History of Tama County, Iowa, together with sketches of their towns, villages and townships, educational, civil, military and political history, portraits of prominent persons, and biographies of representative citizens, Part 9

Author: Union publishing company, Springfield, Ill., pub
Publication date: 1883
Publisher: Springfield, Ill., Union publishing company
Number of Pages: 1088

USA > Iowa > Tama County > History of Tama County, Iowa, together with sketches of their towns, villages and townships, educational, civil, military and political history, portraits of prominent persons, and biographies of representative citizens > Part 9

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The St. Peters sandstone formation is remarkably uniform in thickness through-

out its known geographical extent, and it occupies a large portion of the northern half of Allamakee county, immediately beneath the drift.

Trenton Group -With the exception of the Trenton limestone, all the limestones of both Upper and Lower Silurian age in Iowa are magnesian limestone - nearly pure dolomites. This formation occupies large portions of Winneshiek and Allama- kee counties and a small part of Clayton The greater part of it is useless for eco- nomic purposes; but there are some com- pact, even layers that furnish fine material for window-caps and sills. Fossils are so abundant in this formation that in some places the rock is made up of a mass of shells, corals and fragments of trilobites, cemented by calcareous material into a solid rock. Some of these fossils are new to science and peculiar to Iowa.

The Galena limestone is the upper form- ation of the Trenton Group. It is 150 miles long, and seldom exceeds 12 miles in width. It exhibits its greatest develop- ment in Dubuque county. It is nearly a pure dolomite, with a slight admixture of silicous matter; good blocks for dressing are sometimes found near the top of the bed, although it is usually unfit for such a purpose. This formation is the source of the lead ore of the Dubuque lead mines. The lead region proper is confined to an area of about 15 miles square in the vicinity of Dubuque. The ore occurs in vertical fissures, which traverse the rock at regular intervals from east to west; some is found in those which have a north and south direc- tion. This ore is mostly that known as Galena, or sulphuret of lead, very small -

IHISTORY OF IOWA.

quantities only of the carbonate being found with it.

Cincinnati Group .- The surface occu- pied by the Maquoketa shales is more than 100 miles iu length, but is singularly long and narrow, seldom reaching a mile or two in width. The most northern exposure yet recognized is in the western part of Winneshiek county, while the most south- erly is in Jackson county, in the bluffs of the Mississippi. The formation is largely composed of bluish and brownish shales, sometimes slightly arenaceous, sometimes calcareous, which weather into a tenacions clay npon the surface, and the soil derived from it is usually stiff and elayey. Several species of fossils which characterize the Cineinnati Group are found in the Maquo- keta shales, but they contain a larger num- ber than have been found anywhere else in these shales in Iowa, and their distinct faunal characteristics seem to warrant the separation of the Maquoketa shales as a distinct formation from others in the group.

UPPER SILURIAN SYSTEM.

Niagara Group .- The area occupied by the Niagara limestone is 40 and 50 miles in width, and nearly 160 miles long, from north to south. This formation is entirely a magnesian limestone, with a considerable portion of silicious matter, in some places, in the form of chert or coarse flint. A large part of it probably affords the best and greatest amount of quarry rock in the State. The quarries at Anamosa, LeClaire and Farley are all opened in this forma- tion.

DEVONIAN SYSTEM.

Hamilton Group .- The area of surface occupied by the Ilamilton limestone and

shales is as great as those by all the form- ations of both Upper and Lower Silurian age in the State. Its length is nearly 200 miles, and width from 40 to 50. A large part of the material of this is quite worth- less, yet other portions are valuable for economic purposes; and, having a large geographical extent in the State, is a very important formation. Its value for the production of hydraulic lime has been demonstrated at Waverly, Bremer county; the heavier piers and other material re- quiring strength and durability. All the Devonian strata of Iowa evidently belong to a single epoeh. The most conspicuous and characteristic fossils of this formation are brachiopodes, corals and mullusks. The coral Acervularia Davidsoni occurs near Iowa City, and is known as "Iowa City marble" and "Bird's Eye marble."

CARBONIFEROUS SYSTEM.

Of the three groups of formations that constitute the carboniferous, viz: the sub -. carboniferous, coal measures and Permian, only the first two are found in Iowa.

