GEOLOGICAL SURVEY CIRCULAR 160

DESCRIBED SECTIONS AND CORRELATION OF PALEOZOIC ROCKS AT GILBERT, CARVER, AND MARSHALL, ARKANSAS

By John C. Maher and Robert J. Lantz UNITED STATES DEPARTMENT OF THE INTERIOR Oscar L. Chapman, Secretary

GEOLOGICAL SURVEY W. E. Wrather, Director

GEOLOGICAL SURVEY CIRCULAR 160

DESCRIBED SECTIONS AND CORRELATION OF PALEOZOIC ROCKS AT GILBERT, CARVER, AND MARSHALL, ARKANSAS

By John C. Maher and Robert J. Lantz

Washington, D. C., 1952.

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

R.I9W. R.I8W. R.I7W. R.I6W. 5 Miles

Figure 1. --Location of Paleozoic sections and Marshall water well, Newton and Searcy Counties, Ark. DESCRIBED SECTIONS AND CORRELATION OF PALEOZOIC ROCKS AT GILBERT, CARVER, AND MARSHALL, ARKANSAS

CONTENTS Page Page1 ' Introduction ...... Representative measured sections of Representative measured sections Paleozoic rocks Continued of Paleozoic rocks ...... 3 Upper part of Boone formation, Everton formation, Gilbert ...... 3 Gilbert ...... St. Peter sandstone, Gilbert ...... 3 Lower part of Boone formation, Plattin limestone, Gilbert ...... 3 Gilbert ...... Fernvale limestone, Gilbert ...... 4 Batesville sandstone, Ruddell shale, Cason shale, Gilbert ...... 5 and Moorefield formation, Gilbert, Brassfield limestone, Gilbert ...... 5 Carboniferous (Mississippian) and Lafferty and St. Clair limestone, Ordovician rocks, Carver ... k ..., 10 Gilbert ...... 6 Log of Marshall water well 3, Marshall 12

ILLUSTRATION Page Figure 1. Location of Paleozoic sections and Marshall water well, Newton and Searcy Counties, Ark.

INTRODUCTION tions do not represent the maximum thickness of the beds within the area. Vertical intervals were meas­ In 1949 the U. S. Geological Survey, with the ured by hand level and tape, marked, and numbered cooperation of the Division of Geology, Arkansas on the outcrops. Correspondingly numbered channel Resources and Development Commission, began samples were then taken of the interval. The out­ stratigraphic investigations in northern Arkansas to crops were examined and described fully in the field aid in the search for oil and gas in the Arkansas with special emphasis on bedding and weathering. valley. Surface mapping of the Paleozoic rocks on The samples were then crushed, washed, and exam­ the north side of the Boston Mountains in Newton and ined in the office with the aid of a binocular micro­ Searcy Counties has been carried on concurrently scope. The sections included in this report combine with subsurface studies in the Arkansas valley since the microscopic and field descriptions. that time. The lower Paleozoic rocks have been In addition, the sample descriptions were mapped in detail, while the upper Paleozoic rocks plotted on a log strip on a scale of 1 in. equals 100 have received only incidental study. The first report ft. Colors were used to indicate the general lithol- resulting from these investigations was Bulletin 18 ' ogy; symbols to indicate details of the lithology; and of the Arkansas Division of Geology entitled, Geolog­ detailed descriptions of the samples were lettered ical formations penetrated by the Arkansas- along the side of the log opposite the position of the Louisiana Gas Co. no. 1 Barton well on the Cecil an­ corresponding sample. This permitted easy ticline, Franklin County, Ark.,by R. J. Lantz. A comparison with the sample log of the Marshall second report, a map of the Oil and Gas Investigations water well, which was drilled with cable tools. Series of the U. S. Geological Survey entitled, Geology of the Gilbert area, Searcy County, Ark., by J. C. The terminology used in the description of the Maher and R. J. Lantz, is now in press. This report samples is essentially that used by most midcon- presents a detailed surface map of lower Paleozoic tinent geologists making microscopic examinations rocks of a small area north of the Boston Mountains of well samples. The terms given below are used in where numerous small structural features are pres­ accordance with the Wentworth Grade Scale: ent. Detailed descriptions of measured sections and the well cuttings of the Marshall water well presented Silt, 0. 0038 mm to 0.062 mm in diameter. in this circular may be useful in establishing subsur­ Very fine grained sandstone, 0. 062 mm to face correlations in the Arkansas valley. 0.125 mm in diameter. Detailed descriptions of the surface sections in Fine-grained sandstone, 0.125 mm to 0. 25 this report are based on samples taken where each mm in diameter. formation is best exposed and, if possible, where Medium-grained sandstone, 0. 25 mm to each formation is best developed. Location of these 0. 50 mm in diameter. Coarse-grained sandstone, 0. 50 mm to 1.00 sections is shown on figure 1. In some places, satisfactory samples could not be obtained where the mm in diameter. formations are thickest, and, as a result, some sec­ Very coarse grained sandstone, 1.00 mm to 2. 00 mm in diameter. A limestone or dolomite which has rough tex­ Geological Survey, who has given generoasly of Ms ture is considered "crystalline" if crystal faces t ime and experience in checking correlations and may be seen; if crystal faces are absent, it is mapping. N. F. Williams, director, H. B. Foxhall, termed "granular. " A limestone or dolomite which former director, and C. A. Renfroe of the Division has smooth texture is called "dense. " of Geology, Arkansas Resources and Development Commission, extended many courtesies including the The bedding was described as follows: loan of the Marshall water-well samples and the use of a rock crusher Josiah Bridge, Mackenzie Gor­ Fissile, less than 1/16 in. thick. don, Jr., Helen Duncan, W. H. Hass, and Jean M. Platy, 1/16 in. to 1/2 in. thick. Berdan of the U. S. Geological Survey identified the Very thin bedded, 1/2 in. to 2 in. thick. fossils collected during the field work. Mackenzie Thin-bedded, 2 in. to 4 in. thick. Gordon, Jr., spent several days examining Missis- Medium-bedded, 4 in. to 12 in. thick. sippian rocks in the area and suggested the correla­ Thick-bedded, 12 in. to 36 in. thick. tions at Pate Mountain (section J in this report). Massive, more than 36 in. thick. Jackson King aided the writers in sampling the out­ crops. The National Research Council rock-color chart was not used in the descriptions. The classification and thickness of the Paleozoic The investigations in northern Arkansas have rocks at Gilbert, Carver, and Marshall are given in been aided immensely by H. D. Miser of the U. S. the table below.

Classification and thickness of Paleozoic rocks at Gilbert, Carver, and Marshall, Ark.

Thickness System Formation Gilbert Carver Marshall Ft in. Ft in. Ft Carboniferous Batesville sandstone 32 11 9 (Mississippian) Ruddell shale 17 7 9 Moorefield formation 1 2 9 Boone formation 355 ± 0 9 3TS Chert-bearing units 343 i 0 9 347 St. Joe limestone member 9 3 13 2 26 Basal sandstone member 2 6 1 7 2 Silurian Lafferty limestone 30 1 1 6 i 5 St. Clair limestone 34 5 Brassfield limestone 25 11 Ordovician Cason shale 13 0 14 Fern vale limestone 25 i 6 11 12 Plattin limestone 75 4 32 7 66 44 * St. Peter sandstone 32 4 75 7 Everton formation - 595(?) Powell(?) limestone - 215(?) Cotter(?) dolomite - 350(?) Jefferson City(?) dolomite - 350(?) Roubidoux(?) formation - -- 266(?) Gasconade(?) dolomite --- 9 REPRESENTATIVE MEASURED SECTIONS B. St. Peter sandstone OF PALEOZOIC ROCKS [Section measured on north bank of Brush Creek near south end of railroad bridge across Buffalo A. Everton formation River near center Si sec. 28, T. 16 N., R. 16 W., [ Section measured at small dome on Bear Creek near Searcy County, Ark. J center sec. 5, T. 15 N., R. 16 W., Searcy County, Ark.] Plattin limestone.

