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History of Adair
County, Iowa,
and its People.  1915.

Volume 1.

  
 

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Chapter XXVIII

GEOGRAPHICAL REPORT ON ADAIR COUNTY

By James Willis Gow

The following report by Mr. Gow was written shortly before his death in 1913.  The state department of geology did not know of the existence of the manuscript until it was accidentally discovered among his papers after his demise.  The publishers of the Iowa County History are obliged to the Iowa State Department of Geology and to Prof. George F. Kay, state geologist, for the use of this creditable report.

Adair County is located in the third tier of counties north of the southern boundary of Iowa, and in the third tier east of the western boundary of the state.  It is a square, consisting of sixteen geographical townships, and is bounded on the north by Guthrie County, on the east by Madison, on the south by Adams and Union and on the west by Cass.  To the northeast and northwest it corners with Dallas and Audubon, respectively.  Adair is essentially a prairie county.  Lying well to the south of the Wisconsin lobe, whose moraine passes through Guthrie County, it shows no trace of constructional topography.  It is thoroughly dissected by streams and its drainage system is complete.  Its soil consists of typical Kansas till and its topography is typically Kansan.  The grand divide between the Mississippi and Missouri rivers passes through Adair County in an almost due northwest-southeasterly direction, so dividing it that approximately one-third of the county lies to the northeast of the divide and two-thirds to the southwest.  Owing to the extremely dissected character of the topography, the "draws," or shallow valleys in which the smaller streams take their rise, interlock along the crest of the divide, so that the latter is very crooked.  The county drains on the north and east through North River, Middle River and Grand River; on the south and west through the East and Middle Nodaway rivers.  North and Middle rivers flow into the Des Moines, and so form part of the Mississippi drainage system.  Grand River and the Nodaways flow into the Missouri.  Of these streams, Middle River and Bush Branch (a small tributary of Middle River) are the only ones that cut to bedrock in Adair County.  Grand River cuts through bedrock in Madison County not very far from the county lines.  The Nodaway cuts into bedrock near Mount Etna, in Adams County, and north of that point flows over a clay bed.

PREVIOUS GEOLOGICAL WORK

In 1849 Owen probably passed through the southern part of Adair County, or skirted along its southern border, on his way from Des Moines to Council Bluffs.  In his "Report of a Geological Survey of Wisconsin, Iowa and Minnesota," published in 1852, Owen thus describes this portion of the journey:

"On the Grand River, in the vicinity of Pisgah, nothing but drift is to be seen.  Some miles down the river, however, near a millsite, I was told by the Mormons that a kind of "soapstone" could be found at a low stage of water, which I supposed to be an indurated argillaceous shale; these deposits being popularly known by that name in the west.  This I was unable to examine in person; indisposition, from fatigue and exposure, having brought on a relapse of intermit fever, contracted while exploring the Des Moines.

The distances from Fort Des Moines to Pisgah are as follows:

To the crossing of North River 16 miles
To Middle River 12 miles
To the South or Clanton Fork of Middle River 2 miles
To Clanton's 2 miles
To Big Hollow 14 miles
To forks of road leading to Bellevue 4 miles
To Pisgah 6 miles
 
                Total distance 50 miles

"On the route from Pisgah to Council Bluffs, I crossed Grand River, the Platte Branch of Grand River, two branches of the Nodaway, A Hundred and Two River, and the east, middle and west branches of the Nishnabotna River.  It was only on this latter stream that any rocks were found in place.

The writer cannot find that the memory of any such place as Pisgah lives at this time, though he has not had the privilege of interviewing all the old settlers of the region in question.  From the somewhat detailed table of distance given by Owen the place can be approximately located and it must have been at or near the site of the present Village of Macksburg, in Madison County.  Scattering exposures of shale occur in that neighborhood.  The reference to the mill site would seem to indicate Macksburg as the site of Pisgah.  Owen's journey from Pisgah to Council Bluffs probably took him through the southern edge of what is now Adair County, but in the latter region he found no indurated rocks.

In 1868, White made some observations on the geology of Adair County, and these were published in his "Geology of Iowa," volume I, pages 336 and 339.  In this report he described in considerable detail exposures of carboniferous rock found on sections 11 and 12 in Grove Township, and other points of interest.  White's work is useful to the geologist of the present day and reference will be made to it in the pages of this report.

