DIGITAL GEOLOGIC QUADRANGLE MAP FORT DOUGLAS QUADRANGLE, GEOLOGIC MAP OF THE FORT DOUGLAS QUADRANGLE, NEWTON, POPE DGM-AR-00298 AND JOHNSON COUNTIES, ARKANSAS Geology By Angela K. Braden and James M. Smith Digital compilation by Jerry W. Clark 2005 Arkansas Geological Commission, Bekki White, State Geologist Correlation of Map Units (Lower , Morrowan) - The A Hale Formation consists of two Members; the Prairie Grove o Member and the underlying Cane Hill Member. Approximately Ùbl Ùa 200-360 ft. (60-109 m) thick. Ùbm Ùbm 10 Prairie Grove Member - A fine to coarse-grained quartz Ùhp 9 Ùbu Ùhp sandstone with varying amounts of carbonate, crinoidal Ùbu Ùbu Qat Qls Holocene and Ùb o Quaternary fragments and quartz pebbles. Reddish-gray to brown or l Ù Pleistocene Ùbu a mottled on fresh surfaces but weathers dark reddish-brown. Ùhp Ùbl Ùbl Unconformity Bedding varies from thin to massive and exhibits a rounded Ùhc Ùbm weathering profile. This unit often contains cross-beds,

Ùbm Ùa Atokan liesegang bands, and a pitted surface that is referred to as

o honeycomb weathering. The base of the Prairie Grove Member 6 Qls Ùa Qo at Ùbu contains a fossiliferous quartz pebble conglomerate that

8 contains clay drapes, limonite pebbles, and clasts of shale,

Ùhc Ù siltstone, and sandstone. This unit becomes fairly thick along

bu Ù bm Hurricane Creek and has a natural bridge at the top of the Ùhp 8 o o unit. The Prairie Grove is a prominent bluff former throughout

o 12 Ùbu Ùhp the quadrangle, and in the southern part of the quadrangle 30 12 33 Unconformity

this unit sometimes forms a double bluff. It is becoming o 6 Pennsylvanian

Ùhp 3 o Ùbu Ùbl increasingly difficult to differentiate the Prairie Grove Member o Morrowan Ùbu 21 S o o due to additional sandstone packages in the Hale Formation Parker Ridge Monocline e Qls Ùbl and the lower part of the Bloyd Formation in the southern half Ùbl Ùhp

22 of the quadrangle. The Prairie Grove Member is unconformable o Ùbm with the Cane Hill Member. Approximately 40-80 ft. (12-24 m) Ùbl Unconformity thick. 29 Cane Hill Member - Consists of a gray to black fissile clay Ùbl 20 Ùh o Ùhc c to silty shale in the lower portion that contains iron nodules 22 and small limonitic box work fragments. The upper portion o 12 o f Ùbu Ù consists of thin-bedded, ripple-marked, micaceous siltstones 23oo a Unconformity Ùbl Ùhc Qls Mp and sandstones. Varies from black to dark-gray on fresh surfaces and light-gray and light-orange-brown on weathered

Mp Chesterian surfaces. Trace fossils and lycopod fragments are abundant. Qat This unit can form steep slopes but is susceptible to slope

Ùbu o5 failure creating landslides. The Cane Hill Member is 31 Ùbm unconformable with the Pitkin . Approximately 160- o Ùbu 280 ft. (48-85 m) thick. o Ùbm 7 11 Ùbl 11 Mp

Ùbm o Pitkin Limestone (Upper Mississippian, Chesterian) - A fine 12 o Mp

Ùbu Ùbu o Ùhc Ùhp to coarsely crystalline often fossiliferous limestone containing o 33 Ùa

4 18 31 crinoidal fragments, Archimedes bryozoans, gastropods, coral o oo

e 5 (rugose and colonial), and ooliths. The limestone beds in the S o19 Ùbm top of the formation are sometimes sandy. Varies from light- gray to dark-gray on fresh surfaces, but usually weathers light o o Ùbu Description of Map Units or medium-gray and is thin to massive-bedded. Often has a Ùbm Ùbl 22 petroliferous odor on freshly broken surfaces. Black clay Ùbl shale (occasionally interbedded with limestone) occurs at the

Ùbl top of the Pitkin just beneath the Cane Hill Member of the Ùa Landslide deposits (Quaternary) - Mostly blocks of sandstone Qls derived from Morrowan units. Some shale slopes in the Cane Hale Formation. Sometimes this black shale contains crinoidal

Ùhp o Hill Member and in the Lower part of the Bloyd Formation are columnals. Only the uppermost portion of the Pitkin is

10 6 particularly susceptible to failure. exposed in a tributary to Hurricane Creek and a tributary to o o Piney Creek. Approximately 2 - 120 ft. (5 - 37 m) thick. 6 Alluvium and terrace deposits (Quaternary) -

Qat Unconsolidated clay, silt, sand and gravel including deposits

Ùa on one or more terrace levels of local streams.