Plattin limestone. St. Peter sandstone: Ft in. Everton formation: Sandstone, very thin to thin- -Et bedded, gray to buff, dolomitic, Dolomite, massive, buff to gray- with medium-sized rounded and buff, finely granular, with pin­ frosted grains, and some point porosity; contains scattered scattered very coarse rounded rounded and frosted medium- sized and frosted grains ...... 1 0 sand grains ...... 5 6 Covered interval ...... 4 9 Covered interval ...... 4 10 Sandstone, thick-bedded, gray, Dolomite, massive, buff to dark dolomitic, fine- to medium- gray-buff, finely granular, with a grained; dark-gray, finely granu­ few pockets of medium- crystalline lar dolomite containing scattered calcite and scattered rounded and fine rounded and frosted sand frosted medium- sized sand grains; and a few coarsely cry­ grains ...... 4 9 stalline calcite veins ...... 1 11 Dolomite, massive, buff to dark Sandstone, thick-bedded, dark- gray-buff, finely granular to buff, dolomitic, with fine- to finely crystalline, with little medium-sized rounded and intercrystal porosity; contains frosted grains, grading down­ scattered rounded and frosted ward into white (weathering medium- sized sand grains...... 9 10 brown) sandstone with medium- Covered interval ...... 10 8 sized rounded and frosted Dolomite, massive, buff, finely grains ...... 2 3 granular; contains scattered Covered interval ...... 3 1 rounded and frosted medium- Sandstone, medium-bedded, white sized sand grains ...... 4 3 (weathering brown), with fine- Covered interval ...... 5 8 to medium-sized grains; most Dolomite, thick-bedded, buff to grains show crystal faces of gray-buff, finely granular, with secondary quartz ...... 13 10 veins of very coarsely crystal­ Sandstone, thin- to medium- line calcite; contains scattered bedded, white (weathering rounded and frosted medium- brown), with medium-sized sized sand grains ...... 3 2 grains and some scattered very Dolomite, massive, dark gray-buff, coarse grains; most grains show very finely granular, which con­ crystal faces of secondary tains scattered rounded and quartz ...... 5___6 frosted medium- sized sand grains; and buff sandy dolomite Everton formation. in which the sand grains are medium to coarse, rounded, and frosted ...... 5 6 C. Plattin limestone Dolomite, massive, buff, sandy, [ Section measured along railroad cut along north in which the sand grains are bank of the Buffalo River in SEiSWi sec. 29, T. medium to coarSe, rounded, and 16 N., R. 16 W., Searcy County, Ark. ] frosted; and dark gray-buff finely granular dolomite, which con­ Fern vale limestone. tains veins of very coarsely cry­ stalline calcite and scattered Plattin limestone: medium- sized rounded and froste'd sand grains...... 5 3" Limestone, massive, light-buff, very finely crystalline to dense; overed. contains a few scattered small caleite crystals ...... 5 i Plattin limestone --Continued Plattin limestone Continued Ft in. Ft in. Siltstone, deeply weathered, Limestone, platy to thin-bedded, massive, brown, limy, and very gray to gray-buff, very finely fine grained sandstone. Some crystalline to dense; contains khaki-colored, silty limestone at scattered small calcite and top ...... 5 1 pyrite crystals ...... 3 3 Limestone, thin- to medium-bedded, Limestone, thin- to medium-bedded, pink-mottled light-buff, very finely gray to gray-buff, figured, finely crystalline to dense; contains sty- granular to dense; appears as lolites and scattered small calcite rounded fragments of dense lime­ crystals ...... 3 6 stone in dense limestone matrix .. 2 1 Limestone, thin-bedded, gray to Limestone, very thin bedded to gray-buff, dense; contains scat­ thin-bedded, light-gray to light tered small calcite crystals ...... 4 9 gray-buff, dense; contains Limestone, thin- to medium-bedded, scattered small calcite and py­ light gray-buff, dense; contains rite crystals ...... 2 6 a few scattered small calcite Shale, platy, yellowish-gray to crystals ...... 4 0 tan, limy, and shaly limestone ... 8 Limestone, thick-bedded, gray to Limestone, very thin to medium- light gray-buff, dense; contains bedded, light-gray to gray-buff, very few scattered small calcite dense; contains scattered small crystals ...... 2 3 calcite crystals ...... 5 6 Limestone, massive, light-buff, Limestone, thick-bedded, light gray- dense; contains a few scattered buff, dense; contains scattered small calcite crystals and very small calcite and pyrite crystals .. 1 5 small calcite veins ...... 5 4 Limestone, rubbly, gray, figured, Limestone, medium-bedded, gray- dense; appears to be composed buff, dense; contains a few of rounded pebbles and angular scattered small calcite crystals blocks of gray, dense limestone and pyrite crystals ...... 1 0 in gray dense limestone, matrix ... 1 6 Shale, fissile, gray to gray-green, Limestone, thick-bedded, light and platy gray dense limestone, gray-buff, dense; contains in alternating beds; limestone scattered small calcite crystals .. 1 4 contains a few scattered small Limestone, very thin bedded to calcite crystals ...... 1 3 thin-bedded, light gray-buff, Limestone, thick-bedded, light dense; contains scattered small gray-buff, dense; contains calcite crystals ...... 2 1 scattered small calcite crystals, Limestone, medium-bedded, gray, stylolites, and pyrite ...... 1 2 very finely crystalline to dense; Limestone, thick-bedded, light contains scattered medium-sized gray-buff to light-buff, dense; rounded and frosted sand grains .. 7 contains a few scattered small Dolomite, medium-bedded, gray- calcite crystals ...... 2 7 buff, finely granular...... 1 1 Shale, platy, gray, limy ...... 3 Dolomite, medium-bedded, gray- Limestone, thick-bedded, light-buff, green, finely granular; contains dense; contains a few scattered scattered fine- to medium-sized small calcite crystals ...... 1 7 rounded and frosted sand grains; Limestone, very thin bedded, light- a few coarse rounded and frosted buff, dense; contains a few scat­ sand grains at the base ...... 10 tered small calcite crystals ...... 6 75 Shale, platy, gray-green, limy ..... 2 St. Peter sandstone. Limestone, massive, light gray- buff, dense; contains scattered small calcite crystals ...... 3 6 D. Fernvale limestone Limestone, platy to thin-bedded, [ Section measured along railroad cut along north buff, very finely crystalline to bank of the Buffalo River in SEiSWi sec. 29, T. dense; contains scattered small 16 N., R. 16 W., Searcy County, Ark. ] calcite and pyrite crystals ...... 4 6 Limestone, massive, buff, very Cason shale. finely crystalline to dense; con­ tains a few scattered small calcite Fernvale limestone: and pyrite crystals ...... 4 0 Limestone, platy to medium-bedded, Limestone, thick-bedded, light- buff to gray, dense; contains gray, very coarsely crystalline; scattered small calcite and pyrite contains limonite and pyrite blebs crystals ...... 1 10 and scattered pale-pink calcite fragments ...... 1 I Fernvale limestone --Continued F. Brassfield limestone Ft in. [Section measured on north bank of Bear Creek Limestone, massive, pinkish- about 1 mile from mouth. NW|SEi sec. 32, T. 16 buff to cream-colored, very N., R. 16 W., Searcy County, Ark. Fossil de­ coarsely crystalline; contains terminations by Jean M. BerdanJ pale-pink calcite fragments .... Limestone, massive, weathering St. Clair limestone. rubbly, pinkish-buff, very coarsely crystalline ...... Brassfield limestone: Limestone, thick-bedded, weath­ Ft in. ering rubbly, pinkish-buff to Calcite, orange and white, very light-gray, very coarsely cry­ coarsely crystalline, and stalline; contains a few limonite crinoid fragments poorly and pyrite blebs ...... 3 0 cemented by red to red-buff Limestone, thick-bedded, weather­ very finely crystalline lime­ ing rubbly, pink, coarsely cry­ stone; contains limonite and stalline to very coarsely pyrite blebs, irregular veins crystalline; contains limonite and vugs lined with white to clear and pyrite blebs, and many pale- coarsely crystalline calcite, and pink calcite fragments ...... 3 10 some very thin irregular Limestone, massive, pinkish- stringers of red very finely cry­ gray, coarsely crystalline to stalline limestone. Rhinopora very coarsely crystalline;" verrucosa Hall, Triplecia cf. contains many pale-pink calcite T. ortoni (Meek), Plectod'onta? fragments ...... _5__6_ sp., large strophomenoid im- 25 1 pression, brachiopod fragments, Plattin limestone. simulated cephalopod, lichad trilobite pygidium, trilobite fragments, Bythocypris sp., E. Cason shale thlipsurid ostracode, and Tubuli- [ Section measured near railroad crossing in bairdia? sp...... 7 10 sec. 31, T. 16 N., R. 16 W., Searcy County, Ark. Calcite, orange-red, orange, and Fossil determinations by Josiah Bridge] white, very coarsely crystalline, and crinoid fragments poorly Basal sandstone member of Boone formation. cemented by red very finely crystalline to dense limestone; Cason shale: contains limonite and pyrite Ft in. blebs, irregular veins and Clay shale, platy, green to khaki- vugs lined with white to clear colored ...... 