In the late '70s a geological survey of Adair County was undertaken by Fox, but the work was barren of results and was soon abandoned.

In 1894, Keyes, in the Second Annual Report of the Iowa Geological Survey, reported on the presence of coal in Adair County.  Further reference will be made to this report.

In 1911 Norton and Simpson reported on the underground waters and deep wells of Adair County, in volume XXI of the Iowa Reports.  This article embodies data with regard to eighteen deep wells in various parts of the county.

The writer began work on the geology of Adair County in 1901, under direction of the state geologist, the late Prof. Samuel Colvin.  In 1902 it was found necessary to drop the work for the time being and it was not possible to take it up again until 1912, when it was resumed and pushed to completion.

ELEVATIONS ABOVE SEA LEVEL

The official elevation as given for Greenfield was taken as a standard, the figures being supplied by the officials of the C., B. & Q. Railway, and after the aneroid had been set in accordance with this datum, readings were taken at the other points as indicated below.  The readings for Stuart, Casey, Adair and Fontanelle were verified by comparison with Gannett's Index of Elevations, and were found to be in substantial agreement.

Railway station at Stuart 1,216
Railway station at Casey 1,248
Railway station at Adair 1,442
Railway station at Orient 1,334
Railway station at Greenfield 1,368
Railway station at Fontanelle (old station) 1,244
Railway station at Fontanelle (new station) 1,282
Railway station at Bridgewater 1,188

 

Summerset Township:  
     S. E. sec. 14 1,278
     W. line N. W. sec. 13 1,388
     N. W. corner sec. 13 1,298
     E. line S. E. sec. 18 1,282
Jackson Township:  
     S. E. sec. 34 1,198
Washington Township:  
     S. E. sec. 16 1,155
Union Township:  
     S. E. sec. 16 1,312
     S. E. sec. 1 1,079
Jefferson Township:  
     S. E. sec. 31 1,361
Grove Township:  
     S. E. sec. 19 1,360
     S. W. sec. 1 1,098
     N. W. sec. 12 1,098
Harrison Township:  
     W. line S. E. sec. 18 1,068
     S. E. sec. 20 1,060
     S. E. sec. 21 1,038
     S. E. sec. 27 988
     S. E. sec. 26 943
     S. E. sec. 36 940

EXPOSURES AND DEEP SHAFTS

The C., B. & Q. Railway in Adair County follows the crest of the divide as far north as Greenfield.  The track is very crooked, heads practically every "draw" in the entire twenty miles from Creston to Greenfield, and there are consequently no cuts in that distance.  At Greenfield it drops into the valley of the Nodaway, which it follows as far as Fontanelle, there being some culverts and bridges but no cuts in the seven miles between the two towns.  West of Fontanelle are a few shallow cuts in the drift.

The C., R. I. & P. Railway skirts along the northern edge of the county, and there are a number of rather deep cuts along its right of way.  These never extend below the Kansan drift, but are useful as offering an opportunity to study the drift in vertical section.

The working of the roads in every part of the county has led to the making of many shallow cuts of from two to fifteen feet in depth, and much of the information with regard to the surface clays of the county has been derived from this source.  As a rule it is best to study the cut immediately after it has been made, as a very few rains cause a washing of the clay that obscures things, but very often a few minutes' work with a spade is sufficient to reveal the underlying materials in their natural relations.  Natural gullies developing in pasture and meadows occasionally make it possible to secure information regarding the underlying materials.

The various branches of the Nodaway dissect the western half of the county but do not cut below the drift.  At most points the drift is masked by alluvium, but there are some good exposures.  In the eastern part of the county Middle River cuts through the Kansan drift and into the carboniferous limestone below.  At half a dozen points between Parry's Quarry and the county line the river flows over a rock bottom, the bottom at intervening points consisting of clay, sand or alluvium.  Between the disposition of the carboniferous strata and the advance of the ice sheet was an immense interval of elevations and consequent erosion, and the present exposures of carboniferous rock represent the summits of the hills of the old eroded carboniferous land surface.  The Kansan drift rests unconformably upon this eroded surface.  Nebraskan and Aftonian materials underly the Kansan at many points in Adair County, but no trace of them is to found in the Middle River exposures.

