BUFFALO

NATIONAL RIVER

BUFFALO

NATIONAL RIVER

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C

Figure 3. A, Photograph of bottom of sandstone bed in Cane Hill Member of the Hale Formation (hc) 

showing rip-up clasts of shale and siltstone as well as casts of wood fragments in a sand matrix. Fingernails 

are 0.5 inch (in) long. Photograph by M. Hudson, 2017. B, Photograph of bryozoan Archimedes in Pitkin 

Limestone (Mp) where observed in the northwesternmost drainage of the quadrangle, west of Dinsmore. 

Fayetteville Shale (Mf) that underlies Pitkin Limestone in this area is only about 60 feet thick. Green pen cap is 

2.5 in. long. Photograph. by K. Turner, 2016. C, Photograph of Hindsville Member of the Batesville Sandstone 

(Mbv) showing angular to subrounded clast of weathered chert in fossiliferous limestone matrix. Hammer head 

is 6.5 in. long. Photograph by M. Hudson, 2016.

A

B

Figure 1. Location of study area in northern Arkansas, adjacent to the western part of Buffalo National River. 

Previously published U.S. Geological Survey (USGS) geologic maps are highlighted in yellow . This report in 

dashed blue outline. USGS Investigations Map 3314 in dashed green outline. Lower regional map (modified from 

Hudson, 2000) shows geologic and selected physiographic provinces of Arkansas and adjacent areas with the 

Osage SW 7.5' quadrangle highlighted as a yellow box. The Ozark Plateaus region includes Salem and 

Springfield Plateaus and Boston Mountains physiographic provinces.

River

Buffalo

¬«103

¬«21

OZARK DOME

94° 92° 90° 

MISSISSIPPI 

 EMBAYMENT

ARKANSAS

ARKOMA BASIN

Ouachita Mountains

Boston Mountains

MISSOURI

TENN

MISS

OKLA

KAN

St. Francois

SALEM 

PLATEAU

Springfield

Plateau

Mountains

37°

35°

33°

TEXAS

Harrison

SNOWBALL

OSAGE NE

OSAGE SW

GAITHER HARRISON

JASPER WESTERN

GROVE

MT.

JUDEA

EULA BOXLEY MURRAY

HASTY

PARTHENON

PONCA ST. JOE MAUMEE

MARSHAL

SIM 3416

(Turner and

Hudon, 2018)

SIM 3360

(Hudson and

Turner, 2016)

MF 2412

(Hudson and

Murray, 2003)

MF 2356

(Hudson and

others, 2001)

OFR 98–116

(Hudson, 1998)

SIM 2847

(Hudson and

Murray, 2004)

SIM 2921

(Hudson and

others, 2006)

SIM 3314

(Hudson and

Turner, 2014a)

SIM 3074

(Hudson and

Turner, 2009)

SIM 3134

(Turner and

Hudson, 2010)

36°

36°15'

35°52’30”

36°07’30”

93°22'30” 93°15' 93°07'30”

93°30' 92°45' 92°37'30”

93°

92°52’30”

BUFFALO

NATIONAL

RIVER

43

21

7

65

0

0

5 MILES

5 KILOMETERS

N

S

W E

S

N

W E

N

W E

S

A

C

B

Figure 5. Structural data for the Osage SW quadrangle. Number of 

data are “n”. A, Stereoplot of poles and orientation density contours 

for faults in the quadrangle. Contour levels are multiples of standard 

deviations. B, Subset of striated faults with known slip sense. Arcs 

and dots are lower hemisphere projections of fault planes and their 

slip lines, respectively. Black, gray, and white symbols indicate 

normal, strike-slip, and reverse slip sense, respectively. Small 

arrows show movement sense of hanging wall block. Red-filled 

large, medium, and small circles represent orientation of maximum, 

intermediate, and least principal paleostress axes, respectively, from 

paleostress analysis of Angelier (1990), excluding three faults with 

large misfits (indicated by two grayed symbols and one white 

symbol). Large arrows show azimuth of least horizontal 

compression. C, Rose diagram of strike frequency of joints recorded 

within the map area. Database of fault, joint, and deformation band 

measurements are available for download from Turner and Hudson 

(2018) as a ScienceBase data release at 

https://doi.org/10.5066/P98DH5SP.

n = 52 Normal faults

n = 1,038

EXPLANATION

Multiples of standard

deviation

1–1.99

2–3.99

4–5.99

6–7.99

8–9.99

1600

1500

1700

1800

1400

1900

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2000

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2000

Dry

Fork

 Whitely

 Creek

Kenner Creek

Kenner Creek

Buffalo

River

Clark

S

Cr

weden

Creek

Dry Creek

Dry

Fork

Whitely

Creek

Kenner Creek

Kenner Creek

Buffalo

River

Clark

Cr

Sweden

Creek

Dry Creek

93°22'30" 93°30'

36°

36°7'30"

A

A'

B

B'

Dinsmore

Stoverville

PICKLE

FAULT

HOLLOW

Cockran Hollow

COMPTON

COMPTON

FAULT

FAULT

LOGAN MOUNTAIN FAULT

Logan

Mountain

Grogans Hollow

Pickle Hollow

Digital Elevation Model base from the U.S. Geological Survey, Earth Resources Observation and Science (EROS) Center, 2003

North American Datum of 1927 (NAD 27), Universal Transverse Mercator (UTM), zone 15N

ADDS

HOLLOW

SYNCLINE

GROGANS

CREEK

MONOCLINE

0 1 MILE

0 1 KILOMETER

Normal fault—Bar and ball on downthrown

block. Long dash, location approximate,

short dash, location concealed

Structure contour elevation—Hachures point

to closed areas of lower values. Contour

interval 100 feet 

Base of upper part of Bloyd Formation (Pbu)

Top of the Boone Formation (Mb)

Monocline

Line of section

Syncline

EXPLANATION

1800

1500

Deformation bands

Fault site—Fault observed, no measurements

Fault site—Fault observed, measured, and slip

sense determined; measurements represented 

in figure 5

Normal

Strike-slip

A A’

Figure 4. Shaded-relief digital elevation map of the U.S. Geological Survey Osage SW 7.5' 

quadrangle with locations of structural features, structure contours (100-foot interval), and sites 

where faults were observed. Where determined, slip senses for faults at sites are indicated as 

normal (rake 90o to 60o) and strike-slip (rake 29o to 0o). Also shown are locations where deformation bands were observed.