2 0 coarsely crystalline calcite, Shale, platy, khaki-colored, and some irregular stringers slightly limy; contains scattered and pockets of red very finely large phosphate nodules as much crystalline to dense limestone. as 2 in. in diameter. Unidenti­ Unidentifiable cup coral, fiable fragments of large sponge, Rhinopora verrucosa Hall, Raphistoma sp., Cyclonema Dolerorthis cf. D. interstriata daytonensis Foerste?, CycTo- (Foerste), Leptaena rhomboidalis ceras? sp., and some nodular (Wilekens), Platystrophia sp., material that may be fragments Rhipidomella cf. R. hybrida of algae...... 7 6 (Sowerby), small orthoid, frag- Clay shale, platy, black and tan ment of punctate orthoid, other mottled to green ...... 2 3 brachiopod fragments, uniden­ Shale, platy, khaki-colored; con­ tifiable cephalopod fragment, tains abundant phosphate Encrinurus ? pygidium, Illaenus nodules ...... 1 3 pygidium, fragments of a large 13 0 illaenid trilobite, other trilobite Fernvale limestone. fragments, and Bythocypris sp. . 10 0 Brassfield limestone --Continued St. Clair limestone: Ft in. Ft Calcite, orange-red, orange, Covered interval I/ ...... and white, very coarsely cry­ Calcite, pink, orange, and stalline, and crinoid frag­ white, coarsely crystalline, ments poorly cemented by red and crinoid fragments ce­ very finely crystalline to mented by tan-buff to orange- dense limestone; contains buff very finely crystalline glauconite, limonite, and py- limestone; contains irregular rite blebs, irregular veins veins and vugs lined with and vugs lined with white to white coarsely crystalline clear coarsely crystalline calcite. Some thin irregular calcite, and some thin layers show a predominance irregular stringers of red of the very finely crystalline very finely crystalline to cementing material...... 24 dense limestone. Unidenti­ 34 fiable horn coral, Rhinopora Brassfield limestone. verrucosa Hall, Leptaena rhomboidalis (Wllckens), and illaenid trilobite frag­ H. Upper part of Boone formation ments ...... [Section measured along U. S. Highway 65 at Silver Covered interval ...... Hill, SWi sec. 7 and NWi sec. 18, T. 15 N., R. 25 11 16 W., and SE| sec. 12, T. 15 N., R. 17 W., Cason shale. . Searcy County, Ark. Fossil determinations by Mackenzie Gordon, Jr. Corals and bryozoans by NOTE. --Bedding of Brassfield limestone masked by Helen Dune an] secondary deposition on face of bluff--the whole interval appears as one massive bed. Batesville sandstone and Ruddell shale, uHdiiie*ea- tiated. G. Lafferty and St. Clair limestones Boone formation: [ Section measured on north bank of the Buffalo River in approximate center Ei sec. 36, T. 16 N., R. 17 Covered interval ...... 21 11 W., Searcy County, Ark. ] Chert, thin- to medium-bedded, white to light-gray (weatherlag Basal sandstone member of Boone formation. red), porous, spicular, finely figured; very small drusy Lafferty limestone: quartz crystals lining some cavities ...... 11 5 Limestone, medium- to thick- Chert, thin- to medium-bedded, bedded, gray, pyritic and white (weathering tan to red), limonitic, very finely cry­ porous, spicular, finely stalline to dense, with figured, tripolitic ...... IS 1 scattered orange medium- Covered interval ...... 36 2 sized calcite crystals ...... 6 2 Limestone, medium- to thick- Limestone, thick-bedded, gray, bedded, cream-colored pyritic and limonitic, very (weathering gray), coarsely finely crystalline to dense, to very coarsely crystalline, which contains scattered orange crinoidal; contains irregular medium-sized calcite crystals; lenses and layers of white and a few vugs lined with white (weathering tan) siliceous lime­ coarsely crystalline calcite ...... 6 1 stone or limy chert. The Limestone, massive, orange- coarsely crystalline limestone mottled gray to gray-buff, weathers to a very rough surface, pyritic and limonitic, very which shows cross-bedding ...... 24 3^ finely crystalline to dense, with Covered interval...... 8 4| scattered orange medium-sized Limestone, thick-bedded, light- calcite crystals ...... 5 5 gray, coarsely crystalline, Limestone, massive, orange- erinoidal; weathers to rough mottled gray-buff, pyritic, surface, which shows cross- medium-crystalline to dense ..... 5 0 bedding ...... 8 11 Limestone, massive, gray-buff to orange-buff, pyritic, very finely crystalline to dense, with pinkish-orange coarse calcite crystals and crinoid fragments.... 7 5 1 A11 bedding below this covered interval IB masked by secondary de­ 30 1 position on face of bluff. Boone formation --Continued Boone formation Continued Ft in. Ft in. Limestone, massive, light-gray, Limestone, thick-bedded, light- slightly glauconitic, coarsely gray, glauconitic, coarsely crystalline, crinoidal; crystalline, crinoidal; weathers weathers to rough surface, to a rough surface, which shows which shows cross-bedding. cross-bedding ...... 6 5 Fenestella sp., Orthotetes sp., Limestone, thick-bedded, light- Rhipidpmella (Perditocardinia) gray, slightly glauconitic, sp'. A?, Spirifer cf. S. gri- coarsely to medium-crystallise, mesi Hall, and Spirifer cf. S. crinoidal; weathers to rough logani Hall...... S> 6 surface, which shows,cross- Limestone, massive, light-gray, bedding. Rhombopora sp., coarsely crystalline, crinoidal; RhipidomeTIa (Perditocardinia) weathers to rough surface, sp. A, Rhynchopora sp. A?, which shows cross-bedding; and Spirifer logani~Hall ...... 5 i contains irregular lenses of Covered interval ...... 5 6 white (weathering tan) siliceous Limestone, siliceous, massive limestone or limy chert, light gray-buff, slightly glaueo- averaging about 2 ft long and nitic, coarsely to medium- 4 in. thick ...... 11 0 crystalline, grading to limy chert.. 5 6 Limestone, massive, light-gray, Chert, massive, white (weathering slightly glauconitic, coarsely tan), glauconitic, spicular, crystalline, crinoidal; weathers limy ...... § 6 to rough surface, which shows Limestone, gray-buff (weathering cross-bedding; contains dark-gray), glauconitic, medium- irregular lenses of white crystalline in irregular lenses (weathering tan) siliceous and thin irregular beds, which limestone or limy chert ...... 5 6 are in buff-spotted white glau­ Limestone, massive, light-gray conitic spicular figured limy to buff, glauconitic, coarsely chert ...... 11 0 crystalline; weathers to rough Chert, thin- to medium-bedded, surface, which shows cross- buff-spotted white (weathering bedding;- contains thin irregular tan), slightly glauconitic, limy, lenses of white (weathering tan) with irregular lenses and siliceous limestone or limy bands of gray (weathering chert Fenestella sp., rhombo- dark-gray) glauconitic poroid bryozoan piatycrinitid medium-crystalline limestone .... 27 6 columnal, Productus sp., Limestone, very irregularly Rhipidomella (Perditocardinia) bedded and banded, gray-buff, sp. A., Rhynchopora sp. A?, glauconitic, medium-crystalline Dielasma sp., and Spirifer and buff-spotted white (weather­ togani Hall...... 11 0 ing tan) glauconitic limy chert. Limestone, massive, light-gray, Zaphrentoid coral, Fenestella coarsely crystalline, crinoidal, sp., Orthotetes sp., Chonetes with scattered pink calclte sp., Productus sp., Avonia crystals to buff medium- williamsiana Girty, Schizophoria crystalline limestone; weathers sp., Rhynchopora? sp., Spirifer to rough surface, which shows logani Hall?, Cranaena? sp., cross-bedding; contains Tylothyris? sp., Brachythyris irregular lenses of white suborbiciiTaris (Hall), arid (weathering tan) siliceous lime­ Griffithideiysp...... 10 0 stone or limy chert. Rhipi - Limestone, thin-bedded, buff, domella (Perditocardinia) sp. A, medium-crystalline ...... 1 0 RhyncEopora sp. A, Rhynchopora Covered interval ...... 9 2 sp. A?, and Spirifer logani Hall? . 5 6 Limestone, very irregularly Limestone, thick-bedded, light- bedded, buff to gray-buff, gray, glauconitic, coarsely medium-crystalline, dolomrtie; crystalline; weathers to rough contains irregular lenses of surface, which shows cross- buff-spotted white (weatheriag bedding Fistuliporoid bryo­ tan) spicular limy chert con­ zoan fragment, Rhipidomella taining rhomb molds ...... 2T 6 (Perditocardinia) sp. A?, and Chert, irregularly bedded, teuff- Spirifer logani Hall...... 3 1 spotted white (weathering tan), Limestone, thin-bedded, white limy; contains irregular lenses of (weathering tan), siliceous; gray-buff slightly glauconitic or limy chert ...... 1 6 medium-crystalline limestone. Fenestella sp., Productus (DictyocTostus) crawfordtevUlensis Weller ...... V...... 3 8 Boone formation --Continued Boone formation. --Continued Ft in. St. Joe limestone member --Continued Covered interval ...... ~1 ID" Ft Chert, irregularly bedded, buff- Limestone, thin- to spotted white, limy; contains medium-bedded, light- thin lenses of gray-buff medium- gray to orange-buff, crystalline to finely crystalline pyritic, finely crystal­ limestone ...... 11 0 line; contains red to Chert, irregularly bedded, white pink coarsely crystalline to light-gray, spicular, dense; fragments of crinoids ...... 5 contains irregular lenses of light gray-buff medium- crystalline to finely crystal­ Basal sandstone member: line limestone ...... 