Most of the wells in this county do not penetrate into the bedrock, but merely reach "hardpan" or stiff, impermeable Kansan clay.  The writer secured data with reference to eleven wells which penetrate below the level of the drift, reaching either carboniferous or cretaceous rock.  Besides these eleven, eight more are reported by Simpson in Norton's report on the ground waters of Iowa.  With regard to most of these nineteen wells the available data are extremely meager.  In only one case was a complete and accurate record of the section preserved.  Data regarding the shallower wells are more readily obtained and throw some light on the relations of the various clays, sands and gravels making up the complex Kansan drifts.  It is through an examination of these wells also that the evidence as to the presence of the Aftonian in Adair County has been chiefly brought to light.

There is but one mine shaft in the county, and while it is not now accessible for examination, the writer has been able to obtain an authentic record of this section.

EXPOSURES EAST OF THE DIVIDE

As has been said, the sections east of the divide include only tow classes of material, Kansan drift and carboniferous rock.  The carboniferous rocks of Adair County belong to the Bethany or lowermost member of the Missourian stage.  Rocks belonging to this formation crop out at many points in Southwestern Iowa and Northern Missouri, the name being taken from Bethany, Mo., where they were first studied and where typical exposures occur.  They are characterized by the nodular or fragmental character of some of the strata, by the presence of soft clays and light shales in connection with the harder nodular fragments, while interstratified with these materials are bands of fairly hard massive limestone.  Partings of dark blue or black shale are common, separating the materials just mentioned, and some coal is occasionally present.  Fragmental materials are particularly abundant in the lower portion of the Bethany, the massive limestone being nearly if not absolutely lacking, and this portion has been named the fragmental limestone.  Above the fragmental limestone comes the Earlham limestone, a massive, light colored limestone that breaks or weathers in rectangular blocks and has occasional partings of light shale, while bands and nodules of chert are often present.  Above the Earlham comes, in ascending order, the Winterset, De Kalb and Westerville limestones, these five members making up the Bethany.  The Missourian rocks of eastern Adair County belong to the two lowermost members, the fragmental limestone and the Earlham limestone.

The first exposures investigated are on the west side of Middle River at Perry's Quarry in the northeastern corner of Grove Township.  The rock is exposed in a ravine which approaches the river from the west.  At two points, near the river on the north side of the ravine, quarrying operations have been carried on in the past but were discontinued some years ago.  The bottom of the ravine is flat, being in fact the flood plain of an intermittent brook which has cut in the middle of the plain a narrow gulley some three to five feet in depth.  In the bottom of this gulley is exposed a stratum of brittle black slate.  The section exposed on the south side of the valley, including the slate found in the gulley, is as follows:

10.   Kansan drift  5 feet
9.   Massive limestone, non-fossiliferous,
       rectangular weathering
 4 feet
8.   Soft, light gray shale  1 foot
7.   Limestone, buff to white, with narrow
       partings of light shale
 2 feet
6.   Soft, light gray shale 10 inches
5.   Limestone, similar to No. 7  3 feet
4.   Soft shale, gray to brown  1 foot
3.   Massive limestone without shale  3 feet
2.   Hidden by alluvium 10 feet
1.   Hard, black slate  3 inches
   
                   Total 29 feet, 13 inches

The exposure nearer the river and on the opposite side of the gulley is practically identical with the one just given, except that a band of chert is found in the massive limestone five feet above the foot of the cliff.  At either end the chert is concealed by talus.  It is probably a lenticular mass of no great extent.  Specimens of Athyris subtilita, Spirifer cameratus and Productus nebrascensis were found in the massive limestone of both of these exposures.  The shale is nonfossiliferous.  Some calcite crystals are present in the massive limestone.  The Perry's Quarry exposures are mentioned by White in his "Geology of Iowa," page 336 of volume I, but no details are given.  A third exposure, similar to those at Perry's Quarry, is found in the same section (12, Grove Township) and less than half a mile down the river.  This is in the valley of the little tributary spoken of by White as "Drake's Creek."  The elevation is the same as that of Perry's Quarry and the section is as follows:

4.   Kansan drift  5 feet
3.   Light buff limestone with frequent shaly
       partings, varying in thickness from
       inch to 1 foot
12 feet
2.   Heavy dark cherty limestone  5 inches
1.   Darker limestone, without chert, and
       without shaly partings
 5 feet
   
                Total 22 feet 5 inches

The Perry's Quarry and Drake's Creek limestones and shales are referred to the Earlham formation, the nature and arrangement of materials tallying with that observed in the limestones exposed at Earlham in Madison County.

