345 million to 310 million years BP : Mississippian


Mississippian Fossil Pictures





Spirifer Brachiopod

Rugose Coral



       The Mississippian Period began around 345 million years ago. The Kaskaskian Sea in

this area was then shallow and detrital, and still building the Chattanooga shale formation.

Not counting the Chattanooga shale, which is primarily a Devonian deposition, the

Mississippian formations in this area are about 350-400 feet thick, begin from 0 to about

200 feet below the surface, and possess a regional dip of around 15-20 feet per mile toward

the northwest. All Mississippian formations have been dated or placed using conodonts,

among other means. The Mississippian Period is represented in this area by the Chattanooga

Formation, the lower Mississippian Kinderhook and Osagean Series, the middle Mississippian

Meramecian Series, and the late Mississippian Chesterian Series of formations.

Mississippian formations here relate to the Early Carboniferous Tournaisian-Visean

formations of Europe. This area was probably just south of the equator and experiencing

an arid to warm temperate climate.

       The Kinderhook Series begins the all Mississippian formations in this area, and they

most commonly rest on either the Ordovician Cotter or the Devonian-Mississippian

Chattanooga formations. The earliest is the Bushberg Formation - a yellow sandstone, left

over parts of southwest Missouri. A bit later, the Bachelor Formation was formed which is

about 6 ft. thick in parts of southwest Missouri and northeast Oklahoma. It is a gray-green

calcareous sandstone with a 1-3 inch thick gray shale section. Much more commonly, the

base of the Mississippian Period formations appear as the Chouteau Group of the Kinderhook

Series and begin with the Compton Formation. Formed in a deeper sea, it is a 6-12 foot thick

green-gray layer of limestone appearing in northwest Arkansas, northeast Oklahoma, and

southwest Missouri. It thickens toward the east near Springfield, Mo., and is entirely absent

in some places as near Joplin, Mo. It is usually thinly bedded with the beds separated by

thin layers of green shale, but in spots it can be massively dolomitic or sparsely chertified.

It contains crinoids, blastoids, conodonts, foraminifers, and the bryozoan Evactiopora. It is

easily differentiated in McDonald Co., Missouri, roadcuts, lying on top of the Chattanooga


       On the far eastern edge of this section, the Sedalia Formation may overlie the Compton,

but the rest is overlain by the Northview Formation, including the Sedalia. The Northview

has been described as a blue-gray shaly-dolomitic siltstone. It is 2-5 ft. thick, sometimes

contains the Baird Mountain limestone member, can be found in roadcuts in McDonald County,

Mo., and contains worm borings and 'rooster tail' impressions made by Taonurus caudagalli.

Like the Compton, it also thickens toward the north and east near Springfield, Mo., and is

entirely absent in some parts of this area. It is the uppermost formation of the lower

Mississippian Kinderhook Series.

       The lower Mississippian Osagean Series appear next in time and are extremely important

in this area because between 1907 and 1958, over 9.5 million tons of zinc metal and over

2 million tons of lead metal recovered from about 550 million tons of mined material were

extracted from it in the Tri-State area. Part of a mineralized belt up to 30 miles wide and

nearly 100 miles long on the northwest flank of the Ozark uplift, the principal ore producing

areas were around Picher, Ok., Joplin-Webb City, Mo., and Granby, Mo. In Ottawa Co., Ok., at

least the main concentration of near-surface ore has been found in Townships 28 and 29 N.,

and Ranges 22, 23, and 24 E. The Diamond, Mo., area also had over 13 working mines with

one, the Smith Mine, 2 miles south and one-half mile west of Diamond, reporting rich ore

at 60 feet below the surface. The Granby, Mo., area was mined from 2'-275' deep, with most

ore found from 35'-100' deep. Besides the sphalerite and galena common to the rest of the

area, the Granby area also produced large amounts of the zinc silicate - calamine, the zinc

carbonate - smithsonite, and the lead carbonate - cerussite. Other concentrations pertaining

to certain strata will be discussed below.

