Arizona Geological Survey DGM-48 ( ), v. 2.0

110°15' 110°12'30" 110°10' 110°7'30" 571000 572000 573000 574000 575000 576000 577000 578000 579000 580000 581000 582000 ' 0 °

Qy1 2 '

Qy1 Qy2 Qi2 3

0 QTsd ° Qy1 GEOLOGIC MAP OF THE SAINT DAVID 2

3 Qy1 Qsf Qi3 Qi1 Qys QTsd Qy1 Qsf Qi2 Qi1 Qi2 Qi1 Qi3 Qsf Qi2 Qi2 Qi2 Qi3 Qy1 Qy1 Qi3 Qo Qi3 Qi2 d Qi3 7½' QUADRANGLE, COCHISE COUNTY, Qi2 Qi3 Qi1 QTsd QTsp Qi1 Qi1 Qsf Qi2 Qi2 Qi2 Qi2 Qy1 Qy1 Qo 0 Qsf Qy1 Qy1 Qy1 0 0 Qsf 0 0 Qys Qy2 0 0 Qys 0

4 4 ARIZONA Qy1 5 5

3 Qi2 Qy1 3 Qy2 Qi1 QTsd

Qy1 Ann Youberg and P. Cook QTsd Qi1 Qyaf Qi1 QTsd Qy2 Qy2 Qi2 Arizona Geological Survey Digital Qy1 Qys Qy2 Qi2 QTsd Geologic Map 48 (DGM-48), version 2.0

Qy2 Qy2 0 0

0 QTa 0 0 Qy1 QTa 0 9 9

3 3 April 2009 5 5 3 QTsd 3 Qy1 Qy2 Qy2 Qi2 Qi2 QTa Qi2 Qy2 Qy1 Qi2 Qys 1:24,000 scale Qi2 Qi2 Qy1 Qy1 Qy2 Qys Qi3 Citation for this map: QTa Qys Youberg, A., and Cook, J.P., 2009, Geologic Map of the Saint David

Qy1 Qy2 Qy1 7½' Quadrangle, Cochise County, Arizona: Arizona Geological Survey Qi2

0 0 Digital Geologic Map 48 (DGM-48), version 2.0, 1 sheet, layout scale 1:24,000. 0 0 0 0

8 Qi2 8 3 Qy1 3 5 5 3 Qi3 3 (also available in Adobe pdf format on CD-ROM) Qy2 Qi1 Tsp Qi3

QTsd Qy1 Qi1 Not to be reproduced for commercial purposes Qi2 Qi2 Qy2 Qyaf Qi1 Qyc Research supported by the U.S. Geological Survey, National Cooperative Geologic Mapping Program, Qi2 under USGS award #04HQAG0072. The views and conclusions contained in this document are those Qy2 Qi1 Qi2 of the authors and should not be interpreted as necessarily representing the official policies, either Qi2 Qys Qyc Qy1 expressed or implied, of the U.S. government. The Arizona Department of Water Resources Qi3 Qi1 provided funding for map revisions depicted in DGM-48, version 2.0. Qy1 Qi2 Qy2 Qy2 Qi2 Qy1 Qi3

0 Qy3 0 0 Qi2 0 0 Qys 0 Acknowledgements:

7 Qy2 7

3 Qy2 Qy1 3 5 5

3 Qy2 3 Qy1 Thank you to Dr. Max Kartchner for providing access to the lower piedmont east of the town Qy3 Qy1 of Saint David, and to Dragoon Mountain Ranch for gate access. Qy2 QTsd QTa Qy1 Qi2 Qy1 Qi3 Qy1 Pearthree was the cartographer for DGM-48, version 2.0. Qy3 Qys Qy2 Qy1 Qi3 Qys Qy2 Qys Qyaf Qy2 Qyaf QTsd Qy1 Qy2 QTsd Qy2 QTsd Qy2 Qy1 Qi1 QTsd Qi1 QTa Qy1 " Qy1 0 3