White, in the "Geology of Iowa," volume I, pages 336-339, dexcribed another exposure on Drake's Creek, which, according to his account, extended twenty-seven feet below the level of the exposure at Perry's Quarry, and the one just given.  Of this I have been able to find no trace.  The section as given by White is as follows:

6.   Black carbonaceous shale, a few inches
       at top consisting of impure coal
 2   feet
5.   Marly clay   foot
4.   Hard, bluish, impure limestone  1   foot
3.   Brownish clayey shale  1   foot
2.   Hared, dark-colored, impure limestone   foot
1.   Fine-grained, micaceous, sandy shale,
      becoming darker and more clayey at
      the top
22  feet
   
                   Total 27  feet

White regarded this as equivalent with the fragmental limestone of Decatur County, and this interpretation is doubtless correct, as the latter includes more or less clay which is sometimes sandy.  While he does not report actual fragmental materials from the Drake's Creek section, the materials reported are strictly similar to those usually found in connection with the fragmental materials at other localities.

Following  on down Middle River, the next exposure is on the Keating farm just above Port Union, and within sight of the mill at the latter place.  On a sloping bank fifteen feet above the low-water level stands a large boulder of hard, well cemented breccia.  Although the hillside is badly masked by drift, an examination shows that the bedrock at this point consists of similar breccia, but the exposure is so unsatisfactory on account of the mantle of drift that it is impossible to say how far up and down the valley it extends.  It appears to dip sharply to the southwest.  The fragments of which this breccia consists are of a fine-grained, light buff limestone, are quite angular, and vary in size fro a quarter of an inch up to eight or ten inches in diameter.  The cementing material is similar but somewhat coarser in texture, and inclined to be crystalline.  A few broken specimens of Athyris subtilita appear in the angular fragments of the breccia.

The third exposure is at the west end of the dam at the Port Union mill.  The sectio is as follows:

5. Black Alluvium 10 feet
4. Yellow till, somewhat gravelly   5 feet
3. Hard, light buff limestone, varying to white or light gray, richly fossiliferous   2 feet
2. Very soft, homogeneous, blue-black shale, richly fossiliferous   4 feet
1. Hard, light-colored, fossiliferous limestone   2 feet
   
         Total 28 feet

Below the dam the stream flows over a rock bottom consisting of limestone No. 1 of the section just given.  At high water No. 2 is covered.  Strata Nos. 1 and 3 bear the following fossils:

Spirifer cameratus.
Productus (fragments).
Crinoid stems in great abundance.
Rhombopora lepidodendroides.
Athyris subtilita.
Fenestalla ---sp.
Myalina subquadrata.
Number 2 of this section (which will hereafter be spoken of as the "Port Union shale") bears the following:
Nucula (centricosa[?]).
Aviculapecten occidentalis.
Monotis (gregaris [?]).
Nuculana bellistriata.
Unidentified gasteropods.
Numerous molluscs.

A complete list of the Port Union fauna must be reserved for a future report.  It is essentially molluscan in its character, and is characterized by the absence of Productids, Spirifers, and crinoid stems, all of which are present in the limestones both above and below, and by the absence of Chonetes verneuilanus, a fossil that is characteristic of the shales farther down the river.

Exposure No. 4 is on the south bank of the river, in section 21 of Harrison Township.  Twenty-two feet of limestone are here exposed.