Sandstone

Cross-bedded sandstone

Ripple-bedded sandstone

Calcareous sandstone

Dolomitic sandstone

Limestone

Dolostone

Shale

Siltstone and shale

Chert

Phosphate nodules

Oolites

Unconformity

Bryozoans

EXPLANATION

Figure 2. Representative stratigraphic column for Paleozoic rocks in the map area based on maximum 

thickness of units. North American stage names for Pennsylvanian and Mississippian units are from 

McFarland (1988, 2004). Division of the Pennsylvanian and Mississippian subsystems follows Heckel and 

Clayton (2006). Ss, sandstone; Ls, limestone; K, Kinderhookian.

Boone

Formation

(main body)

(Mb)

Fayetteville

Shale

(Mf)

Batesville

Ss (Mbv)

St. Joe Ls

Member (Mbs)

Cane Hill

Member

(hc)

Prairie

Grove

Member

(hg)

Hindsville Limestone Member

(not mapped separately)

Bloyd Formation Upper

part

(bu)

Hale Formation

Lower

part

(bl) Brentwood Limestone Member

(not mapped separately)

Fernvale Ls (Of) Meramecian Osagean Provincial Series

Ordovician Mississippian Pennsylvanian (part) PERIOD

EPOCH

Pitkin Limestone (Mp)

"Middle Bloyd sandstone"

(not mapped separately)

Upper part of

Everton Fm (Oeu) Morrowan Chesterian

Wedington Sandstone Member

(not mapped separately)

Atokan

Middle

Pennsylvanian Lower Pennsylvanian Upper Mississippian Middle Mississippian Lower Mississippian

Atoka

Formation

(a)

K

Upper

Middle

200

100

400

500

300

700

600

800

900

1,000

1,100

1,200

1,400

1,500

1,300

400

300

200

100

0 0 

METERS FEET

B B'

North SOUTH

VERTICAL EXAGGERATION x2

FEET METERS

1,000

2,000

2,500

500

1,500

300

400

600

700

200

500

Mp

Ou

Oeu

Mbs

hc

hg

a

bu bl

Mbv

Qty

Of

Mb

Mf

Oeu

Qty

Oeu

Mbs

hc

hg

bl

bu

Mbv

Mf

Mbs

Mbv

Mf

a

Mb

Mb Mb

Oeu

Mb Mbs

hc

bl hg

bu

Mbv

Mf

Ou OuKenner Creek

Buffalo River

PICKLE HOLLOW FAULT

COMPTON FAULT

Qty

GROGANS HOLLOW SYNCLINE

Ou Ou

Oeu

Mbs Mb

Mbv

Mf

Mf Mp hc hc hc

hg hg

hg

bl bl bl

bu

bu

Mb

hc

hg bu

Mbv

Qty Qc

Mp

bl

Qty

Ou

Oeu Mbs

hc Mp hc

hg bl bl

Mbv

LOGAN MOUNTAIN 

FAULT

A A' COMPTON FAULT

North SOUTH

VERTICAL EXAGGERATION x2

FEET METERS

1,000

2,000

2,500

500

1,500

300

400

600

700

200

500

Maxwell Creek

Dry Creek

Sweden Creek

DESCRIPTION OF MAP UNITS

[Provincial stages for Pennsylvanian and Mississippian units are from McFarland (1988, 

2004). Division of the Pennsylvanian and Mississippian subsystems follows Heckel and 

Clayton (2006)]

Younger terrace and active-channel alluvial deposits Quaternary)— 

Unconsolidated sand and gravel of the Buffalo River and tributaries to 

the Kings River that include Sweden Creek, Dry Creek, Dry Fork, and 

Kenner Creek. Terrace deposits are principally composed of light-brown 

fine sand; smooth upper surfaces are about 20 feet (ft) above base flow. 

Gravel deposits of the active channels are composed of subangular to 

rounded Paleozoic rock clasts of mixed lithology, which are interspersed 

with bedrock exposures too small to show at map scale. Low-lying parts 

of deposit subject to periodic flooding. As thick as 20 ft

Colluvial deposits (Quaternary)—Unconsolidated deposits of subrounded to 

angular blocks as large as 20 ft in diameter, commonly in an 

orange-brown, silty clay matrix. Blocks are mostly derived from the 

basal sandstone of the upper part of the Bloyd Formation (bu) and the 

Cane Hill Member (hc) of the Hale Formation. Deposits have fan-like 

morphology and were mapped where sufficiently thick to mask typical 

ledge-flat topography of underlying bedrock. Smaller, thinner colluvial 

deposits elsewhere were not mapped. Thickness probably 10 ft or more

Older terrace alluvial deposit (Quaternary)—Unconsolidated gravel and 

sand deposit found at one locality in northwest map area adjacent to Dry 

Fork, north of Dinsmore, Arkansas. Deposit contains brown, weathered, 

subrounded to rounded Paleozoic sandstone cobbles and white, 

subangular chert cobbles in brown, silty to sandy matrix about 40 ft 

above Dry Fork. Thickness about 10 ft

Atoka Formation (Middle Pennsylvanian, Atokan)—Alternating shale, 

siltstone, and sandstone intervals underlying hills in southeastern and 

northeastern parts of map area. Where exposed, shale is fissile and dark 

gray to black. Siltstone is thin bedded with ripple cross laminations. 