11 0 Chert, irregularly bedded, gray- Sandstone, thin-bedded, white, spicular, dense. brown, slightly limy, Productus (Dictyoclostus) medium- to coarse­ crawfordsvillensis Weller ? ... 5 6 grained, with Taonurus- like markings on top sur­ Total thickness exposed 316 10 face ...... W. H. Hass regards this I. Lower part of Boone formation part of the sandstone as [ Section measured near U. S. Highway 65 bridge Mississippian (Kinderhook) across Bear Creek in SWi sec. 17, T. 15 N., R. in age on basis of his 16 W., Searcy County, Ark. 1 conodont identifications. Sandstone, medium-bedded, Boone formation (approximately a continuation of brown, medium-grained .... Silver Hill section (H) as shown by tracing beds W. H. Hass regards this about i mile along U. S. Highway 65.): lower part of the sandstone as Late Devonian (pre- Chert-bearing units: Grassy Creek) in age on the basis of his conodont identi­ Chert, irregularly bedded, fications. white to pale-pink, spicular; few very thin irregular beds of cream-colored finely crystalline lime­ J. Batesville sandstone, Ruddell shale, stone ...... 11 0 and Moorefield formation Chert, thin- to medium- [Section measured at Pate Mountain, NWi sec. 23, bedded, white to pale- T. 15 N., R. 17 W., Searcy County, Ark. Fossil pink, spicular; very thin determinations by Mackenzie Gordon, Jr. ] beds of cream-colored finely crystalline lime­ Fayetteville shale. stone ...... 5 6 Chert, irregularly bedded, Batesville sandstone: white to pale-pink, spicular; contains irreg­ Limestone, thin-bedded, dark-gray, ular lenses of cream- very fine to fine, sandy; few colored finely crystal­ medium-sized oolites. Bryozoan line limestone ...... 5 6 indet., Fenestella sp., crinoid Limestone, irregularly columnals, Composita? sp. bedded, pinkish-gray to indet., and gastropod? indet. .... 1 7 buff, slabby to rubbly, Sandstone, thin-bedded, gray finely crystalline; contains (weathering grayish-tan), limy, some white to pale-pink very fine to fine-grained ...... 4 10 spicular chert ...... 4 0 Limestone, thin-bedded, dark-gray, 26 0 finely granular. Bryozoan? indet., Productus (Diaphragmus) St. Joe limestone member: cestriensis Worthen, Dielasma ilTmoisensis Weller?, brachio- Limestone, thin- to medium- pods indet.., and ostracodes ...... 8 bedded, orange-buff, Clay shale, platy, khaki-colored finely crystalline; con­ to tan, slightly limy ...... 1 9 tains red to pink coarsely Limestone, thick-bedded, gray crystalline fragments of (weathering grayish-tan), dense, crinoids ...... silty; breaks with conchoidal fracture ...... 2 0 Batesville sandstone --Continued Batesville sandstone Continued Ft in. Ft in. Clay shale, platy, khaki-colored; Sandstone, medium-bedded, gray very fine, sandy, with black (weathering brown), very limy, stain on bedding planes ...... 10 fine-grained ...... Limestone, medium-bedded, gray, dense, slightly silty; contains scattered fine calcite crystals; Ruddell shale: breaks with conchoidal frac­ Shale, platy to fissile, gray- ture ...... 7 black and tan, micaceous, Clay shale, platy and crumbly, slightly silty ...... 4 3 khaki-colored to tan; contains Shale, platy to fissile, gray- a few limy nodules ...... 2 11 black, micaceous Caneyella Limestone, thin-bedded, light nasuta Girty?, Goniatites pinkish-tan, dense, silty; ' kentuckiensis Miller and . weathers rubbly ...... 8 Gurley, and Girtyoceras sp...... 5 6 Sandstone, platy, gray, limy, Shale, platy, tan to interlami- very fine to fine-grained ...... 1 9 nated black and tan, limy, very Sandstone, platy, tan, shaly, fine, sandy. Chonetes cf. C. very fine grained ...... 1 0 tumescens Easton, Camarotoe- Sandstone, thick-bedded, light chia purduei Girty, and COm- grayish tan, very fine to fine­ ppsita~s ubquadrata (Hall) ? ...... 2 4 grained, limy ...... 2 0 Shale, platy, gray-black Shale, platy, tan, slightly limy, (weathering brown), slightly silty; thin layers of tan very fine micaceous, limy ...... 1 0 grained limy sandstone ...... 9 Sandstone, platy, tan grading Limestone, medium-bedded, dark- downward into gray, very fine gray, medium-crystalline, grained, limy and shaly...... 1 0 very fine, sandy, with medium- Limestone, medium-bedded, gray, sized oolites, some of which finely crystalline, very fine, are elongate ...... 1 0 sandy. Mackenzie Gordon, Jr., Siltstone, medium-bedded, tan regards this bed as Ruddell in to brown, limy, and very fine age on basis of the following grained sandstone ...... 7 fossil identifications by him: Shale, platy, tan, slightly limy, Fenestella sp., Lingula sp. silty; thin layers of tan very indet., Orbiculoidea marshal - fine grained limy sandstone. lensis (Girty), Chonetes cf. C. Crinoid columnals, Agassizo- tumescens Easton, Productus crinus plates, Orthotetes sub- sp. indet;, Camarotoechia globosus Girty,~Leiorjijfnchus purduei Girty, LeiorhyncFus carboniTerum Girty and brachio- carboni'ferum Girty, Leiorhynchus pods indet...... 1 0 carboniferum polypleurum Girty, Sandstone, medium-bedded, gray Eumetria vera (Hall), Comppsita (weathering tan), very fine to cf. C. acinus Girty, Conularia fine-grained, very limy ...... 1 2 sp. indet., and ostracodes ...... 6 Shale, platy, tan, micaceous, Shale, platy, tan, very fine, sandy silty, and thin-bedded, tan and limy; limy nodules ...... 3 0 very fine grained shaly sand­ stone in alternating beds ...... 4 4 17 Limestone, medium-bedded, gray, Moorefield formation: medium-crystalline, with a few medium-sized oolites; very Limestone, very thin bedded, dark- fine, sandy at base. Crinoid gray, finely granular to finely columnals, Agassizocrinus crystalline, silty. Mackenzie plates, ? Productus (£)ia~ Gordon, Jr., reports that this phragmusfcestriensis Worthen, bed apparently represents the Productus (Echinoconchus) Moorefield formation as re­ cf. E. genevievensis Weller, stricted by him in A. A. P. G. Dielasma sp., brachiopods Bull., vol. 28, no. 11, pp. indet., and small gastropods 1626-1634, 1944. He identified indet...... i.. 1 6 the following fossils: Leio­ Shale, platy, tan, micaceous, rhynchus carboniferum Girty, slightly limy, silty. Aviculopecten Aviculopecten cf. A.~Fatesvil- sp. and Laevidentalium venustum lensis (Girty), Sphenotus, Meek and Worthen r ...... 1 0 and ostracodes ...... K. Carboniferous (Mississippian) Carboniferous (Mississippian) rocks --Continued and Ordovician rocks Boone formation --Continued [Section measured at Carver near the north end of St. Joe limestone member --Continued the Buffalo River bridge on State Route 123, Ft in. sec. 6, T. 15 N., R. 19 W., Newton County, Limestone, thin- and Ark. 1 irregular-bedded, reddish-buff, finely Carboniferous (Mississippian) rocks: to coarsely crystalline; Ft in. contains abundant Boone formation (lower part only; small crinoids and estimated 150 to 200 ft present white calcite crystals . 4 2 in cliff): Limestone, thin- and irregular-bedded, Chert-bearing units (from buff, finely crystal­ top of St. Joe limestone to line; contains abundant top of measured section): red calcite crystals Chert, irregular, thin and a few very thin to medium thick, gray, seams of greenish- finely pyritic, dense, buff shale ...... 3 9 in layers separated Shale, platy, green, by very thin bedded sandy; contains buff finely crystalline black phosphate pel­ limestone...... lets and red calcite Shale, platy, greenish- crystals ...... ______1_ buff, limy; contains 13 2 small pebbles of gray dense chert ...... Chert, thin-bedded, Basal sandstone member of light-gray to buff, Boone formation: finely figured, dense; contains buff finely Sandstone, thin-bedded, crystalline lime­ white, limy, com­ stone pebbles ...... 1 0 posed of medium- Shale, platy, very limy, sized round to sub- greenish-buff; con­ round slightly tains ostracodes...... frosted quartz grains. Chert, thin-bedded, Black phosphate gray-buff, finely pellets are scattered figured, dense, and throughout the sand­ buff finely crystalline stone ...... limestone...... W. H. Hass regards Chert, thin beds of this bed and overlying dark-gray to black, bed as Mississippian dense; maroon- (Kinderhook) in age tinged brown dense on basis of his cono- chert; and buff finely dont identifications. crystalline lime­ Specimens from stone ...... underlying beds were Limestone, very thin inconclusive. bedded, buff, finely Shale, fissile, grayish- crystalline to dense; green ...... contains some small Sandstone, greenish- white calcite cry­ white, composed of stals ...... white medium-sized 9 6 subround quartz grains and green limy St. Joe limestone member of the silt; abundant black Boone formation: phosphate nodules .... Limestone, thin- bedded, reddish- buff, finely crystalline; contains Ordovician rocks: abundant fossil fragments and cal­ Fernvale limestone: cite crystals ...... Limestone, thin-bedded, Limestone, thin- and pinkish-buff, crinoidal, irregular-bedded, gray, coarsely crystalline; medium to coarsely thin bed of buff-brown crystalline; contains very finely crystalline pyrite cubes ...... 1 10 limestone at base .... 10 Ordovician rocks--Continued Ordovician rocks--Continued Fernvale limestone--Continued St. Peter sandstone:

Ft in. Ft in. Limestone, thin- and Sandstone, soft, greenish- irregular-bedded, gray, white, very limy; com­ pyritic, crinoidal, posed of subround to coarsely crystalline; round frosted fine- to weathers rubbly...... 2 10 medium-sized quartz Limestone, thin- to grains...... 2 6 medium-bedded, gray- Covered interval...... 3 3 buff, crinoidal, coarsely Sandstone, thin-bedded, crystalline; crinoids white, limy; similar in are barrel-shaped...... _ composition to that above ..... 4 ~ rr Covered interval...... 2 4 Sandstone, thin-bedded, Plattin limestone: greenish-gray, slightly argillaceous, limy; similar Dolomite, medium-bedded, in composition to that above ... 5 yellowish-buff, slightly Dolomite, dull-gray, very black-mottled, finely finely granular, silty; con­ granular...... 2 10 tains very thin laminae of Dolomite, thin- to medium- very fine grained sand­ bedded, dark-gray to stone ...... 4 3 yellowish-buff, finely Sandstone, greenish-white, granular...... 2 4 limy; similar in com­ Dolomite, thin-bedded, buff position to the sandstones to gray, finely granular, above...... 4 6 and dolomitic limestone..... 1 10 Dolomite, gray-buff, very Dolomite, thin- and irregular- finely granular...... 7 bedded, gray-buff, finely Covered interval...... 2 7 granular, with a resinous Sandstone, white, limy, fine- luster; gray-buff finely to medium-grained ...... 4 crystalline to dense Sandstone, thin-bedded, brown, limestone; very thin seam dolomitic, fine-grained...... 4 9 of tan very fine grained Covered interval ...... 3 0 sandstone, in lower part.... 2 11 Sandstone, thin-bedded, white Covered interval...... 1 1 to brown, dolomitic, fine­ Limestone, thin- to thick- grained ...... 2 5 bedded, gray-buff, Dolomite, very thin bedded, slightly pink-mottled, gray-buff, fine-grained; dense; contains gray-buff contains abundant round dense chert...... 4 1 frosted fine sand grains ...... 4 Limestone, thin- to medium- Sandstone, medium-bedded, bedded, gray-buff, dense; buff-brown, dolomitic, contains scattered small fine-grained, and white calcite crystals...... 3 10 fine- to medium-grained Limestone, thin- to medium- sandstone...... 2 6 bedded, gray-buff, dense; Covered interval ...... 8 1 contains scattered small Sandstone, soft, very thin calcite crystals...... 3 10 bedded, pinkish- to greenish- Limestone, thin-bedded, white, fine- to medium- tan to gray, shaly...... 11 grained; grains exhibit Limestone, thin-bedded, secondary enlargement...... 2 5 gray-buff, dense; contains Covered interval ...... 4 9 scattered small calcite Sandstone, medium-bedded, crystals...... 2 7 white, limy, medium- Limestone, very thin bedded, grained; grains exhibit gray-buff, dense ...... 4 secondary enlargement ...... 5 6 Limestone, thin-bedded, (Note: 1 beds below this sandstone gray-buff, dense; contains are doubtfully included in pink to orange spots and the St. Peter sandstone scattered calcite crystals .... 2 9 pending completion of de­ Limestone, very thin bedded, tailed mapping) gray-buff, dense, with Dolomite, massive, dark- fine calcite veinlets ...... 1 7 gray to brown, medium- Limestone, thin-bedded, crystalline to coarsely light-gray, sandy, dense, crystalline...... 8 7 grading upward into nonsandy limestone ...... 1 8 This note was omitted from the first printing. 11 Ordovician rocks --Continued Ordovician rocks --Continued St. Peter sandstone --Continued Everton formation --Continued Ft in. Ft in. Sandstone, thin-bedded, Limestone, thin-bedded, white, fine- to medium- light-buff, finely figured, grained; grains are finely crystalline ...... 1 10 rounded and frosted ..... Covered interval...... 7 Covered interval...... Limestone, thin-bedded, Sandstone, medium-bedded, light-buff, finely figured, white, with fine- to finely crystalline ...... 2 medium-sized rounded Sandstone, white, slightly and frosted grains ...... limy, medium-grained; Covered interval...... grains exhibit secondary 75 enlargement...... Sandstone, massive, white, Everton formation: medium-grained; composed of rounded and frosted Limestone, medium-bedded, grains ...... 2 light-buff, slightly sandy, Limestone, gray-buff, finely crystalline ...... 1 3 microfossiliferous, finely Limestone, medium-bedded, crystalline; abundant buff, finely crystalline ...... 11 ostracodes ...... Limestone, medium-bedded, Sandstone, thin- to medium- buff, sandy...... 8 bedded, tan to white, fine- Limestone, light-buff, oolitic, to medium-grained; below or microfossiliferous, water level usually ...... 3 finely crystalline; grades 31 downward into buff sandy limestone ...... 1 1 LOG OF MARSHALL WATER WELL 3, Sandstone, medium-bedded, MARSHALL, ARK. white, very limy; composed of medium-sized rounded [Sample log, SW^SEi sec. 25, T. 15 N., R. 16 W., and frosted grains ...... 2 3 Searcy County, Ark. Altitude of well about 1, 000 Limestone, medium- to ft. Cable tool samples] thick-bedded, buff, medium- crystalline; contains scat­ Carboniferous (Mississippian) rocks: tered round sand grains Depth grading downward into (feet) white limy fine-grained Batesville sandstone and Ruddell shale sandstone ...... 1 11 shale, undifferentiated; no samples, Limestone, medium-bedded, but black shale cavings are present buff, finely crystalline in first sample and above forma­ to dense ...... 5 tions crop out nearby ...... 0-23 Sandstone, greenish-white, limy, fine-grained ...... 2 Boone formation: Dolomite, thin-bedded, brown, Limestone, gray- mottled medium-crystalline ...... 9 buff, slightly glauconitic, Covered interval ...... 2 9 medium-crystalline; Limestone, medium-bedded, buff dense chert ...... 23-27 buff, microfossiliferous, Dolomite, pinkish-buff finely crystalline; abundant to buff, finely crystalline ... 27-30 ostracodes ...... 1 11 Dolomite, pinkish-buff Limestone, medium-bedded, to buff, finely crystalline ; light-buff, sandy, finely buff spicular chert ...... 30-35 crystalline ...... 1 9 Dolomite, cream-colored, Limestone, thin-bedded, finely crystalline; tan- light-buff, sandy, finely mottled white dense crystalline ...... 1 3 chert ...... 35-40 Limestone, thin-bedded, Limestone, white, finely light-buff, oolitic or micro­ crystalline; brachiopods .... 40-45 fossiliferous, dense; Limestone, white, finely calcite; round frosted sand crystalline ...... 45- 50 grains in upper part...... 1 4 Dolomite, gray-white, finely Limestone, thin-bedded, granular; some thin beds light-buff, oolitic or of buff finely crystalline microfossiliferous, sandy; dolomite ...... 50-51 round frosted sand grains Limestone, buff, finely increase upward ...... 1 0 crystalline ...... 