Qys ' Tsp Qys Qy1 " QTsd 7 Map Unit Descriptions

0 Tsp 5

Qyc ° 3 ' Qy2 1 7

0 Qi3 0

Qsf 3 0 0 5 Tsp Qi2 ° 0 0 6 6 1 Qy2 Qi3 3 3

3 Qy2

5 5 Other units 3 3 QTa Qi1 Qy1 Qy1 Qi3 Qi3 QTa Qi2 QTsd Plowed areas - historically or actively plowed fields, irrigated pastures, and other lightly Older Holocene alluvium - Older Holocene terraces found at scattered locations along incised QTsd Qi1 Qy1 Tsp Qsf disturbed ground. drainages throughout the study area, and isolated alluvial fans at the base of the piedmont. Qy2 Qi1 Qy1 Qy1 Qy2 Qy1 surfaces are higher and less subject to inundation than adjacent Qy2 surfaces. In areas QTsd Qy1 of deep incision these surfaces are now isolated from flooding. Qy1 terraces are generally Qi3 Tsp Qsf Disturbed ground - stock tanks and ditches. Qi2 Qi1 d planar but local surface relief may be up to 1 m where gravel bars are present. Qy1 surfaces Qys Qsf Qi1 Qi3 are 2 to 6 m above adjacent active channels. Surfaces typically are sandy but locally have unvarnished open fine gravel lags or pebble and cobble deposits. Terraces along major Tsp QTa Qy1 drainages vary from 2 to 4 m thick Qy1 deposits over basin fill deposits to basin fill strath Qi2 San Pedro River alluvium terraces with less than 1m of Qy1 deposits. Qy1 soils typically are weakly developed, with Qi1 Qi1 Tsp Qy1 0 Qsf 0 some soil structure but little clay and no to stage I calcium carbonate accumulation (see 0 0 0 0

5 Qy2 5 Active river channel deposits - Deposits are dominantly unconsolidated, very poorly sorted Machette, 1985, for description of stages of calcium carbonate accumulation in soils). Yellow 3 QTsd 3

5 QTa 5 3 3 Qycr Qi3 sandy to cobbly beds exhibiting bar and swale microtopography but can range from fine silty brown (10YR Munsell soil color chart) soil color is similar to original fluvial deposits. Tsp QTsp beds to coarse gravelly bars in meandering reaches based on position within the channel. Clasts are typically well-rounded but may be angular to sub-angular. Qycr deposits are Qys Fine-grained Holocene alluvium derived from the St. David Formation - Thin to moderate (< Tsp Qi1 typically unvegetated to lightly vegetated and exhibit no soil development. Qycr deposits are Qys 3m), fine-grained Holocene alluvium derived from, and overlying, basin fill deposits (units Qsf, entrenched from 30 cm to 5 meters or more below adjacent early historical floodplain deposits QTsp, QTsd). It is composed mostly of silts and clays with color reflecting that of the parent QTsd QTa depending on location, geomorphic relationship, and local channel conditions. Although much Qy1 material. Qys is typically found in fans at the base of basin fill outcrops along the edges of the of the San Pedro River was a perennial stream historically, some modern sections are dry or peidmont. Qi1 Qi3 marshy at the surface throughout much of the year. These deposits are the first to become Qi3 Qy2 Tsp submerged during flow events and can be subject to deep, high velocity flow and lateral bank Qy1 Qi1 QTsd QTsd erosion. Late Pleistocene alluvial fan and terrace deposits - Slightly to moderately dissected relict Qy1 Qi3 alluvial fans and terraces. Active channels are incised up to about 2 m below Qi3 alluvial fan Qi1

0 Qi1 Qi3 0

0 0 surfaces on upper and middle piedmont areas; and up to about 8 m below Qi3 terraces along 0 0 Historical river terrace deposits - Terrace deposits that occupy elevations from 1 to 2 meters 4 4