Sandstone intervals as thick as 10 ft, are locally bioturbated, and vary 

between the following: tan, very fine to fine grained, ripple to planar 

bedded; white, medium to coarse grained, medium planar bedded; and 

thick, cross-bedded with sparse, white quartz pebbles. Unit is poorly 

exposed, and the basal contact was not observed in the map area. The 

inferred basal contact was placed in a poorly exposed shale interval that 

forms a topographic flat about 270–300 ft above base of upper Bloyd 

Formation (bu). Contact is better constrained on the Ponca quadrangle 

to the east where contact is placed above a coal layer about 250 ft above 

the base of the upper part of the Bloyd Formation (Hudson and Murray, 

2003). Deposits in the map area correlate with the lower part of the 

Atoka Formation farther south in the Arkoma Basin where the unit is more 

completely preserved in the subsurface (Zachry and Southerland, 1984). 

Thickness is as much as 120 ft

Bloyd Formation (Lower Pennsylvanian, Morrowan)—Interbedded 

sequence of sandstone, siltstone, shale, and limestone beds separated into 

upper and lower parts. Thickness as much as 360 ft

Upper part—Interbedded sandstone, siltstone and shale above a basal 

cliff-forming sandstone interval. Upper part of unit contains dark-gray to 

black shale and siltstone beds interbedded with ledge-forming sandstone 

beds. Upper sandstone beds are 5–20 ft thick, commonly extensively 

bioturbated, and vary from (1) orange-brown, fine to coarse grained that 

locally contain quartz pebbles; (2) medium to thick, planar bedded to 

cross-bedded; to (3) tan or olive, very fine to fine grained, ripple 

cross-laminated to planar bedded that locally contain flattened 

carbonaceous fragments. Base of unit is cross-bedded sandstone that 

generally forms prominent 20–80 ft cliffs. The basal sandstone has a 

sharp erosional base and is commonly a composite of several tabular and 

trough cross-bed sets composed of white to light-brown, fine- to 

medium-grained quartz arenite. Local concentrations of white quartz 

pebbles and casts of wood fragments are common. In the northwestern 

and eastern parts of the map area, basal interval forms a less prominent 

cliff composed of thin- to medium-bedded sandstone interbedded with 

siltstone and shale. Zachry (1977) correlated Bloyd Formation deposits 

between northwestern Arkansas and the Boxley area (south of the map 

area), and indicated that the finer grained upper parts of the unit are 

correlative with the Dye Shale Member and the basal sandstone is 

time-equivalent with the Woolsey Member of the Bloyd. Zachry (1977) 

informally designated the basal sandstone interval as the “middle Bloyd 

sandstone.” Thickness is 200–300 ft

Lower part—Dominantly shale and siltstone, with interbedded limestone 

and thin beds of sandstone. Shale and siltstone are dark gray and fissile 

to thin, ripple laminated. Sandstone is tan, very fine to fine-grained and 

thin bedded with ripple marks. Limestone is medium to thick bedded, 

red-brown and conglomeratic, with clasts containing fossil fragments and 

subrounded sandstone and siltstone. The Brentwood Limestone Member, 

at the base of the formation (not mapped separately), is a 5- to 20-ft-thick 

limestone interval varying from gray micrite to reddish-gray, coarse 

bioclastic limestone. In the type area in northwestern Arkansas, the 

Brentwood Limestone Member includes marine limestone and shales. 

Usage here follows that of McFarland (1988) and reserves the 

Brentwood Limestone Member for the limestone beds at the base of the 

unit. Unit has a gradational contact with the underlying Hale Formation. 

Forms moderate to steep slopes and is poorly exposed. Thickness 20–60 ft

Hale Formation (Lower Pennsylvanian, Morrowan)—Interbedded 

sequence of sandstone, siltstone, shale, and thin limestone. Thickness 

130–260 ft

Prairie Grove Member—Brown to reddish-brown, fine- to 

medium-grained, thick-bedded, calcite-cemented sandstone with 

interbeds of limestone. Locally contains quartz pebbles in basal 

sandstone beds. Sandstone beds are planar or cross-bedded, and 

cross-beds may have bidirectional dips. Sandstone weathers to form 

rounded surfaces with elliptical cavities as long as 1 ft. Unit contains 

some interbeds of reddish-brown, coarse bioclastic limestone. Shale 

layers separating sandstone beds are reported regionally (Southerland, 

1988), but were not observed in the map area. Unit forms steep slopes 

and is often covered by thin colluvium derived from overlying units. 

Basal contact with Cane Hill Member (hc) is unconformable. 