 
6. Kansan till, blue below, yellow at surface, slightly gravelly in places   5 feet
5. Light-colored massive limestone   1 foot
4. Fragmental limestone, fairly compact below, then with frequent partings of soft clay, finally shading up into a soft purple clay in which but few hard limestone fragments occur 14 feet 6 inches
3. Hard, light-colored fossiliferous limestone   1 foot
2. Soft blue-black shale   2 feet 6 inches
1. Light buff limestone, fossiliferous, largely concealed by talus   3 feet
   
        Total 27 feet

Stratum No. 1 of this exposure bears Athyris subtilita and fragments of an unidentified spirifer.  The only fossil found in No. 2 is Chonetes verneuilanus, but the search was not long continued at this point.  No molluscs were observed.  In color and texture the shale is precisely similar to that found at Port Union.  The limestone fragments of No. 4 are light in color, of variable hardness, and inclined to be angular.  The clay is of about the consistency of the harder Kansan till, or "hard-pan," breaks in the same way, checks on drying, and loses color on exposure to the weather.  The original color is not the blue-black of the shale, but a blue-purple which approximates the color of the deeper Kansan drift.  On leaching it passes through the various shades of purple-brown, dark brown, light brown and yellow-brown.  It is non-fossiliferous, and contains no rock fragments other than the nodular masses of limestone already mentioned.  It seldom shows distinct marks of stratification.  Strata Nos. 4 and 5 are again exposed in a ravine which comes down parallel with the course of the Middle River and enters the latter a few rods below the exposure just described.  The characteristics differ in no way from those already given, except that stratum 5 in two feet or more in thickness.  On a small tributary in section 22 three feet of buff limestone is exposed, the underlying rock being hidden.  In this exposure were found specimens of Productus nebrascensis.

The next exposure is in a narrow ravine on the Pemberton farm in section 27, Harrison Township.  A second section is exposes somewhat farther down the ravine, and the two in combination give the following:

 
10. Kansan till, with small boulders   3 feet
9. Blue clay, similar to that found in stratum No. 4 of the fourth exposure   2 feet
8. Buff limestone   1 foot
7. Fragmental limestone, with much purple clay   6 feet 6 inches
6. Buff limestone   1 foot
5. Fragmental limestone   3 feet
4. Limestone, buff to dark brown   2 feet
3. Hidden by sand, clay and boulders accumulated in stream bed   3 feet
2. Limestone, buff to dark brown   1 foot
1. Dark blue-black shale   2 feet
   
       Total 24 feet 6 inches

Near the top of No. 9 is a band of very brittle black shale about half an inch in thickness.  No. 10 is unconformable upon No. 9, the difference in color and texture being readily distinguishable at a distance of twelve or fifteen feet.  The Kansas here is leached to a light yellow, and bears a few pebbles and small boulders.  The blue clay is non-fossilferous.  The blue shale (No. 1) contains specimens of Chonetes verneuilanus.  This shale is almost black in color and similar in texture to that found at Port Union.  Limestone No. 4 contains an abundance of Rhombopora lepidodendroides.  Many crinoid stems are also present.

In section 26 of Harrison Township the following exposure is found in the valley of a small brook putting into Middle River from the south:

 
11. Gravelly, dark-colored Kansas till   3 feet
10. Hard brown-buff limestone             8 inches
9. Purple clay, weathered brown to yellow   1 foot 6 inches
8. Black, laminated shale, very soft             1 inch
7. Fragmental limestone, grading upward into clay 10 feet
6. Buff limestone with two shale bands   5 feet
5. Fragmental limestone   5 feet
4. Very fossiliferous blue-black shal   2 feet
3. Hard bluish limestone   5 feet
2. Very soft blue-black shale   2 feet
1. Brittle black slate             6 inches
   
        Total 84 feet 9 inches

Stratum 6 of this exposure contains quantities of Fusulina secalicus.  No. 10 is entirely non-fossiliferous.  No. 3 contains Spirifer cameratus, Productus punctatus, P. costatus, P. longispinus, Derbya crassa, Rhombopora lepidodendroides, many crinoid stems and other fossils.  No. 4 contains Chonetes verneuilanus.  The last of the Middle River exposures in Adair County is near the east line of section 36 Harrison Township.  Several feet of blue-black shale occur capped by massive limestone.