       The Osagean Series with the middle Mississippian Meramecian Series have been

generally referred to as the Boone Chert. Their similar characteristics derive from having

underwent an incomprehensibly massive scale of torturing prior to the deposition of the

late Mississippian Chesterian Series. Possibly because of the imminent uprising of the

Ozark Dome, flexing and shearing occurred within hundreds of feet of earth creating

synclines and anticlines and cracks and fissures in the predominantly limestone beds. Pipe

slumps also occurred which downdropped 100' diameter pipes 25-40 feet, and whose tops

were filled with lower Chesterian deposits while the Chesterian surface was left relatively

level. Also, the flexing and shearing features of the Osagean series are not seen in the

Chesterian series aside from the Miami Shear Trough, another prominent feature of this

tortured landscape. It is a miles long, 300-500 foot wide, parcel of earth that has

downdropped 100-150 feet, and which happened apparently after the close of the Mississippi

Period because Pennsylvanian Cherokee shale has filled in above the downdropped Chesterian

deposits there.

        These motions created millions of cracks and voids, some of which were emptied

further by water or steam producing some voids hundreds of feet across, and all of which

needed to be filled by something. Apparently chert first filled most of the voids and the

ores came later because besides having ore zones filling flexes, shears, and cracks, they

also encircle and doughnut chert masses. This chertification appears to have been

accomplished before the late Mississippian Chesterian deposits were formed, and the ore

deposition occurred later, probably during the Pennsylvanian Period. Mineralized areas

exhibit a particular habit in that they exist as dolomite zones surrounded by jasperoid

zones, with a contact zone between the two. The dolomite zone is composed of massive and

crystalline dolomite (Ca, MgCO3), chert (SiO2), and some jasperoid (SiO2) and calcite (CaCO3).

The jasperoid zone consists of jasperoid, chert, and calcite. The contact zone is associated

with the major shearing and fracturing and contains the ore minerals, sphalerite (ZnS),

and/or galena (PbS). Some leaching of the minerals into the other two zones may exist,

sometimes making the dolomite zone worth mining. The outer edge of the jasperoid zone

leads to either a repeat in the sequence or to unaltered beds. Three major theories have

been called on to explain the occurrence of the mineral deposits, each of which leaves

questions unanswered. They are the meteoric-artesian hypothesis, the hydrothermal

hypothesis, and the magma gas hypothesis.

       The Osagean Series of formations begins with the Pierson Formation, typically lying

atop the Northview formation or the Chattanooga shale. For many years, this formation was

called the Fern Glen because of its similarity to the Fern Glen Formation of east-central and

southeastern Missouri. It is also similar to the St. Joe Formation of northern Arkansas which

has been described as basal Fern Glen. Lastly, it was considered the basal Boone layers. This

is a 35-60 ft. thick limestone containing frequent crinoids. It also contains much chert in

the Tri-State area, and zinc ore was mined from it at a depth of 155-165 feet southwest of

Joplin about two miles east of the state line. It is known to contain mineralized beds near

Picher, Ok., also, but being at a depth of near 500 feet, it was seldom, if ever, mined. In

Barry and McDonald counties, Mo., the Wolfpen Gap shale separates it from the overlying Reed's

Spring Formation.

       The Reed's Spring Formation is found in southwest Missouri, Arkansas, and Oklahoma.

In the 1930's, the mineralized horizon of the Picher, Ok., area was divided into beds which

were lettered A-R, excluding I, which resembles the number 1. This entire formation was

assigned the letter R. Thickness varies from 10 to over 150 feet, typically between 50 and

100 feet. It is a limestone formation, but in the TriState area, the chert content is very

high. Mineralization is most commonly found in the top 10-20 feet, if present. Its

surface was deeply eroded, with higher points reaching through Q to the top of P bed. The

uppermost portion of it is seen in the Shoal Creek valley and in a Joplin quarry, while it's

lower portions can be observed at the top of McDonald Co. roadcuts. Crinoids and the

bryozoan Evactiopora are common.

