several miles) or — 5 (1 inch = nearly 4 miles), with a contour interval pages of descriptive text. The text explains the maps and of 20 to 250 feet. describes the topographic and geologic features of the country The aerial camera is now being used in mapping. From the and its mineral products. Two hundred twenty-five folios have information n v oiritri on the nhotoirranhs. nlanimetrin mans. 1 • 1 V 1 1 . ■ 1 » >-x - 1 PLATE 5

terrace gravels ------unvonfo t-rrtiiy------G//a Conglomerate. ,'Q 9 A ^ P.V C.ont

rhyolite porphyry t/ows +UffS, CLnd agg/omerat

contact not seen unconformity (?)

upper elastic f o r m a t to n (sandstones, shales,

/ o w e r c /a s / / c. to r iv at 'on (sandstones , sho-les, xnd. vole an I c, tio )

/ 1 m rsto/y e c o/ig/e m e r-o J e

r . . i mostly dio.*-K limestones some rea c/a-sf/v heUs

-i 2 u Li Pern s y a.ni

Naco l i m e s t o n e

E s cabr o s C o c>i / S g. _t_m. B o lS a cfvart z. ite u n c o n f or /r

Rre - Cambr.ar coarse granite

G E N E R A L I Z E D C O L U M N A R SECTION HUACHUCA MOUNTAINS, ARIZONA

o to oo u.ooo 3 co o 4 cc o ffooo 6000 f eet I r— 1 , ' , 1 . ' , 1 v— 1 _ . S O 0 ISOO ZSOO 3SOO 4 BO O SSOO -Tc CT

c o m a r/ ft/%

/ Syc xmorc Can vo/7 • /k Ccipturinq 1 n

U \ ,/ J iaij r S c a le : one inch =r one m iie

> o o I n c h 'c a t es ///nits of jb as/ns

PLATE 6 - S T R E A M PIRACY NORTHERN END OF THE HUAChUC A MOUNTAINS

70

Ft^ur-Q. 1

I limestone P.k I^ox. i . c. hrneslone b r e e d a /v'arJa Mine Af c F'cl a < ri ^>pr i r> j

L.ov^'ir Cretaceous

W e sT

• l/7j/cat e1* t.prnij

\ T / / / ' /. ' . C r e 5"^ Line thr-vsl z

J m fj C r v I u U 5 zv c. r C retexe e ni'

Norih\ Soufh

Diagram meet ic. 'Structure •Sections Showing O c c u r r e n c e o/" S p r in q s in 1 nc. /Vlanii*, Mine A r e a v s floor fa u lt canyon o*f Basin Range profile along profile ,3 o huoa Mountains j ZVuac Figure 2. Crest Paott Line of Springs - Sec.fi on - Sec.fi o f t h e V' 5 ^ r o s e astonc A mA the Occurrence and } } s p e rvi o ur ^ rvio / P e p e j r K Indlcectes Indlcectes spring o z • Pi a^ratn mat ic ic mata^ratn Pi C R Show/hg th e Relation b e tw e e n S t r u c t u r e } P erm(xbihty e

"d jr* SI Sf VNO

r !