Ùhp Ùb o l Atoka Formation (Middle Pennsylvanian, Atokan) - 6 8 f Ùa Consists of black to tan shales, interbedded with very thin to

o thin ripple-bedded micaceous siltstones, and thin to medium

bedded, fine to very fine-grained sandstones with sub-angular to sub-rounded quartz grains. The sandstones are tan to buff o colored on fresh and weathered surfaces and contain clay Stratigraphic Section 5 f pebbles, liesegang bands, horizontal trace fossils, and cross- Ùa Qat beds. Occasionally the sandstones contain pebble

o15 t n

l conglomerate zones with external molds of fossils. The o S u ti a m a F sandstones vary from 10 - 20 ft. (3 - 6 m) thick. This contact e e

Ùbu t g m 12 k is tentative and will be resolved with future mapping. s a r o e y t o e Ùb

r Ùbm l Ùbu Approximately 40 - 300 ft. (12 - 91 m) thick. S S F 15 C o r 400 a o 1300 g Bloyd Formation (Lower Pennsylvanian, Morrowan) - In this Ùbu 5 u Ùbm

18 o S 7 quadrangle the individual members within the Bloyd

Formation cannot be recognized because its limestone units 25oÙbl S 1200

15o Ùbl (Brentwood and Kessler ) are either missing or have

o become shaly and sandy. There are no other "marker zones" Atoka Formation

to divide the section into the recognizable members known 1100 Atokan Ùbl Ùbu o 5 Ùhc from the type section in northwest Arkansas. Therefore the Bloyd Formation is divided informally into lower and upper Ùhc 1000 7 Qat parts (Hudson et al., 2001) separated by the "middle Bloyd 300 5 sandstone" (Zachry and Haley, 1975). Approximately 480-760

o ft. (144-233 m) thick. S 900 o Upper part - Consists of thin ripple-bedded to thick

10 Ùbu Ùbu micaceous sandstones interbedded with clay to silty shales. Upper part o 10 o Ùa The sandstones consist of fine to coarse-grained sub-angular

Ùbl 800 o to sub-rounded quartz. They are light- brown to gray on fresh

20 surface but weather dark-gray. The shales are dark-gray to 9 o black on fresh and weathered surfaces. This interval contains 700 "middle Bloyd Bloyd o Q Ù 4 Mp ls hc Ùhp many trace fossils and load features. Approximately 200 - 320 200 ft. (60 - 98 m) thick. sandstone" Formation

Ùbu "middle Bloyd sandstone" - A thin to massive, medium to 600 Pennsylvanian

Ùbm S coarse-grained, cross-bedded quartz or iron-cemented 13 21 o sandstone with sub-angular to sub-rounded quartz grains. o 500 Reddish, gray, or light-tan on fresh surfaces but weathers Lower part Ùhp o brown to orange-brown due to iron content. The cross-bedded Ùbl Morrowan 30o e packages can be up to three feet thick and occasionally

in 400 o 12 cl "overturned". Contains abundant lycopod fossils and rounded no Mo Qat quartz pebbles. This sandstone forms a prominent bluff 100 Prairie Grove 23 b

no throughout this quadrangle and separates the upper from the 300 Member s K

Ùa Mp dow lower part of the Bloyd Formation. A pebble clast

Ùbl Mea conglomerate is present at some localities at the base of this Hale Ùbl 200 Cane Hill S sandstone. In the southeastern corner of the quadrangle the Formation Ù c o

h Qat Ù u Member

Q s b Ùbu "middle Bloyd sandstone" displays spheroidal weathering

Ùbl l 6

o o creating rounded columns. This along with a maze of enlarged 100

4

Ùbu Ùa o 9 Ùbl joints creates an outcrop known as "Buzzards' Roost". Just Mp o across the drainage is a natural bridge known as "Rainbow

Qls o 0 ft. 0 m. Pitkin Formation 20 Rock”. The "middle Bloyd sandstone" is unconformable with

e 14 o e the lower part of the Bloyd Formation. Approximately 80-120 5 Miss.