Thickness 30–80 ft

Qty

Qc

Qto

a

bu

bl

hc

Mp

Mf

Mbv

Mb

Mbs

Of

Oeu

Ou

Cane Hill Member—Interbedded sequence of shale, siltstone, and 

sandstone. Upper part composed of fissile to ripple-laminated, dark-gray 

shale and siltstone underlain by 15- to 30-ft-thick middle interval of 

ripple-laminated to thin-bedded, very fine grained sandstone; middle 

interval also may contain channels of massive cross-bedded, fine- to 

medium-grained sandstone that locally has shale and siltstone ripup 

clasts and wood casts (fig. 3A). Lower part of unit includes gray shale 

and siltstone underlain by a 5- to 15-ft-thick, pale-orange, very fine to 

fine- grained, calcite-cemented sandstone that is often punky and friable 

due to partial leaching of calcite. Sandstone at base of unit locally 

overlies conglomerate lenses as thick as 3 ft that contain quartz pebbles 

and subangular to subrounded clasts of sandstone, siltstone, shale, and 

limestone. Sandstone beds throughout unit locally display slumps and 

folds attributed to soft-sediment deformation. Unit unconformably 

overlies Pitkin Limestone (Mp) and Fayetteville Shale (Mf). Thickness is 

100–180 ft

Pitkin Limestone (Upper Mississippian, Chesterian)—Medium- to 

dark-gray fetid limestone. Limestone varies from micrite at base to 

coarse grained and locally oolitic near top. Limestone beds locally 

contain abundant crinoids, brachipods, corals, and bryzoan Archimedes

(fig. 3B). Basal contact with the Fayetteville Shale (Mf) is conformable. 

Pitkin generally crops out as a prominent ledge or cliff. Only present in 

the southwest and northwest parts of the map area. Thickness 0–40 ft

Fayetteville Shale (Upper Mississippian, Chesterian)—Black shale with 

interbeds of dark-gray to tan sandstone. Upper part of unit is usually 

absent, but where present in southwestern part of map, includes a tan, 

calcite-cemented sandstone as thick as 12 ft, representing the Wedington 

Sandstone Member (Purdue and Miser, 1916). Sandstone is very fine 

grained, and medium to thin, planar to ripple bedded with internal 

parallel laminations. Main body of unit is black, fissile shale that 

generally forms gentle slopes. Lower part of the Fayetteville may contain 

medium- to light-gray, fetid septarian concretions as large as 2 ft in 

diameter. Fayetteville Shale is susceptible to landslides. Unit is 

conformable with underlying Batesville Sandstone. Where overlain by 

Pitkin Limestone, Fayetteville Shale is as thin as 60 ft in the northwest 

part of the map but as thick as 170 ft in the southwest part of the map

Batesville Sandstone (Upper Mississippian, Chesterian)—Very fine to 

fine-grained, light- to medium-brown, calcite-cemented sandstone with 

interbedded limestone. Upper part is a 3- to 5-ft-thick bed of dark-gray 

fetid limestone with common crinoid fragments, but limestone is not 

always present. Main body of unit is thin to medium planar to 

hummocky beds of sandstone that are parallel laminated. Basal 

Hindsville Limestone Member (not mapped separately) is locally 

preserved and consists of 2–7 ft thick bed of gray limestone with angular 

white chert clasts (fig. 3C), inferred to have eroded from the underlying 

Boone Formation, indicating an unconformable contact. Sandstone and 

limestone commonly contain disseminated pyrite framboids that oxidize 

to reddish spots. Topographic surfaces underlain by the Batesville are 

commonly flat and may host sinkholes formed by collapse into dissolution 

cavities in the underlying Boone Formation. Thickness is 10−30 ft

Boone Formation (Middle to Lower Mississippian)—Mostly limestone and 

chert-bearing limestone that grades downward into the basal St. Joe 

Limestone Member. Formation commonly hosts caves and sinkholes. 

Total thickness is 370−410 ft

Main body (Middle to Lower Mississippian, Meramecian to Osagean)— 

Medium- to thick-bedded, chert-bearing bioclastic limestone. Limestone 

is light to medium gray on fresh surfaces and generally coarsely 

crystalline with interspersed crinoid ossicles. A 1- to 3-ft-thick bed of 

oolitic limestone is locally present in upper 10 ft of the Boone 

Formation. Dense, fine-grained limestone is present in upper one-third of 

unit. Beds are typically parallel planar to wavy. Chert content varies 

vertically and laterally within the Boone and is locally greater than 50 

percent. Chert is light to medium gray or white and forms lenticular to 

anastomosing lenses. Chert-rich horizons are generally poorly exposed, 

and are characterized by abundant, weathered chert fragments on 

hillslopes. Chert in uppermost part of unit often contains brachiopod 

molds. Basal contact with the St. Joe Limestone Member is gradational. 

Thickness 340−360 ft

St. Joe Limestone Member (Lower Mississippian, Osagean to 

Kinderhookian)—Thin-bedded, bioclastic limestone with ubiquitous

3- to 6-millimeter (mm)-wide crinoid fragments in fine matrix.

Limestone is commonly pink to red on fresh surfaces due to hematite in

matrix, but color and hematite concentrations vary with location. Thin

beds are typically wavy in form. Chert nodules are uncommon but,

where present, are tabular and reddish. Middle to lower part of unit may

contain shaley limestone interval. Base of unit is up to 1-ft-thick bed of tan

sandstone containing phosphate nodules. Unit exposed along the Buffalo

River and tributaries in southeastern map area where it unconformably

overlies Ordovician units. Thickness approximately 30−50 ft

Fernvale Limestone (Upper Ordovician)—Medium- to thick-bedded, 

coarse-crystalline bioclastic limestone. Limestone is light pinkish gray to 

medium gray on fresh surfaces and contains abundant 3- to 10-mm-wide 

cylindrical to barrel-shaped crinoid ossicles. Unit exposed along the 

Buffalo River and tributaries in southeastern map area but is interpreted 

to pinch out northward based on thickness variations seen in regional 

mapping (Hudson and Turner, 2014a). Thickness 0−30 ft

Upper part of Everton Formation (Middle Ordovician)—Interbedded 

limestone, dolostone, and sandstone. Up to 10 ft of light-gray micrite and 

limestone-cemented sandstones of the Jasper Member (not mapped 

separately) directly below contact with Fernvale Limestone in Whitely 

Creek. Below Jasper Member, unit includes 3- to 20-ft-thick, light- to 

dark-gray dolostone beds interbedded with sandstone. Carbonate beds 

are typically finely crystalline, sparsely fossiliferous, and commonly 

display crinkly laminations. Sandstone is medium to thick, 

planar-bedded, light tan to white quartz arenite that is well-sorted, 

well-rounded, fine to medium grained, and cemented by dolomite and 

(or) calcite. As much as 40 ft exposed along Whiteley Creek and 60 ft on 

the southeast side of the Buffalo River in southeast part of quadrangle. 