Subcarboniferous Group .- This group occupies a very large area of surface. Its eastern border passes from the northeast- ern part of Winnebago county, with con- siderable direetness in a southeasterly direction to the northern part of Washing- ton county. It then makes a broad and direct bend nearly eastward, striking the Mississippi at Muscatine. The southern and western boundaries are to a consider- able extent the same as that which separates it from the real field. From the southern part of Pocahontas county it passes soutlı- east to Fort Dodge, thence to Webster City, thence to a point 3 or 4 miles north-

HISTORY OF IOWA.

east of Eldora, in Hardin county, thence southward to the middle of the north line of Jasper county, thence southeastward to Sigourney, in Keokuk county, thence to the northeastern corner of Jefferson county, thence sweeping a few miles eastward to the southeast corner of Van Buren county. Its arc is about 250 miles long, and from 20 to 50 miles wide.

The Kinderhook Beds .- The most south- erly exposure of these beds is in Des- Moines county, near the mouth of Skunk river. The most northerly now known is in the eastern part of Pocahontas county, more than 200 miles distant. The princi- pal exposures of this formation are along the bluffs which border the Mississippi and Skunk rivers, where they form the eastern and northern boundary of DesMoines county; along English river, in Washing- ton county; along the Iowa river in Tama, Marshall, Hamlin and Franklin counties, and along the DesMoines river in Hum- boldt county. This formation has consid- erable economic value, particularly in the northern portion of the region it occupies. In Pocahontas and Humboldt counties it is invaluable, as no other stone except a few boulders are found here. At Iowa Falls the lower division is very good for building purposes. In Marshall county all the limestone to be obtained comes from this formation, and the quarries near Le Grand are very valuable. At this point some of the layers are finely veined with peroxide of iron, and are wrought into both useful and ornamental objects. In Tama county the oolitic member is well exposed, where it is manufactured into lime. Upon exposure to atmosphere and frost it crum-

bles to pieces; consequently it is not valu- able for building purposes.

The remains of fishes are the only fossils yet discovered in this formation that can be referred to the sub-kingdom Vertebrata; and so far as yet recognized, they all be- long to the order Se.achians Of Articu- ticulates, only two species have been recog- mized, both of which belong to the genus Phillipsia. The sub-kingdom Mollusca is also largely represented The Radiata are represented by a few crinoids, usually found in a very imperfect condition. The sub kingdom is also represented by corals. The prominent feature in the life of this epoch was molluscan. It overshadowed all other branches of the animal kingdom. The prevailing classes are: Lamellibranch- iates, in the more arenaceous portions; and Brachropods in the more calcareous por- tions. No remains of vegetation have been detected in any of the strata of this formation.

The Burlington limestone formation consists of two distinct calcareous divi- sions, separated by a series of siliceous beds; both divisions are crinoidal. The Burlington limestone is carried down by the southerly dip of the Iowa rocks, so that it is seen for the last time in the State in the valley of Skunk river, near the south- ern boundary of Des Moines county, which is the most northerly point that it has been found, but it probably exists as far north as Marshall county. Much valuable mate- rial is afforded by this formation for eco- nomic purposes. The upper division furnishes excellent common quarry rock. Geologists are attracted by the great abundance and variety of its fossils-cri- noids-now known to be more than 300.

HISTORY OF IOWA.

The only remains of vertebrates discov- ered in this formation are those of fishes, and consist of teeth and spines. Boncs of bony fish, on Buffington creek, Lonisa county, is an exposure so fully charged with these remains that it might with pro- priety be called bone breecia.

Remains of Articulates are rare in this formation; so far as yet discovered, they are confined to two species of trilobites of the genus Phillipsia. Fossil shells arc very common.

The two lowest classes of the sub-king- dom Radiata are represented in the genera Zaphrentis, Amplexus and Syringaposa, while the highest class, Echinoderms, are found in -most extraordinary profusion.

The Keokuk limestone formation is to be seen only in four counties-Lee, Van Buren, Henry and DesMoines. In some localities the upper siliceous portion is known as the Geode bed; it is not recog- mizable in the northern portion of the formation, nor in connection with it where it is exposed, about 80 miles below Keo- kuk. The geodes of the Geode bed are more or less masses of silex, usually hol- low and lined with crystals of quartz; the outer crust is rough and unsightly, but the crystals which stud the interior are often very beautiful; they vary in size from the size of a walnut to a foot in diameter.