3 3 drainages on the lower piedmont. Qi3 fans and terraces are lower in elevation than adjacent 5 5 Qy3r 3 3 above Qycr deposits and are inset below the pre-incision historical floodplain. These surfaces Qi1 Qi3 older surfaces. Qi3 relict alluvial fans within the Saint David quadrangle are derived mainly Qy1 Qi1 are generally planar but exhibit bar and swale microtopography. Although no soil development from granite and are fairly fine-grained. These Qi3 surfaces are dark brown and smooth with is present, dense grasses and small mesquite trees abound. Sediments composing these grussy gravel lag. Qi3 terraces consist of pebbles, cobbles, and finer-grained sediment, and Qi2 deposits are poorly sorted silt, sand, pebbles and cobbles. Pebbles and cobbles are Qi3 are moderately reddened. Qi3 terraces commonly have bar and swale topography, and have Qi1 well-rounded to sub-angular. Trough crossbedding, ripple marks, and stacked channel Qy1 moderately preserved, loose to moderately packed pebble and cobble lags. Surface clasts Qy2 Qi1 deposits viewable in cross-section indicate deposition in a low to moderate energy braided Qi1 typically exhibit weak to moderate rock varnish. Qi3 terraces along major washes tend to be QTsd stream environment. These deposits are prone to flooding during extreme flow events, and strath terraces in basin fill deposits with thin (<2 m) Qi3 deposits on top. Qi3 soils are Qys Qi3 undercutting and rapid erosion of Qy3r surfaces is possible during lower flow events. Tsp moderately developed, with yellow brown to brown (10 YR to 7.5 YR) clay loam to light clay QTsd argillic horizons and stage I to stage II calcium carbonate accumulation. Qi3 Qy1 Latest Holocene to historical river terrace deposits - Deposits associated with the floodplain 2 Tsp Qi3 Qy1 Qy r that existed prior to the early historical entrenchment of the San Pedro River (Hereford, 1993; Tsp Qyc QTsd Qy1

0 0 Middle to late Pleistocene alluvial fan and terrace deposits - Moderately to highly dissected

0 Qy2 0 Huckleberry, 1996; Wood, 1997). Qy2r deposits are associated with broadly planar surfaces 0 Qy2 QTsd 0 Qi2

3 QTsd 3 relict alluvial fans with strong soil development found throughout the map area. Qi2 surfaces 3 3

5 QTsd Qi3 Qy2 5 that locally retain the shape of historical river meanders. Qy2r surfaces are up to 7 meters 3 Qy1 3 are drained by well-developed, moderately to deeply incised tributary channel networks; Qy2 Qi1 above modern Qycr deposits and are the most extensive river terraces in the valley. Qy2r channels are typically several meters below adjacent Qi2 surfaces. Well-preserved, planar Qi2 Qy1 sediments were deposited when the San Pedro River was a widespread, shallowly-flowing QTsp Qy2 surfaces are smooth with scattered pebble and cobble lags; surface color is reddish brown; river system and are dominated by fine grained floodplain deposits. Dense mesquite bosque surface clasts are moderately to strongly varnished. More eroded, rounded Qi2 surfaces are and tall grass is typically present on these surfaces except where historic plowing or grazing Tsp QTa Qi1 characterized by strongly varnished, scattered, cobble to cobble and pebble lags with broad QTsd QTsp has taken place. These surfaces appear predominantly fine grained at the surface due in part Qi2 Qy1 ridge-like topography. Soils typically contain reddened (5 to 7.5 YR), modestly clay-rich Qi2 to the input of organic matter and windblown dust deposition but are composed of Qi1 argillic horizons, with clay skins and subangular blocky structure. Underlying soil carbonate Qsf interfingering coarse sandy to pebbly braided channel and fine sand to silty river floodplain Tsp Qy2 Qi1 development is typically stage III with abundant carbonate through at least 1 m of the soil QTsd Qy1 deposits. Where Qy2r deposits are moderately to deeply incised they are not subject to Qyc profile. This unit loosely correlates to Gray’s (1965) granite wash unit. Qy2 QTsc inundation by river floods, but they may be flood-prone in areas with less channel incision. QTsl Qy2 Qi1 Qy2r deposits are subject to catastrophic bank failure due to undercutting and lateral erosion Qy2r Qy2 Qy2 QTsl QTsl QTsp during flow events. Distal piedmont fan deposits (Qy2 ,Qyaf, and Qys) onlap onto Qy2r Early to middle Pleistocene alluvial fan and terrace deposits - Deeply dissected relict alluvial