Unit is about 300 ft thick to the east of map area on the Ponca quadrangle 

where base of unit is exposed (Hudson and Murray, 2003)

Lower Ordovician rocks, undivided—Sedimentary rocks shown on cross 

section only

hg

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release, https://doi.org/10.5066/P98DH5SP.

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boundaries—A symposium: Oklahoma Geological Survey Bulletin 136, p. 9–17.

INTRODUCTION

This map summarizes the geology of the U.S. Geological Survey (USGS) Osage SW 

7.5-minute quadrangle (fig. 1) in the Ozark Plateaus region of northern Arkansas. 

Geologically, the area is on the southern flank of the Ozark dome, an uplift with the oldest 

rocks exposed at its center in the St. Francois Mountains in Missouri. Physiographically, 

the Osage SW quadrangle is located within a transitional area between the Boston 

Mountains to the south and the Springfield Plateau to the north (fig. 1). Exposed within 

the quadrangle is an approximately 1,460-foot (ft)-thick sequence of Ordovician, 

Mississippian, and Pennsylvanian carbonate and clastic sedimentary rocks (fig. 2) that 

have been mildly deformed by a series of faults and folds. The southeasternmost corner 

of the map area falls within the Buffalo National River—a park which encompasses the 

Buffalo River and adjacent land that is administered by the National Park Service. The 

majority of the quadrangle is privately owned land. 

Geologic mapping for this study was compiled at 1:24,000-scale in a geographic 

information system (GIS) database. The ScienceBase data release, including GIS and 

other files that support this report, is available at https://doi.org/10.5066/P98DH5SP

(Turner and Hudson, 2018). Locations and elevation of sites were determined with the aid 

of a global positioning satellite receiver and a handheld barometric altimeter that was 

frequently recalibrated at points of known elevation. Contacts were traced between 

traverses using shaded relief and slope maps derived from U.S. Geological Survey 

10-meter (m) digital elevation model (accessed January 2014, at https://nationalmap.gov)

and 1-m-resolution light detection and ranging (lidar) datasets (accessed April 2017 from

https://nationalmap.gov). Strike and dip of beds were typically measured along stream

drainages or at well-exposed ledges. Beds dipping less than 2° are shown as horizontal.

Structure contours were manually constructed at the top of the Mississippian Boone

Formation (Mb) and the base of a prominent Pennsylvanian sandstone unit that marks the

base of the upper part of the Bloyd Formation (bu) to conform to elevations of control

points and projection of bedding attitudes.

STRATIGRAPHY

The 1,460-ft-thick composite stratigraphic section and intervening unconformities 

exposed within the quadrangle record early and late Paleozoic deposition and erosion on 

the southern margin of the North American continent. Paleozoic rocks were exposed 

during Quaternary erosion associated with incision by the Buffalo River, and tributaries 

to the Kings River. 

The Middle Ordovician Everton Formation (Oeu) is a heterogeneous sandstone and 

carbonate unit that Suhm (1974) interpreted to have been deposited in barrier island and 

tidal flat depositional environments. The Everton Formation in the map area correlates 

with the upper part of the formation mapped in the Ponca 7.5' quadrangle (Hudson and 

Murray, 2003) east of the map area, which is dominantly dolomitic with the exception of 

limestone and limey sandstone beds in the Jasper Member. Following deposition of the 

Everton Formation, the area was within a shallow shelf environment where recurrent 

intervals of marine to subaerial transitions occurred throughout the Middle and Late 

Ordovician resulting in deposition and variable stripping of marine deposits (Frezon and 

Glick, 1959; Craig and others, 1984). Within the map area, the Everton Formation is 

unconformably overlain by Upper Ordovician Fernvale Limestone (Of); the St. Peter 

Sandstone and Plattin Limestone, deposits preserved between the Everton and Fernvale, 

farther east in the Buffalo River area (McKnight, 1935; Hudson and Turner, 2014a), were 

removed prior to Fernvale deposition. The Fernvale Limestone is a coarsely crystalline, 

bioclastic limestone formed in an open, subtidal environment (Craig, 1975; Craig and 

others, 1984).

Following deposition of the Fernvale Limestone, the Ozark region was mildly 

warped (Frezon and Glick, 1959) resulting in a regional unconformity above shallowly 

south-dipping Ordovician units. Above the unconformity is a distinctive phosphatenodule-bearing sandstone at the base of the Lower Mississippian St. Joe Limestone 

Member of the Boone Formation (Mbs). The sandstone is present throughout much of 

northern Arkansas (McKnight, 1935) and is interpreted as a transgressive lag deposit 

formed during Early Mississippian sea-level rise (Horner and Craig, 1984). The St. Joe 

Limestone Member grades upward from generally chert-free, red to pink, and thin bedded 

limestone into massive, chert-rich beds of the main body of the Boone Formation (Mb). 

The Boone Formation is a widespread unit throughout the region and is prone to 

karstification.