This formation is of great economic value. Large quantities of its stone have been used in the finest structures in the State, among which are the postoffices at Dubuque and DesMoines. The principal quarries are along the banks of the Missis- sippi, from Keokuk to Nauvoo. The only vertebrate fossils in the formation are fishes, all belonging to the order Selachians,

some of which indicate that their owners reached a length of 25 or 30 feet. Of the Articulates, only two species of the genus Phillipsia have been found in this forma- tion. Of the Mollusks no Cephalopods have yet been recognized in this forma- tion in Iowa. Gasteropods are rare; Brachiopods and Polyzoans are quite abundant. Of Radiates, corals of genera Zaphrentis, Amplexus and Aulopora are found, but crinoids are most abundant. Of the low forms of animal life, the proto- zoans, a small fossil related to the sponges, is found in this formation in small num- bers.

The St. Louis limestone is the uppermost of the sub-carboniferous group in Iowa. It occupies a small superficial area, consisting of long, narrow strips, yet its extent is very great. It is first seen resting on the geode division of the Keokuk limestone, near Keokuk; proceeding northward, it forms a narrow border along the edge of the coal fields in Lee, DesMoines, Henry, Jefferson, Washington, Keokuk and Ma- haska counties; it is then lost sight of until it appears again in the banks of Boone river, where it again passes out of view under the Coal Measures, until it is next seen in the banks of the DesMoines, near Fort Dodge. As it exists in Iowa, it consists of three tolerably distinct sub- divisions-the magnesian, arenaceous and calcareous. The upper division furnishes excellent material for quicklime, and when quarries are well opened, as in the north- western part of VanBuren county, large blocks are obtained. The sandstone, or middle division, is of little economic value. The lower, or magnesian division, furnishes a valuable and durable stone, exposures of

HISTORY OF IOWA.

which are found on Lick creek, in Van Buren county, and on Long creek, seven miles west of Burlington.

Of the fossils of this formation, the vertebra es are represented only by the remains of fish, belonging to the two orders, Selachians and Ganoids. The Articulates are represented by one species of the trilobite, genus Phillipsia; and two ostracoid genera, Cythra and Beyricia. The Mollusks distinguished this formation inore thau any other branch of the animal kingdom. Radiates are exceedingly rare, showing a marked contrast between this formation and the two preceding it.

The Coal Measure Group is properly divided into three formations, viz: the Lower, Middle and Upper Coal Measures; each having a vertical thickness of about two hundred feet.

The Lower Coal Measures exists east- ward and northward of the DesMoines river, and also oceupy a large area west- ward and southward of that river; but their southerly dip passes below the Middle Coal Measure at no great distance from the river. This formation possesses greater economic value than any other in the whole State. The clay that underlies almost every bed of coal, furnishes a large amount of material for potters' use. The sandstone of these measures is usually soft and unfit for use; but in some places, as in Red Rock, in Marion county, blocks of large dimensions are obtained, which make good building material, samples of which can be seen in the State Arsenal, at Des Moines.

But few fossils have been found in any of the strata of the Lower Coal Measures, but such animal remains as have been

found are, without exception, of marine origin. All fossil plants found in these measures, probably belong to the class Acrogens. Specimens of Calamites and several species of ferns are found in all the Coal Measures, but the genus Lepidoden- dron seems not to have existed later than the epoch of the Middle Coal Measures. The latter formation occupies a narrow belt of territory in the southern-central portion of the State, embracing a superfi- cial area of about 1,400 square miles The counties underlaid by this formation are, Guthrie, Dallas, Polk, Madison, Warren, Clarke, Lucas, Monroe, Wayne and Appa- noose.

Few species of fossils occur in these beds. Some of the shales and sandstone have afforded a few imperfectly preserved land plants, three or four species of ferns, belonging to the genera. Some of the carboniferous shales afford beautiful speci- mens of what appears to have been sea- weed. Radiates are represented by eorals. The Mollusks are most numerous'y repre- sented. Trilobites and ostracoids are the only remains known of Articulates. Ver- tebrates are only known by the remains of Selachians, or sharks and ganoids.

The Upper Coal Measures occupy a very large area, comprising thirteen whole counties, in the southwestern part of the State. By its northern and eastern boun- daries it adjoins the area occupied by the Middle Coal Measures. This formation contains a considerable portion of shales and sandstone, but the prominent litho- logical features are its limestones. Al- though it is known by the name of Upper Coal Measures, it contains but a single bed of coal, and that only about 20 inches in

HISTORY OF IOWA.

maximum thickness. The limestone ex- posed in this formation furnishes good building material, as in Madison and Fre- mont counties. The sandstones are quite worthless. No beds of clay, for potters' use, are found in the whole formation. The fossils are more numerous than in either the Middle or Lower Coal Measures. The vertebrates are represented by the fishes of the orders Selachians and Ganoids. The Articulates are represented by the trilobites aud ostracoids. Mollusks are represented by the classes Cephalapoda, Gasterapoda, Lamellibranchiata, Brachio- poda and Polyzoa. Radiates are more numerons than in the Middle and Lower Coal Measures. Protozoans are repre- sented in the greatest abundance, some layers of limestone being almost entirely composed of their small fusiform shells.