0 Qi2 0

0 Qy3r QTa 0 Qi1 0 QTsd 0 deposits although an interfingering relationship likely exits in the subsurface. fans found on upper piedmonts. Qi1 surfaces form rounded ridges that are higher than 2 2 3 3

5 Qy2 Qy1 5

3 Qi3r 3 adjacent Qi2 surfaces. Qi1 surfaces are drained well-developed, deeply incised (4 to 6 m) QTsl Qi2 Qy1 Qi2 tributary channel networks. Underlying basin fill deposits are occasionally exposed along Qy2r Qy1 Qi2 Qi1 Late to early Holocene river terrace deposits - Deposits associated with slightly higher Qi2 QTsp Qy1r some ridge slopes and along wash banks. Well-preserved Qi1 surfaces have moderately to Qy QTsl terraces that represent either higher elements of the early historical floodplain or remnants of 2 Qi2 tightly packed cobble, boulder, and pebble lag. Surface clasts are strongly to very strongly Qi3r Qy2 QTsl Qi2 QTsp older Holocene aggradation periods. These fine-grained terrace deposits commonly have Qi1 varnished and often have thin carbonate rinds. More eroded, rounded Qi1 surfaces are Tsp Qi2 ' Qi3r 2 been disturbed by plowing or cattle grazing. When undisturbed, Qy1r deposits are densely Qy 5 Qys Qy3 Tsp 5 characterized by course pebble, cobble and boulder lags with exposed carbonate horizons. Qy1 Qi2 ° ' vegetated by mature mesquite trees (mesquite bosque) and tall grasses. Soil development is

Qi1 1

5 Qy1 3 Where well preserved, Qi1 soils are strongly developed with a dark red (5-2.5 YR), heavy clay 5

° moderate and surface color ranges from dark yellowish brown to brown (10 to 7.5 YR 4/4). 1 Qi3r QTsl Qi2 argillic horizon, subangular blocky to prismatic structure, and stage III-IV carbonate 3 Qi2 Due to the dense vegetation input of organic matter at the surface is high and often results in accumulations. Qi3r Qys QTsd Qy2 a thin (< 10 cm) organic soil horizon. A light dusting (incipient stage I) calcium carbonate Qi2r Qi2 Qi Qi3r QTsl 2 QTa accumulation is evident on the undersides of some buried clasts. Qy1r surfaces stand up to 7 Qi3r Qys QTsl meters above the active channel in highly incised locales and typically are located less than Early Pleistocene alluvial fan deposits - Remnant surfaces of deeply dissected relict alluvial Tsp Tsp Qy2 0 Qyaf Qi2 0 Qo 0 Qi3r Qys 0 1.5 m higher than adjacent Qy2r surfaces. These terraces are typically covered with fans found only on the upper piedmonts. Where preserved Qo soils are strongly developed 0 0 1 1