The Batesville Sandstone (Mbv) overlies the Boone Formation and is composed of 

sandstone and minor limestone. The basal Hindsville Limestone Member (not mapped 

separately) is only locally present but contains angular chert fragments probably eroded 

from the underlying Boone Formation (fig. 3C). The angular chert fragments indicate a 

depositional hiatus and period of erosion, which resulted from sea level fall following 

deposition of the Boone Formation (Handford, 1995). Sandstones of the Batesville 

Sandstone are interpreted as having been deposited in delta front and shoreface environments that prograded into the area from the northeast during Chesterian sea level rise 

(Glick, 1979).

Continued deepening of the sea associated with Chesterian transgression resulted in 

deposition of black, fissile shales of the Fayetteville Shale (Mf) that conformably overlie 

the Batesville Sandstone. Subsequent shallowing of the sea is indicated by deposition of 

the calcite-cemented Wedington Sandstone Member (not mapped separately) in the upper 

part of the Fayetteville Shale, followed by deposition of the Pitkin Limestone (Mp) 

(Handford, 1986). Throughout most of the quadrangle, Pitkin Limestone is absent; 

however, where overlain by Pitkin Limestone, Fayetteville Shale varies in thickness from 

170 ft in the southwest to about 60 ft in the northwest. Thinning of the Fayetteville Shale 

in the northwest part of the map could be explained by either a local erosional event that 

occurred prior to deposition of the Pitkin Limestone, or, alternatively, significantly less 

accumulation of the shale in the northwest part of the map. Hudson and Turner (2014b) 

report variations in Upper Mississippian strata in the Buffalo River area, which they 

suggest could be related to tectonism.

Regression of the sea in Late Mississippian resulted in a major unconformity eroded 

into Upper Mississippian strata (Sutherland, 1988; Manger and Sutherland, 1992). This 

period of erosion is supported by the pinchout of the Pitkin Limestone, thinning of the 

Fayetteville Shale, and the presence of Archimedes-bearing Pitkin Limestone clasts in 

basal conglomerate lenses of the Cane Hill Member of the Lower Pennsylvanian Hale 

Formation (hc), which were deposited above the unconformity (for example, Purdue 

and Miser, 1916; Hudson and Turner, 2016).

Sandstone and siltstone channels of the Cane Hill Member (hc) vary laterally and 

stratigraphically and are interpreted as tidally influenced successions with lenses of 

storm-deposited calcareous sandstones (Manger and Sutherland, 1992). Following a 

period of erosion, alternating thick sand-rich bioclastic facies and thin shales of the 

Prairie Grove Member of the Hale Formation (hg) represent deposition in a shelf 

environment in a series of rapidly alternating transgressive pulses (Sutherland, 1988).

The Brentwood Limestone Member of the Bloyd Formation, included here in what 

we refer to as the lower part of the Bloyd Formation (bl), is gradational with the 

underlying Prairie Grove Member of the Hale Formation. The presence of limestone 

conglomerate with sandstone and siltstone clasts and fossil fragments indicates a highenergy marine environment during deposition of part of the lower part of the Bloyd 

Formation. Sandstone and shale of the upper part of the Bloyd Formation were originally 

called Winslow Formation by Purdue and Miser (1916), and the prominent cliff-forming 

cross-bedded sandstone was correlated with the basal Greenland Sandstone Member of 

the Atoka Formation (Henbest, 1953). However, Zachry (1977) concluded that the 

cliff-forming sandstone was a time-equivalent unit with the Woolsey Member of the 

Bloyd Formation, farther west. The sandstone, informally designated the “middle Bloyd 

sandstone,” is interpreted as a braided river deposit (Zachry, 1977). The “middle Bloyd 

sandstone” is the basal interval of the upper part of the Bloyd Formation map unit (bu) 

as used here. Overlying the “middle Bloyd sandstone,” the unit consists of siltstone and 

shale mixed with fine to coarse sandstones that record deposition in a marine 

environment consistent with correlative deposits of the Dye Shale Member farther to the 

west (Zarchary, 1977). Some sandstone beds in the upper part of the Bloyd Formation are 

extensively bioturbated and contain quartz pebbles similar to pebbles in the “middle 

Bloyd sandstone” indicating a marine transgression following deposition of the braided 

river deposits of the “middle Bloyd sandstone.” A marine transgression is further 

supported by the presence of a limey sandstone with shell impressions and crinoid 

ossicles observed about 110 ft above the base of the “middle Bloyd sandstone” along the 

eastern edge of the quadrangle (1⁄4 NW, 1⁄4 NW, sec. 13, T. 16 N., R. 23 W.). Occurrences 

of limestone and limey sandstone were observed 140–180 ft above the base of the “middle 

Bloyd sandstone” in the Murray quadrangle to the southwest (Hudson and Turner, 2016).

The Atoka Formation (a) is composed of alternating beds of marine sandstone and 

shale that, in the southern Ozarks region, is interpreted as fluvio-deltaic deposits (Zachry 

and Sutherland, 1984). In this area, sandstone intervals of the Atoka Formation are 

principally very fine to fine grained and laterally extensive. The basal contact is well 

exposed approximately 30 miles (mi) west of the map area in Washington County where 

the Kessler Limestone Member at the top of the Bloyd Formation is unconformably 

overlain by shale of the Trace Creek Member of the Atoka Formation (Zachry and 

Sutherland, 1984). The contact between the Bloyd and Atoka Formations in the Buffalo 

River area is problematic due to the absence of the distinctive limestone lithology of the 

Kessler Limestone Member. The basal Atoka contact within the quadrangle is inferred 

from its stratigraphic position in the adjacent Boxley and Ponca 7.5' quadrangles. Within 

the Ponca quadrangle, Hudson and Murray (2003) placed the contact above a thin coal 

bed approximately 250 ft above the base of the “middle Bloyd sandstone.” In the Boxley 

quadrangle to the south, Hudson and Turner (2007) placed the Bloyd-Atoka contact at a 

similar level within a shale interval beneath an approximately 100-ft-thick interval of 

sandstone that holds up a prominent topographic ledge. This sandstone sequence is 

typical of Atoka facies in the region as it contains thin- to medium-bedded, very fine to 

fine-grained sandstone with ripple laminations.