CRETACEOUS SYSTEM.

The next strata in the geological series are of the Cretaceous age. They are found in the western half of the State, and do not dip, as do all the other formations upon which they rest, to the southward and westward, but have a general dip of their own to the north of westward, which, however, is very slight. Although the actual exposures of cretaceous roeks are few in Iowa, there is reason to believe that nearly all the western half of the State was originally occupied by them; but they have been removed by denudation, which has taken place at two separate periods. The first period was during its elevation from the cretaceous sea, and during the long Tertiary age that passed between the time of that elevation and the commencement of the Glacial epoch. The second period

was during the Glacial epoch, when the ice produced their entire removal over consid- erable areas. All the cretaceous rocks in Iowa are a part of the same deposits farther up the Missouri river, and, in reality, form their eastern boundary.

The Nishnabotany sandstone has the most easterly and southerly extent of the cretaceous deposits of Iowa, reaching the southeastern part of Guthrie county and the southern part of Montgomery county. To the northward, it passes beneath the Woodbury sandstones and shales, the latter passing beneath the Inoceramus, or chalky beds. This sandstone is, with few excep- tions, valueless for economic purposes. The only fossils found in this formation are a few fragments of angios permous leaves. The strata of Woodbury sand- stones and shales rest upon the Nishnabot- any sandstone, and have not been observed outside of Woodbury county; hence their name. Their principal exposure is at Ser- geant's Bluffs, seven miles below Sionx City. This rock has no value, except for purposes of common masonry. Fossil re- mains are rare. Detached scales of a lepi- doginoid species have been detected, but no other vertibrate remains of vegetation, leaves of Salix Meekii and Sassfras creta- ceum have been occasionally found.

The Inoceramus beds rest upon the Woodbury sandstone and shales. They have not been observed in Iowa except in the bluffs which border the Big Sionx river in Woodbury and Plymouth counties. They are composed almost entirely of cal- careous material, the upper portion of which is extensively used for lime. No building material can be obtained from these beds, and the only value they possess,

HISTORY OF IOWA.

except lime, are the marls, which at some time may be useful on the soil of the adja- cent region. The only vertebrate remains found in the cretaceous rocks are the fishes. Those in the Inoceramus beds are two species of squaloid Selachians, or certra- cionts, and three genera of teliosts Mol- luscan remains are rare.

PEAT.

Extensive beds of peat exist in Northern Middle Iowa, which, it is estimated, con -. tain the following areas: Cerro Gordo county, 1,500 acres; Worth, 2,000; W'inne- bago, 2,000; Hancock, 1,500; Wright, 500; Kossuth, 700; Dickinson, 90. Several con- tain peat beds, but the peat is inferior to that in the northern part of the State.' The beds are of an average depth of four feet. It is estimated that each acre of these beds will furnish 250 tons of dry fuel for each foot in depth. At present this peat is not utilized, but, owing to its great distance from the coal fields, and the absence of timber, the time is coming when their value will be fully realized.

GYPSUM.

The only sulphate of the alkaline earth of any economic value is gypsum, and it may be found in the vicinity of Fort Dodge, in Webster county. The deposit occupies a nearly central position in the county, the De . Moines river running nearly centrally through it, along the valley sides of which the gyp-um is seen in the form of ordinary rock cliff and ledges, and also oc- curring abundantly in similar positions along both sides of the valleys of the smaller streams and of the numerous ravines coming into the river valley. The

most northerly known limit of the deposit is at a point near the mouth of Liza d creek, a tributary of the DesMoines river and almost adjoining the town of Fort Dodge. The most southerly point at which it has been exposed is about six miles by way of the river, from the north rly point mentioned. The width of the area is uu- known, as the gypsum becomes lost be- neath the overlying drift, as one goes up the ravines and minor valleys.

On either side of the creeks and ravines which come into the valley of the Des Moines river, the gypsum is seen jutting out from beneath the drift in the form of ledges and bold quarry fronts, having almost the exact appearance of ordinary limestone expo ures, so horizontal and reg- ular are its lines of stratification, and >o similar in color is it to some varieties of that rock. The principal quarries now opened are on Two-Mile creek, a couple of miles below Fort Dodge.