51-53 Like overlying bed, but very Dolomite, white, finely gran­ thin bedded ...... 1 2 ular; small crinoids...... 53-60 12 Carboniferous (Mississippian) rocks --Continued Carboniferous (Mississippian) rocks --Continued Boone formation --Continued _ ., Boone formation --Continued (feet) Depth Dolomite, white, finely v ' (feet) granular ...... 60- 70 Limestone, bone-white, Limestone, light-buff, siliceous; some white crinoidal, finely to dense chert; pyrite ...... 265-275 medium-crystalline ...... 70-75 Limestone, bone-white, Limestone, light-buff, siliceous; white spicular crinoidal, finely to chert ...... 275-290 medium-crystalline; Limestone, bone-white, trace of glauconite ...... 75-85 siliceous; white spicular Limestone, light-buff, chert; slightly gray-white crinoidal, finely to dense chert ...... 290-300 medium-crystalline ...... 85-120 Limestone, bone-white, Dolomite, white, finely siliceous; white dense, granular, limy ...... 120-130 chert ...... 300-310 Limestone, light-buff, finely Limestone, cream-colored, crystalline; trace of white finely crystalline; white milky chert ...... 130-133 dense chert ...... 310-326 Limestone, white, very Dolomite, white, finely crinoidal, finely crystal­ granular; white dense line ...... 133-140 chert ...... 326-335 Limestone, white, very Dolomite, cream-colored, crinoidal, finely crystal­ finely granular; gray- line; brachiopods ...... 140-145 white dense chert ...... 335-350 Limestone, cream-colored, Limestone, brown, finely crinoidal...... 145-150 granular to finely crystal­ Limestone, buff, finely to line; gray-white to smoky medium-crystalline; dense chert with black dull-white semi-granular inclusions ...... 350-365 finely spicular chert ...... 150-155 Limestone, cream-colored, Limestone, buff, finely finely granular to finely crystalline ...... 155-160 crystalline; some cream- Dolomite, cream-colored, colored dense chert ...... 365-370^ limy; dull-white semi- granular chert ...... 160-165 St. Joe limestone member: Dolomite, cream-colored, finely granular; white Limestone, white, dense chert ...... 165-170 chalky; little white Dolomite, cream-colored, dense chert ...... 370-375 finely granular ...... 170-175 Limestone, white, Dolomite, cream-colored, chalky; trace of very very finely glauconitic, fine glauconite ...... 375-380 finely granular to finely Limestone, white, crystalline; pyrite; chalky, with few fine spines ...... 175-180 round sand grains .... 380-384 Dolomite, cream-colored, Limestone, brown, very finely glauconitic, pyritic, finely cry­ finely granular to finely stalline, with thin crystalline; spines ...... 180-185 layers of dark-green Dolomite, white, finely finely glauconitic granular; white dense shale ...... 384-390 chert; spines...... 185-190 Limestone, gray-buff, Dolomite, white, finely pyritic, with abundant granular; white semi- pink calcite crystals granular chert ...... 190-200 and crinoids ...... 390-396 Dolomite, bone-white, Basal sandstone member: Gray very siliceous finely subangular to subround glauconitic, finely pyritic sandstone ...... 396-398 granular to finely cry­ stalline ...... 200-204 Silurian rocks: Dolomite, bone-white, very siliceous, finely granular Lafferty and St. Clair limestones, to finely crystalline ...... 204-240 undifferentiated: Limestone, bone-white, siliceous; white dense Limestone, brown, finely chert ...... 240-250 crystalline; brown dense Limestone, bone-white, chert; brachiopods ...... 398-400 siliceous ...... 250-265 13 Silurian rocks Continued Ordovician rocks --Continued Lafferty and St. Glair limestones, St. Peter sandstone --Continued undifferentiated --Continued Depth Depth (feet) (feet) Sandstone, white, limy, Limestone, brown, finely pyritic, fine- to medium- crystalline ...... 400-410 grained; grains are sub- Limestone, brown, finely round and frosted ...... 550-590 crystalline, with pink calcite crystals; pyrite ... 410-420 Everton formation: Limestone, buff, finely crystalline,- with pink Limestone, white, finely calcite crystals ...... 420-425 crystalline ...... 590-592 Limestone, cream-colored Dolomite, brown, sandy, to buff, finely crystalline, finely granular. Dolomite with pink calcite crystals; has white subround pyrite ...... 425-430 medium-sized sand grains Limestone, buff, crinoidal, scattered in it ...... 592-606 with pink calcite crystals; Sandstone, white, fine- to pyrite ...... 430-446 medium-grained, with Limestone, white, finely subround and frosted crystalline, with pink grains ...... 606-607 calcite crystals; oolitoid Dolomite, buff, medium- objects ...... 446-450 crystalline ...... 607-616 Limestone, white, finely Sandstone, white, fine­ crystalline ...... 450-454 grained ...... 616-617 Dolomite, brown, very finely Brassfield limestone member granular, in part sandy; absent. blue-green shale frag­ ments; brown coarsely cry­ Ordovician rocks: stalline dolomite ...... 617-620 Dolomite, brown, finely Cason shale: granular to finely crystal­ line ...... 620-628 Sandstone, gray-green, Dolomite, gray, slightly pyritic, glauconitic, slightly silty, very finely granular .. 628-630 limy, very fine .....*...... 454-455 Dolomite, buff to brown, Shale, black ...... 455-466 very sandy, medium- Shale, pale-green, pyritic, crystalline; contains with black phosphate white subround medium- pellets ...... 466-468 sized sand grains ...... 630-635 Dolomite, buff, very sandy Fernvale limestone: (40- 50 percent sand)...... 635-644 Dolomite, dark-brown, almost Limestone, white, coarsely resinous, finely granular; crystalline; tra'ce of pink trace of white mineral calcite ...... 468-480 dolomite ...... 644-650 Dolomite, brown, finely to Plattin limestone: medium -crystalline; white calcite crystals ...... 650-657 Limestone, buff, finely cry­ Dolomite, brown, finely stalline ...... 480-490 granular ...... 657-665 Dolomite, buff-brown, Dolomite, brown, medium- finely granular ...... 490-508 crystalline ...... 665-670 Dolomite, buff-brown, Dolomite, brown, fine, finely crystalline ...... 508-510 sandy...... 670-674 Limestone, brown, finely Sandstone, white, limy, crystalline to dense ...... 510-533 fine-grained ...... 674-676 Shale, gray, hard, limy ...... 533-535 Dolomite, brown, fine, Limestone, brown, finely sandy ...... 676-682 crystalline to dense ...... 535-546 Sandstone, white, fine- to medium-grained ...... 682-684 St. Peter sandstone: Dolomite, dark-brown, finely granular ...... 684-695 Sandstone, white, sobround, Sandstone, white, fine­ slightly frosted, slightly grained ...... 695-696 limy, fine-grained; Dolomite, drab, shaly, and pyrite ...... 546-550 dolomitic mudstone ...... 696-700