STRUCTURAL GEOLOGY

The dominant structural feature of the Osage SW quadrangle is the

N.70° E.- to N.80° E- trending Compton fault and associated parallel folds that extend

across the center of the quadrangle. Structure contours on top of the Boone Formation

and base of the “middle Bloyd sandstone” are more closely spaced and are subparallel to

the fault near the east-northeast trending zone (fig. 4). The Compton fault dips to the

south-southeast and has normal-sense offset. Cumulative displacement of strata is

greatest along the eastern map boundary where as much as 350 ft of displacement is

observed across the fault and the associated longitudinal hanging wall syncline adjacent

to the south side of the fault, the Grogans Hollow syncline (cross section B–Bʹ). Rocks on

the northern footwall of the fault dip gently to the north. The Compton fault continues

eastward into the Ponca quadrangle, although its surface trace is now mapped slightly

north of that shown by previous mapping (Hudson and Murray, 2003; Hudson and

Turner, 2014a) based on the change from north dips in the footwall to the steep south dip

of the proximal hanging wall. Where Grogans Hollow turns northwest, a northeasttrending down-to-northwest fault branches from the Compton fault into its footwall,

decreasing the throw across the Compton fault to the west. Along the south side of

Cockran Hollow, the “middle Bloyd sandstone” is not displaced by faulting but rather

dips steeply to the south as a monoclinal flexure. In contrast, a lower limestone bed in the

Cane Hill is steeply dipping and is displaced by faulting indicating that propagation of the

Compton fault was restricted to a structural level below the level of the Bloyd Formation

in this area. The Compton fault is interpreted to continue to the west where it is concealed

below younger terrace and active-channel alluvial deposits (Qty) along Dry Creek. The

Compton fault coincides with an east-west-oriented fault, or series of faults, shown by

Middendorf and others (1997) to extend an additional 18 mi west of the Osage SW

quadrangle boundary.

A parallel zone of down-to-north monoclinal folds and small-offset normal faults 

lies about 1.2 mi south of the Compton fault. The Logan Mountain fault is the longest 

fault along this structural zone and starts in the upper reaches of Dry Creek and extends 

to the west past the quadrangle boundary. Cumulative displacement across the Logan 

Mountain fault including dipping beds on either side of the fault is as much as 120 ft with 

displacement increasing to the west. Together, the Compton fault and the paired southern 

fault and fold zone form an incipient graben.

The trace of the west-northwest striking Pickle Hollow fault in the north-central part 

of the quadrangle is mostly covered by younger terrace and active-channel alluvial 

deposits (Qty) but it drops the top of the Boone Formation (Mb) about 100 ft to the south. 

Structural offset at the eastern and western extents of the fault is accommodated by 

down-to-south monoclinal flexure of strata above the fault that is likely buried at depth. 

Purdue and Miser (1916) identified the Pickle Hollow fault, but they show the fault to 

extend about 1 mi east of Kenner Creek where we interpret a monocline with no discreet 

fault offset. West of the trace of the Pickle Hollow fault, strata are dropped to the south 

by a monoclinal flexure as strata of the Bloyd Formation are not displaced by faulting. 

Northeast of Dinsmore, the Boone Formation and Batesville Sandstone drop as much as 

80 ft to the south across the monocline. 

Ordovician rocks are exposed in the southeast corner of the quadrangle, in the 

Buffalo River valley. These rocks rise about 200 ft to the northwest into Whitley Creek 

valley and about 100 ft in Lost Valley (Clark Creek) in the upthrown limb of a broad 

east-northeast-trending monocline that represents the southwest continuation of the Adds 

Creek monocline on the Ponca quadrangle (Hudson and Murray, 2003). This monocline 

is part of a zone of faulted, northeast-trending monoclines that extends both farther to the 

northeast within the Ponca quadrangle (Hudson and Murray, 2003) and to the southwest 

within the Boxley quadrangle (Hudson and Turner, 2007) that together compose the 

southwestern part of the Ponca lineament (McFarland, 1988).

Structural data gathered from faults and deformation bands observed within the 

quadrangle, most too small to show on the map, give insight into causative stresses 

responsible for fault deformation. Sites where faults were observed are mostly restricted 

to the east-northeast-trending structural zone of the Compton fault or opposing paired 

fault and fold zones (fig. 4). These faults predominantly strike east-northeast and have 

normal-slip sense (figs. 4 and 5A). Paleostress inversions for a subset of faults with 

known slip direction and sense, using the method of Angelier (1990), suggest that most 

faults formed in tension with a least principal stress axis oriented south and shallow (fig. 

5B). Joints measured within the map area (1,038 total) are near vertical and distributed in 

several sets (fig. 5C). The dominant sets strike northeast, north-northwest, and northwest. 