Age of the Gypsum Deposit -No trace of fossil remains has been found in the gypsum or associated clays; neither has any other indication of its geologic age been observed except that which is afforded by its stratigraphical relations; the most that can be said with certainty is that it is newer than the coal measures, and older than the drift. The indications afforde.l by the stratigraphical relations of the gyl - sum deposit of Fort Dodge are, however, of considerable value. No Tertiary do - posits are known to exist within or near the borders of Iowa, to suggest that it might be of that age, nor are any of the Palæozoic strata newer than the subcar- boniferons unconformable upon each other

HISTORY OF IOWA.

as the other gypsum is unconformable upon the strata beneath it. It therefore seems, in a measure, conclusive that the gypsum is of Mesozoic age; perhaps older than the cretaceous.

The lithological origin of this deposit is as uncertain as its geological age. It seems to present itself in this relation, as in the former one,-an isolated fact. None of the associated strata show any traces of a double decomposition of pre-existing ma- terials, such as some have supposed all de- posits of gypsum to have resulted from. No considerable quantities of oxide of iron nor any trace of native sulphur have been found in connection with it, nor has any salt been found in the waters of the region. These substances are common in associa- tion with other gypsum deposits, and by many are regarded as indicative of the method of or resulting from their origin as such. Throughout the whole region the Fort Dodge gypsum has the exact appear- ance of a sedimentary deposit. From these facts it seems not unreasonable to en- tertain the opinion that this gypsum origin- ated as a chemical precipitation in com- paratively still waters which were satu- rated with sulphate of lime and destitute of life; its stratification and impurities being deposited at the same time as clayey impurities which had been suspended in the same waters.

Physical Properties .- Much has already been said of the physical character of this gypsum; but as it is so different in some respects from other deposits, there are still other matters worthy of mention in con- nection with those. According to the re- sults of a complete analysis of Prof. Einery,

the ordinary gray gypsum contains only about eight per cent. of impurity, and it is possible that the average impurity for the whole deposit will not exceed that pro- portion, so uniform in quality is it from top to bottom and from one end of the region to the other. As plaster for agri- cultural purposes is sometimes prepared from gypsum that contains thirty per cent. of impurity, it will be seen that this is a very superior article for such purposes. The impurities are of such a character that they do not in any way interfere with its value for use in the arts.

Although the gypsum rock has a gray color, it becomes quite white by grinding, and still whiter by the calcimining process necessary in the preparation of plaster of Paris. These tests have all been practi- cally made in the rooms of the Geological Survey, and the quality of the plaster of Paris still further tested by actual use and experiment. The only use yet made of the gypsum by the inahabitants is for the purposes of ordinary building stone. It is so compact it is found to be comparatively unaffected by frost, and its ordinary situa- tion in walls of houses is such that it is protected from the dissolving action of water, which can, at most, reach it only from occasional rains, and the effect of these is too slight to be perceived after the lapse of several years. Hon. John F. Duncombe, of Fort Dodge, built a fine residence of it in 1861, the walls of which appear as unaffected by exposure and as beautiful as they were when first erected. Several other houses in Fort Dodge have been constructed of it, including the depot buildings of the Dubuque and Sioux City Railroad. Mary of the sidewalks in the

HISTORY OF IOWA.

town are made of the slabs or flags of gyp- sum which occur in some of the quarries in the form of thin layers.

MINOR DEPOSITS OF SULPHATE OF LIME.

Sulphate of lime in the various forms of fibrous gypsum, selenite and small amorphous masscs, has also been discov. ered in various formations in different parts of the State, including the Coal Measure shales near Fort Dodge, where it exists in small quantities, quite independ- ently of the great gypsum deposit there. The quantity of gypsum in these minor deposits is always too small to be of any practical value, usually occurring in shales and shaly clays. Associated with strata that contain more or less sulphuret of iron, gypsum has thus been detected in the Coal Measures, the St. Louis lime- stone, the Cretaceous strata, and also in the Dead Caves of Dubuque.

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History of Tama County, Iowa, together with sketches of their towns, villages and townships, educational, civil, military and political history, portraits of prominent persons, and biographies of representative citizens, Part 9

Author: Union publishing company, Springfield, Ill., pub Publication date: 1883 Publisher: Springfield, Ill., Union publishing company Number of Pages: 1088

Author: Union publishing company, Springfield, Ill., pub
Publication date: 1883
Publisher: Springfield, Ill., Union publishing company
Number of Pages: 1088