3 Qys 3 fine-grained floodplain deposits, but relict gravel bars and lenses are common. with a distinct dark red (5-2.5 YR), heavy clay argillic horizon and subangular blocky to 5 Qyaf 5 3 Qi2 3 Qy2r QTsl prismatic structure, and stage III-IV carbonate accumulations. Rounded eroded Qo ridges are Qyaf Qi2 Qi2r white from exposed carbonate layers. Slopes are very coarse with pebble, cobble and Qy2 QTsl QTsp Qi2 Late Pleistocene river terrace deposits - River terrace deposits found on ridge ends along the Qi1 boulder lag. In some exposures along Sheep Wash it appears that this Qo deposit grades Qi2 Qi3r San Pedro River. Qi3r deposits are thin (< 2 m) and composed of rounded to well-rounded Qi2 into basin fill unit Qsf. In other exposures along this wash, unit Qo is clearly courser than the Tsp QTsl gravels, cobbles, and finer-grained sediment. Qi3r soils are moderately developed, with QTsc Qi2 underlying Qsf. Qi2 orange to reddish brown clay loam to light clay argillic horizons and stage I-II carbonate Tsp QTsl Qi2 Qi2 accumulation. Qi2 Qi2 Early Pleistocene alluvial fan deposits - Coarse gravelly to very coarse cobble and Qys QTsp Qi2 QTa boulder deposits that erosionally overlie basin-fill sediments and form the upper parts of high, Qi2 Middle to late Pleistocene river terrace deposits - River terrace deposits found on scattered QTsl broad to very rounded ridges of relict alluvial fans. QTa deposits are composed of very Qi2r hilltops along the San Pedro River. Qi2r surfaces are the highest remnant river terraces in QTsl Qi2 poorly-sorted angular to sub-angular sand, pebbles, cobbles, and boulders common in alluvial Qys QTsc this area, approximately 20 m above the valley floor. Qi2r deposits are composed of rounded

0 0 fan deposits. High standing rounded ridges are composed of carbonate-cemented 0 Qy2r Qy2 Qi2 0 to well-rounded boulders, cobbles, and gravels, with finer-grained sediments. Qi2r surfaces 0 0

0 Tsp 0 fanglomerate cap which armors the underlying, less indurated basin-fill sediment. In the

3 Qy3r 3

5 5 are well-preserved and have well-developed soil with reddened (5 YR), clay argillic horizons,

3 Qy1 3 Qi3 northwest corner of the quadrangle.QTa is derived from the granites of Texas Canyon and Qy2 Qyaf Qo with obvious clay skins and sub-angular blocky structure. Qy2 forms deeply dissected, rounded ridges with a grussy gravel surface mantel, and a few Tsp d Tsp QTa scattered pebble and cobble lags. Exposures of QTa deposits are generally poor, and are Qy1 Qy1 Qy1 Qi3 Pleistocene river deposits, undifferentiated - a moderately thick sequence of coarse, commonly the highest standing deposits in the proximal piedmont. QTsc Qir Qi2 poorly-sorted San Pedro River deposits and consolidated, moderately to well-sorted, channel Qy3r conglomerates. Qy1 Quaternary to Tertiary Basin Fill alluvium QTsd Tsp Qy2r Qi2 Piedmont alluvium and surficial deposits Qy1 Qy1 Pliocene to early Pleistocene St. David Formation - Unit QTsd is essentially equivalent to the Qy2 QTsd Saint David Formation. The basin fill was mapped with this unit when (1) it was not possible Qi1 Modern stream channel deposits - Active channel and gravel bar deposits composed of very to map individual facies at a scale of 1:24,000, (2) colluvium from overlying units obscured the Qi2r Tsp Qyc 0 Tsp 0 poorly-sorted sand, pebbles, and cobbles with some boulders to moderately-sorted sand and basin fill, or (3) access was limited. The total thickness of QTsd deposits is not known. Unit 0 Qi2 0

0 Qi3 0 Qy1 Qi3r Qi2 9 9 pebbles. Channels are generally incised 1 to 4 m below adjacent Holocene terraces and

2 2 QTs is composed of the following five basin fill units.