14 Ordovician rocks --Continued Ordovician rocks Continued Everton formation --Continued Everton formation Continued Depth Depth (feet) (feet) Dolomite, brown, sandy; Dolomite, brown, finely contains white subround granular, with pin­ medium-sized sand point porosity ...... 860-866 grains ...... 700-705 Dolomite, very dark Dolomite, dark-brown, brown, resinous, very finely crystalline ...... 705-712 finely granular ...... 866-870 Dolomite, brown, sandy 712-717 Dolomite, brown, sandy .... 870-875 Sandstone, white, medium- Dolomite, brown, resinous, grained ...... 717-718 very finely granular ...... 87S-880 Dolomite, brown, finely Dolomite, brown, very crystalline ...... 718-720 fine, sandy, very finely Dolomite, brown, shaly, or granular ...... 880-885 dolomitic mudstone ...... 720-732 Dolomite, brown, finely Sandstone, tan, dolomitic, crystalline ...... 885-890 fine-grained, and Dolomite, buff, medium- white fine-grained sand­ crystalline ...... §90-895 stone with white silica Dolomite, buff, medium- cement ...... 732-736 crystalline, with thin Dolomite, brown, silty ...... 736-740 layers of white fine­ Dolomite, buff-brown, very grained sandstone ...... 895-900 sandy...... 740-744 Sandstone, white, fine­ Sandstone, white, fine­ grained ...... 900-901 grained ...... 744-746 Dolomite, buff, sandy ...... 901-907 Dolomite, buff-brown, very Sandstone, white, fine­ sandy ...... 746-750 grained ...... 907-908 Dolomite, buff, finely gran­ Dolomite, buff to brown, ular ...... 750-758 finely to medium- Dolomite, buff, finely gran­ crystalline ...... 908-918 ular; some buff sandy Sandstone, white, fine­ dolomite ...... 758-760 grained ...... 918-920 Dolomite, buff, sandy, Dolomite, buff, finely finely granular ...... 760-764 crystalline ...... 920-927 Dolomite, buff, very finely Dolomite, buff, with medium- granular ...... 764-770 sized subround sand Dolomite, buff, very finely grains included ...... 927-930 granular, with some white Dolomite, buff, sandy ...... 930-945 calcite crystals ...... 770-776 Dolomite, buff, finely Dolomite, very dark brown, granular to finely cry­ finely granular ...... 776-786 stalline ...... 945-950 Dolomite, very dark brown, Dolomite, buff, finely cry­ finely granular; thin stalline ...... 950-960 layers of black dolomitic Dolomite, buff, sandy ..... 960-970 shale ...... 786-792 Dolomite, buff, medium- Dolomite, brown, finely crystalline, sandy ...... 970-977 granular; calcite...... 792-802 Dolomite, buff, fine, sandy . 977-980 Dolomite, buff, sandy ...... 802-806 Sandstone, white, fine­ Dolomite, dark brown, finely grained ...... 980-981 granular ...... 806-818 Dolomite, buff, very finely Dolomite, tan, very finely granular ...... 981-993 granular ...... 818-820 Sandstone, white, fine- Dolomite, tan to buff, sandy.. 820-824 to medium-grained ...... 993-995 Dolomite, brown, finely Sandstone, white, dolomitic, crystalline ...... 824-830 fine- to medium-grained . 995-1^001 Dolomite, buff, finely cry­ Limestone, buff, finely stalline ...... 830-837 crystalline ...... 1, 001-1, 016 Dolomite, brown, finely Limestone, white, sandy.. 1,016-1,020 granular ...... 837-842 Sandstone, white, slightly Sandstone, white fine- to limy, fine- to medium-grained, with sub- medium-grained ...... 1, 020-1, 026 round grains showing some Limestone, buff, finely secondary growth ...... 842-844 crystalline; contains Dolomite, brown, finely tan oolites ...... 1, 026-1, 030 crystalline ...... 844-850 Dolomite, buff, medium- Dolomite, brown, sandy 850-855 crystalline ...... 1,030-1,033 Dolomite, brown, finely Sandstone, white, fine- granular ...... 855-860 to medium-grained .... 1,033-1,036 15 Ordovician rocks --Continued Ordovician rocks --Continued Everton formation --Continued Everton formation Continued Depth Depth (feet) (feet) Dolomite, buff, finely Dolomite, cream- granular, slightly colored, very finely sandy...... I, 036-1,041 granular, with Sandstone, white, dolo- scattered fine sand mitic, fine- to grains ...... 1,165-1,185 medium-grained ...... 1, 041-1, 045 Dolomite, buff, medium- Powell(?) limestone: crystalline, with a thin seam of green Shale, gray-black...... 1, 185-1,187 shale ...... 1, 045-1,050 Dolomite, cream- Dolomite, buff, medium- colored, very finely crystalline to granular ...... 1,187-1,192 coarsely crystalline.... 1, 050-1, 055 Shale, gray-black ...... 1,192-1,194 Dolomite, buff, finely Dolomite, cream- granular ...... 1,055-1,060 colored, very finely Dolomite, buff, finely granular ...... 1,194-1,197 crystalline to finely Like overlying beds but granular ...... 1,060-1, 067 with gray-black shale Sandstone, white, fine- partings and green to medium-grained .... 1,067-1,076 shale partings ...... 1,197-1,199 Dolomite, buff-brown, Dolomite, cream- very sandy ...... 1, 076-1, 080 colored, very finely Dolomite, brown, very granular ...... 1,199-1,219 finely granular...... 1, 080-1, 085 Shale, green, waxy ...... 1,219-1,220 Dolomite, brown, very Dolomite, buff, finely finely granular, with granular; some black white siliceous shale seams ...... 1, 220-1, 224 oolites and sandstone Shale, black...... 1,224-1,226 grains cemented in Dolomite, gray, finely white silica ...... 1, 085-1, 090 granular; some included Sandstone, white, sili­ sand grains ...... 1, 226-1, 229 ceous ...... 1, 090-1, 094 Shale, black...... 1,229-1,230 Dolomite, buff, sandy.... 1,094-1,099 Dolomite, gray, finely Shale, dark-green ...... 1, 099-1,100 granular; some included Dolomite, buff-brown, sand grains ...... 1, 230-1, 243 very finely granular .... 1,100-1, 103 Shale, gray-black, slightly Shale, gray, dolomitic ... 1,103-1,104 dolomitic ...... 1,243-1,250 Dolomite, buff-brown, Dolomite, buff to brown, very finely granular; finely granular ...... 1, 250-1, 256 c ale it e crystals ...... 1,104-1,115 Shale, gray-black ...... 1, 256-1, 257 Dolomite, very dark Dolomite, buff, medium- brown to black, silty ... 1,115-1,120 crystalline; cream- Dolomite, buff to brown, colored very finely very finely granular .... 1,120-1,125 granular dolomite ...... 1, 257-1, 262 Dolomite, buff, very Shale, dark-brown to. finely granular ...... 1,125-1,130 black ...... 1,262-1,264 Dolomite, buff, medium- Dolomite, gray to buff, crystalline to coarsely finely granular ...... 1,264-1,275 crystalline, with included Shale, dark-brown to subround sand grains... 1,130-1,135 black ...... 1,275-1,277 Dolomite, buff, finely Dolomite, buff, very crystalline, with finely granular ...... 1, 277-1, 280 included sand grains.... 1, 135-1,140 Dolomite, buff, medium- Dolomite, buff, finely to coarsely crystalline . 1, 280-1,284 crystalline ...... 1, 140-1, 145 Dolomite, cream- Dolomite, buff, finely colored, granular ..... 1,284-1,296 crystalline; gray- Shale, dark-brown to white chert ...... 1,145-1,150 black ...... 1,296-1, 298 Dolomite, buff, medium- Dolomite, cream- crystalline, sandy ..... 1,150-1, 155 colored, granular...... 1,298-1,306 Dolomite, buff, finely Shale, dark-brown to crystalline; some black ...... 1,306-1, 308 sandy dolomite ...... 1, 155-1,163 Dolomite, cream- Dolomite, cream- colored, granular...... 1,308-1,313 colored, very finely Shale, dark-brown to granular ...... 1,163-1,165 black ...... 1,313-1, 315 16 Ordovician rocks --Continued Ordovician rocks Continued Powell(?) limestone --Continued Cotter (?) dolomite --Continued Depth Depth (feet) (feet) Dolomite, cream- Dolomite, gray-buff, colored, finely cry­ very finely granular; stalline ...... 1,315-1,320 white dense chert ...... 1,450-1,455 Dolomite, cream- Dolomite, buff, finely colored, finely crystalline ...... 1,455-1,460 granular ...... 1,320-1,325 Dolomite, buff, medium- Dolomite, cream- crystalline to coarsely colored, finely crystalline; dolomite granular; gray-buff rhombs in white silica., 1,460-1,465 dense chert ...... 1,325-1,330 Dolomite, buff, medium- Dolomite, buff, finely crystalline to coarsely crystalline ...... 1,330-1,335 crystalline; much Dolomite, buff, finely white silica with dolo­ crystalline; gray dense mite rhombs; green chert; white dense shale fragments; white chert ...... 1,335-1,340 to tan dense chert 1,465-1,470 Dolomite, gray-buff, Dolomite, buff, finely finely crystalline ..... 1,340-1,342 crystalline; dull-white Shale, blue-green...... 1,342-1,344 chert ...... 1,470-1,475 Dolomite, brown, Dolomite, brown, finely finely crystalline ..... 1,344-1,350 crystalline; white to Dolomite, buff, finely milky dense chert 1,475-1,480 crystalline; thin seams Dolomite, buff, finely of light-green shale ... 1,350-1,360 crystalline ...... 1,480-1,490 Dolomite, buff, finely Dolomite, cream- granular'...... 1,360-1,365 colored, finely granu­ Dolomite, buff, granular 1,365-1,370 lar ...... 1,490-1,495 Dolomite, buff, medium- Dolomite, buff, finely crystalline; pyrite .-. 4 . 1,370-1,374 crystalline ...... 1,495-1,510 Dolomite, buff, finely Dolomite, buff, finely to medium-crystalline; crystalline; gray chert , 1,510-1,518 tan and brown banded Dolomite, buff, finely dense chert ...... 1,374-1,380 crystalline; buff Dolomite, cream- __ coarsely crystalline colored, very finely dolomite; dolomite granular ...... 1,380-1,390 rhombs in white Dolomite, gray, silty ... 1,390-1,400 silica; banded white and gray chert; white Cotter(?) dolomite: finely oolitic chert 1,518-1,525 Dolomite, buff, finely Dolomite, dark-buff, crystalline ...... 1,525-1,530 finely crystalline ..... 1,400-1,405 Dolomite, buff, finely Dolomite, dark-buff, crystalline; trace of finely crystalline; white dense chert ...... 1,530-1,535 brown dolomite Dolomite, buff, finely rhombs in white sili­ crystalline; smoky- ca; much jvhite dense gray chert ...... 1,535-1,540 chert; gray and white Dolomite, cream- banded chert ...... 1,405-1,410 colored, medium- to Dolomite, buff, finely coarsely crystalline 1,540-1,544 crystalline; dolomite Dolomite, gray-buff, rhombs in- silica; finely crystalline 1,544-1,550 calcite crystals ...... 1,410-1,420 Dolomite, cream- Dolomite, buff, finely colored, finely to crystalline; tan-gray medium-crystalline 1,550-1,560 dense chert ...... 1,420-1,426 Dolomite, cream- Dolomite, gray-buff, colored, finely finely crystalline ..... 1,426-1,430 granular ...... 1,560-1,565 Dolomite, buff to brown, Dolomite, buff, finely finely crystalline to granular ...... 1,565-1,570 dense; white dense Dolomite, buff, finely chert...... 1,430-1,440 crystalline; white Dolomite, gray-buff, dense chert; black- very finely granular 1,440-1,450 speckled gray chert 1,570-1,575

