112 GEROLOG Y. 
occupy an area of more than one hundred square miles, in the 
counties of Jasper and Newton. 
The Lncrinital Limestone is at once the most extensive and best 
characterized of the divisions of the Carboniferous limestone, It 
is made up of brown, buff, gray and white, coarse, crystalline, 
heavy bedded limestones. The darker colored, impure varieties 
prevail near the base, while the lighter, and more purely calcareous 
strata abound in the upper part. It everywhere contains globular, 
ovoid, and lenticular masses of chert, disseminated or arranged in 
beds parallel to the lines of stratification. These masses of chert 
are more abundant in the upper beds ; in fact, the upper beds are 
made up almost exclusively of this mineral. “ The strata of this 
formation are frequently intersected by joints resembling the sutures 
of the cranium. The remains of corals and mollusks are very 
abundant ; some of the strata are made up almost entirely of their 
exuvie, especially of the joints and plates of Cyinoideans. In 
the southwest, these strata rest upon some seventy or eighty feet of 
hard, porous and thick-bedded silicious rock, which are inclided 
in this formation, as they have more affinities with it than with the 
Chemung below. There are nine divisions of this formation in 
Missouri, which are quite well marked by their fossils and Jitho- 
logical characters. 
The Encrinital limestone extends from Marion County to Greene, 
forming an irregular zone on the east of the Archimedes beds. 
SYSTEM V—DEVONIAN. 
This system in Missouri contains: CHEMUNG Group, Ham- 
ILToN Group, ONANDAGA LIMESTONE, ORISKANY SANDSTONE. 
The Chemung group presents three formations, very distinct in 
lithological characters and fossil remains. They have received the 
following provisional names:—Chouteau Limestone, 85 feet ; Ver- 
micular Sandstone and Shales, 75 feet; Lithographic Limestone, 
125 feet. 
The Chouteau Limestone when fully developed is made up of tw 
very distinct divisions. : 
1st. At the top, immediately under the Encrinital limestone, 
we find some forty or fifty feet of brownish-gray, earthy, silico- 
magnesian limestone, in thick beds, which contain disseminated 
masses of white or limpid calcareous spar. This rock is very uni- 
form in character, and contains but few fossils. Reticulated corals, 
and Fucoidal markings, like the Cauda-ga//’, are most abundant. 
In the quarry it is quite soft, but becomes very hard on exposure, 
and forms a very firm and durable building rock. It is also 
hydraulic and forms a good cement. 
2d. The upper division passes down into a fine, compact, blue 
or drab, thin-bedded limestone, whose strata are quite irregular 
and broken. Its fracture is conchoidal, and its structure somewhat 
concretionary. Some of the beds are filled with a great profusion 
of most beautiful fossils. In many, the organic substance has been 
replaced by a calcareous spar. The most characteristic are 
Spirifer Marionensis, Productus Murchisonianus, Chonetes ornata, 
Atrypagregaria, A. Occidentalis, A. Obsceo-eoplicata, Leptaena 
depressa, Avicula Cooperensis, Mytilus elongatus, and several new 
species of Zrilobites. ; 
Chouteau Limestone has been applied to these rocks, as they were 
well developed at the Chouteau Springs in Cooper County, where I 
first found large quantities of its new, beautiful, and characteristic 
fossils. 
In the northeastern part of the State, the Chouteau limestone is 
represented by a few feet of coarse, earthy, crystalline, calcareous 
rock, like the lower division of the Encrinital limestone, as there 
developed. There is, indeed, in that part of the State, no change 
of lithological characters as you pass from the Encrinital limestone 
to this formation ; but the change in the organic remains is both 
sudden and great. 
The Vermicular Sandstone and Shales. ‘The upper part of this 
formation is usually a buff, or yellowish brown, fine-grained, pul- 
verulent, argillo-calcareous sandstone. It is usually perforated in 
all directions with pores, filled with the same materials more highly 
colored, and less indurated. This portion, when exposed to 
atmospheric agencies, often disintegrates, and leaves the rock full 
of winding passages, as if it were worm-eaten. 
This formation contains but few fossils, and those are in the 
upper portions. Spirifer Marionensis, Productus Murchisonianus, 
Chonetes ornata, Avicula circula, the Fucoids, above named, and 
the cauda-ga/ii, are most numerous. These beds can always be 
detected by the lithological characters.and its peculiar Fucotds. 
The Lithographic Limestone is a pure, fine, compact, even-tex- 
tured, silicious limestone, breaking rather easily, with a conchoidal 
fracture, into sharp, angular fragments. Its color varies from a 
light drab to the lighter shades of buff and blue. It gives a sharp, 
ringing sound under the hammer, from which it is called ‘‘ pot- 
metal,’’ in some parts of the State. It is regularly stratified in 
beds varying from two to sixteen inches in thickness, often present- 
ing, in mural bluffs, all the regularity of masonry, as at Louisiana, 
on the Mississippi. .The beds are intersected by numerous frac- 
tures, leaving surfaces covered with beautiful dendritic markings of 
oxide of iron. 
It has but few fossils. The most abundant are Spirifer Marion- 
ensis, S. cuspidatus, Productus Murchisonianus, P. minutus, Pro- 
teus Missourtensis, Filictes gracilis, a conularia, Fucoides cauda- 
galli, (?) and several large chambered cells. 
The Chemung rocks extend from Marion County to Greene, 
along the eastern border of the carboniferous strata. 
The Hamilton Group is made up of some forty feet of blue shales, 
and one hundred and seventy feet semi-crystalline limestone, con- 
taining Dalmania Calliteles, Phacops bufo, Spirifer mucronatus, S. 
sculptilis, S. congesta, Chonetes carinata, Favosites basaltica. 
Onondaga Limestone. This formation is usually a coarse gray or 
buff, crystalline, thick-bedded and cherty limestone, abounding in 
Terebratula reticularis, Orthis resupinata, Chonetes nana, Productus 
subaculeatus, Spirifer eurutetnes, Phacops bufo, Cyathophyllum rev- 
gosum, Emmorisia hemispherica, and a Pentamerus, like gateatus. 
No formation in Missouri presents such variable and widely dif- 
ferent lithological characters as the Onondaga. It is, generally, a 
coarse, gray, crystalline limestone; often, a somewhat compact, blu- 
ish concretionary limestone, containing cavities filled with green 
matter or calé-spar; in a few places, a white saccharoidal sand- 
stone ; in two or three localities, a soft, brown sandstone, and, at 
Louisiana, a pure white odlite. 