       Above the Reed's Spring lies the Elsey Formation. It is a 15-30 ft. thick limestone

layer similar to the Reed's Spring in that it is highly chertified in the Tri-State area. It

used to be considered as the lower part of the Keokuk formation, but is now seen as a

separate entity. It is represented as Q, P, and O beds in the older literature. O bed, the

uppermost, is noteworthy in possessing mineralization which spread blanket fashion over

a few to several hundred acres in various places. It is entirely exposed at the Kirshmann-

Jeffries quarry southwest of Joplin.

       The Grand Falls Formation is an 8-35 foot thick layer of tabular chert which replaced

the original upper Reed's Spring, Elsey, and lower Keokuk formations. It contains the

Orthotetes, Tetracamera, Delthyris, and Spiriferina fossil species. It is a localized

formation with its' type section at Grand Falls on Shoal Creek SW of Joplin, Mo.

       The Keokuk Formation finishes out this series. It includes the N-K beds. It ranges from

60-240 feet in thickness. The Southwest Lime Company has dug out over 30 acres of it from

a hill north of Neosho, Mo., and converted it into office and warehouse space. Keokuk

limestone has been used as road metal, building stone, and agstone.It can be seen

in its entirety at the Kirshmann-Jeffries quarry where it is about 100 ft. thick. It is also

exposed in southwest Barry Co. N bed, the lowest Keokuk, is 20-30 feet thick and provides

surface rock southwest of Joplin, including the Grand Falls chert in Shoal Creek at

McClelland Park.

       M bed is probably the richest ore producing bed, and is about 250-300 feet below the

surface near Picher, Ok. Near Joplin, ore was found 60-100 feet deep in the lower portion

of M bed. Strongly mineralized portions of it are often one-third the thickness of unaltered

portions. In some mines, the thick residual oil or tar of the Pennsylvanian shales has

migrated down into the M bed through shearing and drill holes. M bed solution thinning

appears to be responsible for depressions on the surface of the Pennsylvanian deposits

which led early miners to lodes of mineralization. M bed may correlate with the Burlington

Formation east of here. Its limestone is commonly crinoidal and fossiliferous. The Short

Creek Oolite Member lies at or near the top of M bed, and is typically 5-6 feet thick. The

uniformity in size and shape of the ooliths of this member separates it from other oolitic

limestone so it is commonly used as a marker. This is particularly useful as it marks the

top of the mineral rich M bed. It can contain crinoid pieces and brachiopods of the

Orthotetes and Rhipidomella species. It is an obvious rock type and can be seen in outcrops

in southwest Barry County and along I-44 from Joplin to Springfield, Mo.

       Depending upon erosion, the uppermost bed of the Keokuk Formation and consequently,

the Osagean Series, can be the M, the L, or the K bed. L bed can be anywhere from 0-30 feet

thick, and contains a white chert called by miners the 'butcher knife chert' or 'musical

flint' because of its glasslike conchoidal fracture and the tinkling sound produced when

walked upon. K bed can be from 0-40 feet thick, always shows an unconformity on top, and

is an important ore zone. Seneca Tripoli, a colloidal silicate found only within 8-10 miles

of Seneca, Mo., is mined from this bed. From this mine at least one fossil has been sent to

the Smithsonian Institution - a quadrangular cast of the extinct order Conularida. At the

time, this order was placed in with the Gastropoda, but more recently it has been more

strongly fixed with the Cnidaria. The author has also found one of these in a Newton

County streambed.

       The Warsaw Formation begins the middle Mississippian Meramecian Series in

this area. It can be seen in outcrops along I-44 above the Short Creek oolite. Its' thickness

increases to the north and east of us and produces the 'Carthage Marble' at Carthage, Mo.,

where its' thickness reaches 150 ft. About 10 feet of it is exposed at the bottom of the

cut on the southwest side of Oakleigh Mountain in Barry County, Mo. In northeast Oklahoma,

it is typically 110-130 feet thick, begins about 150 feet below the surface, and includes

beds J-B. It has produced Archimedes bryozoa and Spirifer brachiopods, and is quarried for

agstone and road metal.