15 Chest.

ft. (24-37 m) thick. o Lower part - Consists of interbedded very thin to thin o 11 Ùbl ripple-bedded micaceous siltstones and sandstones that are 3 fine to medium-grained interbedded with black clay to silty clay shale limestone sandstone shales. Throughout the lower portion is black fissile clay to silty shales and thin sandstones interbedded with thin to thick-bedded fossiliferous carbonate to sandy carbonate layers. Thin pebble conglomerates are present within the silstone and calcareous interbedded Ùbm interbedded shales and sandstones. The carbonate zones vary silty shale sandstone sandstone from red to gray on fresh and weathered surfaces and can be and siltstone Ùa mottled. Sometimes the fossiliferous sandy zones look "rotten" Ùhp due to decalcification. The quartz grains are medium-grained unconformable surface and sub-angular to sub-rounded. This unit contains abundant trace fossils and loading features. The contact between the lower part of the Bloyd Formation and the Prairie o9 Ùbm Ùa Grove is placed below a shaly layer conformable with the o Ùbl underlying massive calcareous sand of the Prairie Grove 5 Member of the Hale Formation. Approximately 200-320 ft.

(60-98 m) thick.

o7 Ùbm o Ùhc Ùhc 7 o Ùbu 4 Ùhp

Ùbu o 4 References Ùhp Symbols Joint Frequency 12 Ùbm Ùbl Ù Ù Qat o hc bm Ùhp Ùhp Ùbl N Braden, Angela K., and Smith, James M., 2004, Geologic map Ùbl Ùbl o35 Ùhc Contact 0 37 of the Deer Quadrangle, Newton County, Arkansas: o Qat 340 20 Contact - inferred Arkansas Geological Commission Digital Geologic Map A' 320 40 DGM-AR-00217 1 sheet. D Fault Haley, Boyd R. 1972, Geologic map of the Treat Quadrangle, U U-upthrown 300 60 15-minute series: Arkansas Geological Commission D-downthrown Geologic Worksheet, 1 sheet. Hudson, M.R., Murray, K.E., and Pezzutti, D, 2001, Geology 280 80 Fault - Inferred of the Jasper Quadrangle Newton and Boone Counties, Arkansas: U.S.G.S. Miscellaneous Field Studies Map MF- 2356. Fault - Concealed 100

260 Stone, Charles G., 1956, The geology of T.12 N., R.21 W., Johnson County, Arkansas: University of Arkansas M.S.

Monocline 120 S 240 Thesis, 35 p. o Zachry, Doy, L., and Haley, Boyd, R., 1975, Stratigraphic Strike and dip relationships between the Bloyd and Atoka Formations 10 220 140 of inclined bedding N=59 (Pennsylvanian) of northern Arkansas: in Contributions 200 180 160 to geology of the Arkansas Ozarks, Arkansas Geological Commission Miscellaneous Publication 12, p. 96-106. Rose diagram of strike frequency of joints Zachry, Doy, L., and Manger, L., Walter, 1998, Morrowan recorded within the Fort Douglas Quadrangle. (Lower Pennsylvanian) reservoir stratigraphy, southern Ozark region northern Arkansas in Fort Smith Wheeler Knob Bald Knob Geological Society Morrowan Reservoir Stratigraphy Field Trip Guidebook, November 12-13, 17 p. A A' Parker Ridge Meadows Knob 2000 Fault Ùa 2000 Ùa Ùa 1800 Sugar Creek Fault Bear Creek Meadows Knob Fault 1800 Hurricane Ùbu Ùbu 1600 Ùbu 1600 Creek Ùbm Acknowledgments: This map was produced for STATEMAP, Ùbm Ùbm Cooperative Agreement Award 04HQAG0038, a matching- 1400 Ùbu funds grants program with the US Geological Survey under Ùbl 1400 Ùbm Ùhp Ùhp Spring Creek The National Cooperative Geologic Mapping Program. Special Ùbl Ùhp 1200 Ùbl Ùhp thanks to the U.S. Forest Service and to private landowners Ùbl Ùhp Ùbl 1200 who graciously allowed access to their property. Ùhp Ùhc Qat > Disclaimer: This map was prepared in a digital format using 1000 > Ùhc 1000

Ùhc ArcView 9, ArcGIS 9 software on computers at the Arkansas

Mp > Geological Commission. The Arkansas Geological Commission > Ùhc Ùhc 800 Mp ? Mp Ùhc 800 does not guarantee the accuracy of this map especially when used on any other system or with any other software. As

Mp Mf Mp Mf ? Mf mapping continues and is refined, the data presented on this 600 Mf Mf 600 map may be updated. For the latest edition of this publication please contact our office. SEA LEVEL SEA LEVEL Scale For information on obtaining copies of this map and other Horizontal: 1 inch = 2000 feet Arkansas Geological Commission maps and publications call: Publication Sales Vertical: 1 inch = 500 feet (4X: Exaggeration) 501-296-1877 Revised June, 2006