CORRELATION OF MAP UNITS 

Qty

Qc QUATERNARY

Qto

a

bu

bl

hg

hc

Unconformity 

Atokan 

Unconformity

PENNSYLVANIAN

Morrowan 

Unconformity 

Unconformity

Mp 

Mf Chesterian 

MeramecianOsagean

Mbv

Unconformity MISSISSIPPIAN

Mb

Mbs

Unconformity

Of Upper Ordovician 

Unconformity

Oeu Middle Ordovician

Upper Mississippian 

Middle Mississippian

ORDOVICIAN 

Unconformity 

Ou Lower Ordovician

Lower Mississippian

Middle Pennsylvanain

Lower Pennsylvanian

OsageanKinderhookian

1150

1700

6

MAP EXPLANATION

Contact—Solid where location is accurate; long dash where location is 

approximate, short dash where inferred. In cross sections only, short dash 

where location projected above current surface

Normal fault—Ball and bar on downthrown block. Solid line where location 

accurate; long dash where location approximate, and dotted where 

concealed. In cross sections only, short dash where projected above 

current surface

Folds—Dashed where location is approximate

Syncline

Monocline—Arrow shows direction of dip

Structure contour line of equal elevation—Base of “middle Bloyd 

sandstone” that marks the base of the upper part of the Pennsylvanian 

Bloyd Formation (bu). Hachures point to closed areas of lower values. 

Contour interval 50 ft

Structure contour line of equal elevation—Top of the Mississippian Boone 

Formation (Mb). Hachures point to closed areas of lower values. Contour 

interval 50 ft

Buffalo National River boundary

PLANAR AND POINT FEATURES

Control point— Showing elevation (in feet) of the base of “middle Bloyd 

sandstone” of the upper part of the Pennsylvanian Bloyd Formation (bu)

Control point—Showing elevation (in feet) of the top of the Mississippian 

Boone Formation (Mb)

Strike and dip of bedding

Inclined bedding—Showing strike and dip

Horizontal bedding

Shoreline of Buffalo River

1460

1930

bu

bl

bl

bu

bu

bl

bu

bu

a

bu

bu

bu

hc

bl

bu

hc

hc

bl

hc

bl

hc

hc

Mf

hg

hc

hc

Of

Of

Oeu

Mb

Mb

Mb

Mbv

Mbs

Of

Of

Mbs

Mbs

Mf

Mf

Mf

Oeu

Oeu

hc

hc

hc

hc

a

a

a

hg

bu

hc

bl

hg

Qc

Qc

Qc

Qc

Qty

Qty

Qty

Qty

hg

hg

hg

hg

hg

Mb

Mbv

Mbv

Mf

Mf

Mf

Mf

Mf

Mf

Mp

Mp

Mp

Mp

Mb

bl

bl

bl

Mb

Mp

Mp

Mb

Mf

Mf

Mb

Mbv

Mf

Mf

Mf

Mf

Mf

Mf

Mf

Qty

Qty

Qty

Qc Qty

Qto

Mf Mf

Mf

Mbv

Mbv

Mbv

Mbv

U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Map 3416

SCALE 1: 24 000

1 1/ 2 0 1 MILE

1000 1000 0 2000 3000 4000 5000 6000 7000 FEET

1 0 .5 1 KILOMETER

ARKANSAS

MAP LOCATION

Base from U.S. Geological Survey 1:24,000-scale Osage SW, Ark., 1968

Universal Transverse Mercator projection, North American Datum 1927 (NAD 27)

10,000-foot grid based on Arkansas coordinate system, north zone

1,000-meter Universal Transverse Mercator grid ticks, zone 15

APPROXIMATE MEAN

DECLINATION, 2018 TRUE NORTH MAGNETIC NORTH

1°

CONTOUR INTERVAL IS 20 FEET

DATUM IS MEAN SEA LEVEL

Geologic mapping by K. Turner and M. Hudson 2014 through 2018

GIS database and digital cartography by K. Turner

T. Brandt scanned and registered the topographic base map

Publishing support provided by the Science Publishing Network, 

Denver Publishing Service Center

Edit and digital layout by L. Binder

Manuscript approved for publication August 27, 2018

A B

B'

A'

PICKLE

HOLLOW FAULT

COMPTON

COMPTON

FAULT

FAULT

LOGAN

FAULT

MOUNTAIN

NATIONAL RIVER BOUNDARY

Geologic Map of the Osage SW 7.5' Quadrangle, Newton, Madison, and Carroll Counties, Arkansas

By

Kenzie J. Turner and Mark R. Hudson

2018

Conversion Factors

Multiply By To obtain

meter (m) 3.281 foot (ft) 

kilometer (km) 0.6214 mile (mi)

Elevation, as used in this report, refers to distance above sea level.

mile (mi) 1.609 kilometer (km)

GROGANS

HOLLOW

SYNCLINE

CREEK

ADDS

MONOCLINE

Prepared in cooperation with the

National Park Service

For more information concerning this publication, contact:

Center Director, USGS Geosciences and Environmental Change Science Center

Box 25046, Mail Stop 980

(303) 236-5344

Or visit the Geosciences and Environmental Change Science Center Web site at

https://www.usgs.gov/centers/gecsc

To learn about the USGS and its information products visit

http://www.usgs.gov/ 

1-888-ASK-USGS

Any use of trade, product, or firm names in this publication is for descriptive 

purposes only and does not imply endorsement by the U.S. Government

This map or plate is offered as an online-only, digital publication. Users 

should be aware that, because of differences in rendering processes and 

pixel resolution, some slight distortion of scale may occur when viewing it on 

a computer screen or when printing it on an electronic plotter, even when it 

is viewed or printed at its intended publication scale

ScienceBase data release GIS and other files that support this report are 

available at https://doi.org/10.5066/P98DH5SP 

Suggested citation: Turner, K.J., and Hudson, M.R., 2018, Geologic map 

of the Osage SW 7.5' quadrangle, Newton, Madison, and Carroll 

Counties, Arkansas: U.S. Geological Survey Scientific Investigations Map 

3416, scale 1:24,000, https://doi.org/10.3133/sim3416.

ISSN 2329-132X (online)

https://doi.org/10.3133/sim3416