       Erosion prior to the Warsaw deposition produced basins into the Keokuk as deep as the

Short Creek member which later filled with J bed deposits. In southeast Kansas, these

deposits are referred to as the Cowley Formation. J bed can be anywhere from 0-50 feet

thick, mostly dependent upon the unconformity on which it lays. It is most commonly only

3-5 feet thick, and can contain mineralized areas. H and G beds are similar in that both are

thinly bedded cherts and limestones, may be anywhere from 0-20 feet thick, usually are

2-5 feet thick, and together constitute an important ore horizon. F-B beds are spotty, though

some can reach a thickness of up to 32 feet, and are less commonly mineralized.

       The Meramecian Salem Formation may exist above the Warsaw in the far northeast part

of this section, as may the St. Louis Formation above that and which has produced echinoids,

melonechinus, Lithostrotionella coral colonies, and the Eublastoid species Cidaroblastus

parvus. Most of the Meramecian Series has been eroded from this area.

       The next period of sedimentation left us in this area is the Chesterian Series from

late Mississippian times. In northeast Oklahoma, this has been referred to as the Chester

Limestone, with the Hindsville Formation comprising the lower portions, and the Mayes

Formation comprising the upper. There, it is from 0-100 feet thick, about 100 feet below

the surface, and resting very irregularly on the upper Warsaw. The Chester is not chertified

and is much less deformed than the older rock, and at its base is found a conglomerate of

Boone chert and limestone pebbles.  Mineralization does occur in it, though not as frequently

as in the more tortured beds below. In the northern part of this area, the Carterville

formation has been used to describe the Chesterian remnants found in sinkholes and

depressions in the older rock. Some of these sinks have been reported as over 200 feet

thick. Corals, trilobites, and fish teeth have been found in Carterville deposits. It is a

highly heterogenous deposit composed of clay, conglomerate, oolitic limestone, shale,

and sandstone. The Carterville correlates to the Hindsville, Batesville, and Fayetteville

formations of the Chesterian Series where they are more fully developed as in Barry and

McDonald Co.'s of Missouri.

     The Hindsville Formation is the most common basal Chesterian deposit. It typically

lies upon Warsaw deposits and in northwest Arkansas, it is recognized as a basal member

of the Batesville Formation. It varies from 0-60 feet in thickness in this area, and all 60

feet of it is exposed on Oakleigh Mountain in Barry Co. It is usually a limestone with a thin

Boone chert conglomerate at its base, and may be capped with a gray siltstone. It contains

brachiopods, ammonoids, the conodont Spathognathodus, and frequently fish teeth in the

basal conglomerate.

       Above the Hindsville lies the Batesville Formation. It is found in southwest Missouri

and northwest Arkansas, and about 44 feet of it are exposed on Oakleigh Mountain. It is

normally a 35-50 ft. thick sandstone with discontinuous beds of limestone, and produces

brachiopods and pelecypods. Some buildings in Barry Co. are built of this sandstone.

       Finishing out the Mississippian Period remains is the Fayetteville Formation. This is

a black shale on limestone deposit up to 350 ft. thick in Arkansas, and 20-40 feet thick in

southwest Missouri. 23 feet of it is exposed on Oakleigh Mountain. It has given up some

brachiopods and ostracodes. Part of it is called the Wedington Sandstone Member from its

type section on Wedington Mountain in northern Washington Co., Arkansas. In Arkansas it is

50-150 ft. thick, and capping hills in southwest Missouri it is about 15 ft. thick.

Lepidodendron has been found in it. The Chesterian Series of Washington Co., Ark., has also

produced eublastoids of the Pentremites angustus, Pentremites rusticus, Pentremites

florealis, and Pentremites sulcatus species. Monosaccate, trilete spores have also been

found in Chesterian deposits.

       The Mississippian Period remnants in this area primarily represent fluctuations

of the Kaskaskian Sea. The Ozark Dome rose from late Mississippian to early Pennsylvanian

times and the Kaskaskian Sea retreated for good. The Appalachian mountains also began

to form during this period. Early in the Mississippian, vertebrates established themselves

on land and by the end, reptiles were evolving. Belemnites and nematodes appeared and

edrioasters became extinct.




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