17 Ordovician rocks --Continued Ordovician rocks --Continued Cotter (?) dolomite --Continued Cotter (?) dolomite --Continued Depth Depth (feet) (feet) Dolomite, buff, finely to Dolomite, cream- medium-crystalline; colored, very finely white dense chert ...... 1,575-1,580 granular ...... 1,685-1, 697 Dolomite, buff, medium- Dolomite, brown, finely crystalline to coarsely crystalline ...... 1, 697-1, 700 crystalline ...... 1,580-1,585 Dolomite, gray-buff, finely Dolomite, buff, finely granular ...... 1,700-1, 705 crystalline; white dense Dolomite, buff, coarsely chert with included crystalline ...... 1, 705-1, 710 dolomite rhombs...... 1,585-1,590 Dolomite, buff, finely Dolomite, buff, finely to medium-crystalline. . 1,710-1,720 crystalline; white dense Dolomite/ cream- chert; calcite crystals . 1,590-1,595 colored, finely granu­ Dolomite, buff, medium- lar; white dense chert; crystalline to coarsely pyrite ...... 1,720-1,730 crystalline; white dense Dolomite, cream- chert ...... 1,595-1,600 colored, finely granu­ Dolomite, buff, finely lar ...... 1,730-1,734 crystalline ...... 1,600-1,610 Dolomite, dark-buff, Dolomite, buff, very finely crystalline; finely granular ...... 1,610-1,615 white- and cream- Dolomite, cream- banded pyritic chert ... 1, 734-1, 740 colored, finely granular; Dolomite, buff, finely trace of white dense crystalline; pyrite ..... 1, 740-1, 744 chert ...... 1,615-1,620 Dolomite, buff, finely Dolomite, buff, finely crystalline; brown crystalline; white dense dense chert ...... 1, 744-1,750 chert; pyrite; milky chert ...... 1,620-1,627 Jefferson City(?) dolomite: Dolomite, buff, finely granular to finely cry­ Dolomite, gray-buff, stalline ...... 1,627-1,635 finely granular; brown Dolomite, buff, finely dense chert ...... 1, 750-1,756 granular to finely cry­ Dolomite, dark-buff, stalline; black-speckled, finely crystalline; light-gray dense chert.. 1,635-1,640 brown chert with Dolomite, cream- white spots ...... 1,756-1,760 colored, very finely Dolomite, buff, sandy, granular; trace of sandy finely granular ...... 1, 760-1, 770 chert ...... 1,640-1,645 Dolomite, brown, medium- Dolomite, cream- crystalline, with cal­ colored, very finely cite and dolomite granular ...... 1,645-1,650 rhombs in white Dolomite, brown, finely silica; trace of tan crystalline; much oolitic chert ...... 1, 770-1, 780 white porcelainlike Dolomite, buff, finely chert with brown dolo­ granular; white dense mite rhombs included; chert; tan translucent gray dense chert with chert containing white speckles...... 1,650-1,660 Archeosoyphia? ...... 1,780-1,785 Dolomite, buff, finely Dolomite, buff, finely crystalline, with few granular; white dense scattered subround chert with fine black sand grains ...... 1,660-1,670 specks ...... 1, 785-1, 790 Dolomite, buff, medium- Dolomite, cream- crystalline to coarsely colored, very finely crystalline; much granular ...... 1,790-1, 795 white porcelainlike Dolomite, cream- chert with included colored, medium- dolomite rhombs ...... 1,670-1,675 crystalline to Dolomite, buff, finely coarsely crystalline; crystalline, white white interstitial pyritic chert ...... 1,675-1,680 silica; white figured Dolomite, brown, finely chert ...... 1, 795-1, 800 crystalline; white dense chert ...... 1,680-1,685 18 Ordovician rocks Continued Ordovician rocks Continued Jefferson City(?) dolomite Continued Jefferson City(?) dolomite Continued Depth Depth (feet) (feet) Dolomite, buff, finely Dolomite, gray, very granular; white sub- finely granular ...... 1,920-1,925 translucent figured Dolomite, brown, finely chert; white subtrans- crystalline ...... 1, 925-1, 930 lucent oolitic chert..... 1, 800-1,805 Dolomite, buff, finely Dolomite, buff, finely granular ...... 1,930-1,945 granular; white dense Dolomite, gray, slightly chert ...... 1, 805-1, 810 silty ...... 1,945-1,950 Dolomite, buff, medium- Dolomite, cream- crystalline; dolomite colored, finely granu­ rhombs in white silica; lar; gray-white white dense chert ...... 1, 810-1, 815 slightly figured chert... 1, 950-1, 960 Dolomite, gray-buff, Dolomite, cream- finely to medium- colored, finely crystalline; glauconite . 1,815-1,820 granular, with in­ Dolomite, gray-buff, cluded sand grains ..... 1, 960-1, 965 finely crystalline; Dolomite, brown, finely white subtranslucent crystalline ...... 1, 965-1, 970 oolitic and sandy Dolomite,. brown, finely chert ...... 1,820-1,825 granular ...... 1,970-1,974 Dolomite, cream- Dolomite, cream- colored, medium- colored, sandy, very crystalline to coarsely finely granular; white crystalline; white very sandy chert ...... 1,974-1,980 subtranslucent oolitic Dolomite, cream- and sandy chert...... 1,825-1, 830 colored, very finely Dolomite, gray-buff, granular ...... 1,980-1,987 finely granular;-white Dolomite, gray-white, finely dense chert ...... 1, 830-1, 835 to medium-crystalline .. 1, 987-2,000 Dolomite, white, coarsely Dolomite, cream- crystalline ...... 1, 835-1, 840 colored, finely Dolomite, buff, finely granular ...... 2,000-2,005 crystalline ...... 1, 840-1, 845 Dolomite, gray-buff, Dolomite, buff, finely finely crystalline ...... 2,005-2,010 crystalline; white Dolomite, gray-buff, dense chert; white finely crystalline; white subtranslucent dense chert ...... 2,010-2,020 chert ...... 1,845-1,850 Dolomite, buff, coarsely Dolomite, dark-buff, crystalline, trace of tan finely crystalline ...... 1,850-1,860 translucent chert ...... 2,020-2,030 Dolomite, gray-white, Limestone, dark-buff, finely granular; slightly finely crystalline, sandy, in part ...... 1,860-1, 865 dolomitic ...... 2,030-2,033 Dolomite, dark-buff, Limestone, dark-buff .... 2,033-2,040 finely crystalline ...... 1, 865-1, 870 Limestone, light-buff, Dolomite, cream- finely crystalline; tan colored, finely subtranslucent chert; granular ...... 1,870-1,885 smoky chert...... 2, 040-2, 060 Dolomite, brown, finely Limestone, light-buff, crystalline ...... 1, 885-1, 890 finely crystalline ...... 2,060-2,075 Dolomite, brown, finely Limestone, cream- crystalline; brown colored, finely crystal­ dense chert containing line; white dense chert; scattered sand grains .. 1, 890-1, 895 tan slightly figured Dolomite, cream- subtranslucent chert ... 2,075-2,080 colored, very finely Limestone, cream- granular ...... 1,895-1,900 colored, finely cry­ Dolomite, dark-brown, stalline; chert not so resinous, finely abundant ...... 2,080-2,086 granular ...... 1,900-1,910 Dolomite, cream- Dolomite, gray-green, colored, finely with included sand granular ...... 2,086-2,090 grains ...... 1,910-1,915 Dolomite, cream- Dolomite, buff, granu­ colored, fine, sandy ... 2,090-2,096 lar ...... 1,915-1,920 19 Ordovician rocks Continued « Ordovician rocks --Continued Jefferson City(?) dolomite Continued Roubidoux(?) formation --Continued Depth Depth (feet) (feet) Limestone, buff, finely Dolomite, buff, coarsely crystalline to dense; crystalline; light-buff white subtranslucent oolitic chert...... 2, 230-2, 240 chert ...... 2,096-2,100 Limestone, buff, finely crystalline to dense ... 2, 240-2,255 .Roubidoux( ?) formation: Limestone, buff, finely crystalline to dense; Limestone, buff, finely gray-black dense crystalline, faintly chert ...... 2,255-2,260 oolitic ...... 2,100-2, 105 Limestone, buff, finely Limestone, buff, finely crystalline to dense .... 2, 260-2, 267 crystalline; gray sub- Dolomite, white, sandy, translucent chert ...... 2,105-2,110 or limestone ...... 2, 267-2, 270 Limestone, dark-buff, Limestone, buff, finely finely crystalline to crystalline to dense; dense ...... 2,110-2,130 light-buff sandy chert; Limestone, buff, sandy, gray translucent chert.. 2, 270-2, 275 with some white dolo- Limestone, buff, finely mitic and siliceous crystalline to dense; oolites ...... 2,130-2, 134 gray-black dense Sandstone, white, limy, chert ...... 2, 275-2, 290 fine-grained ...... 2,134-2,137 Limestone, cream- Dolomite, gray, sandy; colored, finely white subtranslucent crystalline to dense .... 2, 290-2, 300 sandy chert ...... 2, 137-2, 142 Limestone, cream- Limestone, cream- colored, finely colored, finely crystalline to dense; crystalline to dense .... 2,142-2,150 tan figured chert ...... 2, 300-2, 306 Limestone, cream- Dolomite, gray-buff, colored, finely coarsely crystalline; crystalline to dense; white dense chert; tan tan to smoky-gray subtranslucent chert.... 2, 306-2, 310 dense chert ...... 2,150-2,170 Dolomite, cream- Dolomite, gray-buff, colored, very finely finely granular; tan , granular; white to light- to smoky-gray dense buff subtranslucent chert ...... 2, 170-2, 172 chert ...... 2, 310-2, 320 Sandstone, gray, quart- Dolomite,, buff, finely zitic ...... 2,172-2, 178 granular; quartz cry­ Sandstone, white, dolo- stals ...... 2,320-2, 325 mitic, fine-grained .... 2, 178-2,180 Dolomite, gray-buff, Limestone, cream- finely granular to colored, finely finely crystalline; crystalline to dense; blue chert with gray tan to gray subtrans­ speckles ...... 2,325-2, 330 lucent chert ...... 2,180-2, 187 Dolomite, buff, finely Sandstone, white, dolo- crystalline to finely mitic, fine- to granular; white dense medium-grained ...... 2,187-2,190 chert containing dolo­ Sandstone, white, limy, mite rhombs ...... 2, 330-2, 336 fine- to medium-grained 2, 190-2,192 Dolomite, buff, sandy .... 2, 336-2, 340 Limestone, cream- Dolomite, cream- colored, fine, sandy ... 2,192-2,200 colored, finely cry­ Limestone, cream- stalline; white sandy colored, fine, sandy; chert ...... 2,340-2, 345 tan translucent chert ... 2, 200-2, 204 Dolomite, cream- Limestone, buff, finely colored, finely crystal­ crystalline to dense .... 2, 204-2, 210 line ...... 2,345-2,350 Dolomite, white, finely Dolomite, white, sandy, crystalline, with granular; trace of included round sand white and gray chert ... 2, 350-2, 355 grains ...... 2,210-2,215 Dolomite, white, sandy... 2, 355-2, 360 Dolomite, white, finely Sandstone, white, dolo- crystalline ...... 2, 215-2, 220 mitic, fine- to medium- Dolomite, buff, coarsely grained, with subround crystalline ...... 2, 220-2, 230 to subangular grains ... 2^360-2, 366 20 Ordovician rocks Continued Ordovician rocks Continued Depth Gasconade(?) dolomite --Continued (feet) Depth Gasconade(?) dolomite: (feet) Dolomite, cream- Dolomite, cream- colored, medium- colored, medium- crystalline; blue-gray crystalline ...... 2,366-2, 375 chert; translucent Dolomite, cream- sandy chert ...... 2,395-2,400 colored, finely granu­ Dolomite, cream- lar; dull-white pyritic colored, coarsely chert...... 2,375-2, 380 crystalline ...... 2, 400-2, 405 Dolomite, gray, finely Dolomite, cream- granular ...... 2,380-2, 385 colored, coarsely Dolomite, cream- crystalline; white colored, finely cry­ dolomite rhombs ...... 2, 405-2,410 stalline ...... 2, 385-2, 390 Dolomite, cream- Dolomite, cream- colored, coarsely colored, medium- crystalline ...... 2,410-2, 415 crystalline ...... 2,390-2, 395 Total depth 2,415

21 INT.-OOP. SEC., WASH.. D.C.19«J»