5 Qi3 5 3 QTa 3 alluvial fans, but may be incised as much as 30 m below adjacent Pleistocene deposits. Qy3 Qi2 Channel morphologies generally consist of a single thread high flow channel or multi-threaded Qyaf low flow channels with gravel bars. Channels are extremely flood prone and are subject to Pliocene-Pleistocene basin fill alluvial fan deposits - Piedmont alluvial fan deposits on the Qsf middle piedmont consisting of tabular sands and gravels, often stacked. Occasionally Qy3r deep, high velocity flows in moderate to large flow events, and severe lateral bank erosion. paleosols developed on top of one bed before the next was deposited. On the lower Qy2 Qi3r piedmont this unit is composed of thinly-bedded distal fan sands and gravels. Excellent QTa Qi3 Qi2 Latest Holocene alluvium - Low active terraces found only near the San Pedro River along exposures of this unit can be seen along Sheep and Dragoon washes. This unit roughly d Qi3r Qo Qi1 Qi2r Qi2r QTsd Qy3 Qi2r Qi2 incised portions of major piedmont tributary streams. These low lying terraces were part of correlates to upper Saint David Formation. Interfingers with units QTsp and QTsc near its QTsd Qy1 Qy3r Qy1 unit Qyc prior to the late 19th-early 20th century incision. Unit Qy3 terrace surfaces typically base. Qi2 Qy2 Qi2 QTsc Qi3r are mantled with pebbles, sand, and finer sediment. Terraces have planar surfaces, but small Qy2 channels are common. Adjacent channels are extremely flood prone and potential lateral bank Qy1 QTa QTsd Qi2 Qy1 Pliocene-Pleistocene floodplain fan deposits - Piedmont floodplain deposits composed QTsd Qy1 erosion is severe. Qy3 terraces may change significantly during high flow events. 0 0 QTsp 0 Qi2r Qy2 0 mainly of paleosols, both vadose and hydromorphic paleosols. Includes interbedded 0 0 8 8

2 Qy1 2 tabular sands and gravels (QTsf), marls, pond limestones and interbedded red and green 5 QTsl Qy2 Qi3 5 3 Qy2r Qy2 Qi1 3 Qi2 Tsp Qy1 Late Holocene alluvium, active fan deposits - Qyaf deposits consist of active alluvial fan clays (QTsl), and channel conglomerates (QTsc) where not mapped separately. Roughly Qi2 Qi2 Qi2 Qi2 Qyaf deposits in the San Pedro valley. These deposits have distributary drainage patterns and are correlates to middle Saint David Formation. Interfingers with units Qsf in the upper Qi3r Qyaf Tsp QTsd QTsl extremely prone to flooding and channel migration. Sediments are unconsolidated and consist sections. Qy3r Qy2 Qy2 Qy1 of very poorly sorted sand to cobbles. Vegetation includes small mesquite trees, shrubby Qy1 Qy2 Qi3 Qy1 acacia, prickly pear, and medium creosote. Qi2 QTsd Tsp Pliocene-Pleistocene lacustrine deposits - Limestones, marls and interbedded red and QTsl Qi2 QTsl Tsp Qi3r Qy3 green clay. Interbedded with, and part of, unit QTsp. Correlative to middle Saint David Qys Qi2 Qy1 Qyc Qy2 QTsl Late Holocene alluvium - Young deposits in low terraces and small channels that are part of Formation. Qy3r Qi2 QTsl Qy2 the modern drainage system, and alluvial fan surfaces that were active prior to San Pedro Qy2 Qi3r Qy1 River incision. Includes Qyc where not mapped separately. Along larger drainages, Qy2 Pliocene-Pleistocene channel conglomerates - Piedmont channel conglomerates Qi2 Qy1 Qy2 Qi2 sediment is generally poorly to very poorly-sorted sand, pebbles, cobbles, and boulders; Qy3r QTsc Qy1 Qy3 Qy3 Qy1 composed of consolidated, matrix supported, moderately to well-sorted, sub-angular to 0 Qy1 0 terrace surfaces typically are mantled with pebbles, sand, and finer sediment. Qy2 alluvial fan 0 Qi3r Qyaf 0 0 0 Tsp QTsl " rounded pebble, cobbles and sand. Generally this unit was found within QTsp but at many

7 Qy3r 7 Qy2r Qyc Qy1 0 deposits consist predominantly of moderately sorted sand and silt, with some pebbles and

2 Qy1 2

Qi1 3

1 ' 5 Qyc Qyc Qyc Qy 5 different elevations. Just east of the town of Saint David this unit is found at the base of 3 Qyc 3 " Qi2 Qi1 2 cobbles bar deposits. Channels on middle and upper piedmont areas generally are incised

0 Qy3 Qy1 Qy1 Qi1 5 Qys Qy3 ° 3

' QTsp and directly on top of and interfingered with unit Tsp. In other areas it is found within

QTsd 1 2 Qy3 Qy3 less than 1 m below adjacent terraces. Channels in the lower piedmont are incised up to 30 Qi1 Qy1 3 5 Qi2 Qi1 Qi1

° QTsp. And in some places these channel deposits were mapped within Qsf.

1 m below adjacent Pleistocene fans. Channels and alluvial fans within the San Pedro River 3 571000 572000 573000 574000 575000 576000 577000 578000 579000 580000 581000 582000 valley are incised up to 4m. Channels are flood prone and may be subject to deep, high 110°15' 110°12'30" 110°10' 110°7'30" velocity flows in large flow events. Potential lateral bank erosion is severe. Channel Pliocene playa deposits (~3.4 to ~5 Ma) - Unit Tsp is composed of red (5 to 10 YR) clay morphologies generally consist of a single-thread high flow channel or multi-threaded low flow Tsp and silt with minor interbedded sand and occasional gypsum deposits. This unit channels with gravel bars adjacent to low flow channels. Flood flows may significantly change SCALE 1:24,000 Arizona Geological Survey correlates to the lower Saint David Formation and represent playa deposits of a closed channel morphology and flow paths. Local relief varies from fairly smooth channel bottoms to basin. Topographic base from USGS 1:24,000 scale quadrangle series. 1 0.5 0 1 Miles 416 W. Congress Street, Suite 100 ^ Tucson, AZ 85701 undulating bar-and-swale topography that is characteristic of coarser deposits. Terraces have North American Datum of 1983 (NAD83). Projection and MN planar surfaces, but small channels are common. Alluvial fans are generally isolated from 1,000-meter grid: Universal Transverse Mercator, zone 12. (520) 770-3500 www.azgs.az.gov active flow except for the incised channels not mapped separately. Unit Qy2 has no to weak 1 0.5 0 1 Kilometers soil development. 10½º 0 1000 2000 3000 4000 5000 Feet

contour interval 20 feet Mapping Responsibility Unit Correlation 2006 MAGNETIC NORTH DECLINATION 110°15' 110°12'30" 110°10' 110°7'30" ' ' 0 0 ° ° 2 2 3 3 Cochise County Location Index Map Mapped Area Shown in Blue Adjoining 7.5' Quadrangles 110°30' 110°15' 110°0' 109°45' 109°30' 109°15' 109°0' Quadrangle Location Shown in Blue 110°22.5' 110°15' 110°7.5' 110°

WILDHORSE MOUNTAIN DEEPWELL RANCH " " 0 0 3 3

' ' Map Symbols 7 7 5 5 ' ° ° 5 ' 1 1 1 5

DRAGOON 3 3 ° GALLETA FLAT EAST SAN PEDRO RANCH 1 10 2 ° 3 2 accurate contact 3 ¦¨§ ¤£186

° approximate contact COCHISE ° 2 2 3 3

' Youberg concealed contact 0 ' °

0 BENSON 2 ° 3 2 3 BENSON SAINT DAVID KNOB HILL

181 ' £ ' 5 ¤ ' '

90 5 . . ¤£ 5 5 2 2 5 5 5 ° ° 5 ° ' ° 1 1 1 5 ' 1 3 3 3 4 5 3 ° 4 1 ° 3 1 3 ¤£82 TOMBSTONE MCGREW SPRING LAND HABERSTOCK HILL SIERRA VISTA ¤£191 ' 0 ' £80 3 Saint David 7.5' 0 ¤ °

3 HUACHUCA CITY FAIRBANK TOMBSTONE 1 ° 3 Quadrangle is located 1 3 BISBEE in western Cochise County. 110°22.5' 110°15' 110°7.5' 110° Cook and Youberg

¤£92 DOUGLAS " " 0 0 3 3 ' ' 2 2 5 5 ° ° 1 1 110°30' 110°15' 110°0' 109°45' 109°30' 109°15' 109°0' 3 3 Arizona Geological Survey 110°15' 110°12'30" 110°10' 110°7'30" DGM-48 (Saint David), v. 2.0