On Bush's Branch, in section 13, Grand River Township, occurs the following exposure:

2. Alluvium   3 feet
1. Soft black shale   5 feet

The black shale is extremely rich in specimens of Chonetes verneuilanus which, when the spot was last visited, had weathered out clean and formed a small talus at the foot of the bank.  This is the last of the carboniferous exposures in Adair County.  Near the old mill at the Village of Webster, Madison County, something over a mile east of the exposure found in section 36 of Harrison Township, several feet of rusty-colored Fusulina limestone is exposed, but its relations to the beds above and below have not been traced by the writer.  Probably this represents about the upper limit of the fragmental limestones and their associated clays, shales and massive limestones, and the beginning of the Earlham and Winterset limestones.  As the name would indicate, the latter occur near Winterset, together with the fragmental limestones.  The relation between the three at that point has been described by Tilton in the report on the geology of Madison County, in the publications of the Iowa State Geological Survey.

Except for the anomalous Port Union shales and Keating breccia, the relations of the Missourian strata exposed in the eastern half of Adair County are quite clear.  In Grove Township occur the Earlham limestones, resting on a foundation of fragmental limestone.  (The clay and shale described by White evidently belong to the horizon of the fragmental, though he does not describe the actual fragmental materials.  Their associated clays are characteristic.)  How large a territory is covered by the Earlham in Adair County is impossible to say.  Except at the points indicated it is completely masked by the Kansan drift sheet.  All that we know with certainty is that east of Port Union it was eroded away previous to the deposition of the drift;  the surface rock in all exposures from Port Union to the county line belonging to the fragmental limestone, and closely resembling the fragmental as described by Bain in Decatur County and by Tilton in Madison.  The exposures of Earlham limestone at Earlham, Winterset, Perry's Quarry and other localities, are probably isolated outliers.  In a region so completely covered by drift, the relations of the underlying indurated rocks cannot be worked out with anything like completeness.

In describing the type section of fragmental limestone at Bethany, Mo., Bain ("Iowa Geological Survey," volume VIII) mentions that the lowermost portions of the deposit consist of a hard breccia.  This may be identical with the breccia found on the Keating farm, but the elevation of the latter indicates that it correpsonds with the upper and not the lower portion of the fragmental.  If it is to be regarded as corresponding to the breccia as found at Bethany, the relations of the deposits in Adair County would suggest a north-and-south anticline whose axis would pass somewhere near Port Union.  On the other hand, the Keating breccia may be younger than the Earlham, and may have been deposited after the erosion of the latter, in which case the angular fragments of which it consists are fragments of Earlham limestone weathered from the eroding surface and the cementing material belongs to some later formation.  If the former view be adopted, one may well question the nature of the process that led at one point to the formation of a breccia (for such the fragmental limestone is) whose cementing material is a soft clay, while at the same time and only a mile or two away similar breccia was being formed with a hard calcareous cement.  The Port Union shale, also, with its distinctive fauna, suggests an interval of time between its deposition and that of the other shales here described, which occur at about the same level.  But the limited exposure both of the breccia and the Port Union shale forbids the solution of this problem at the present time.

The general dip of the Earlham limestone and the fragmental limestone in Adair County is toward the south.  Middle River, cutting in a southeasterly direction through these southerly dipping strata, gives them an apparent dip to the southeast.  The apparent southeast dip is of course less than the actual southerly dip.  The former amounts to about ten feet to the mile, or about the same as the gradient of the bed of Middle River.

SECTIONS OF INDURATED ROCK WEST OF THE DIVIDE

The west half of the county is covered by a thick mantle of drift, and no streams cut to bedrock.  Consequently the only obtainable evidence as to the nature of the indurated rocks is to be obtained from deep borings, and the number of the latter records which have been preserved is all too small.  The results indicate that the surface of the Missourian is at places covered by a veneer of Cretaceous sandstone belonging to the Dakota stage.  The following shafts have been investigated:

On the farm of J. A. Hulbert, in Washington Township, 4 miles southeast of Bridgewater, rock was encountered at a depth of 275 feet.  After penetrating through twelve feet of soft sandstone, further drilling was abandoned.

At the residence of J. G. Hendry, one mile south of Bridgewater, a well was sunk some fifteen years ago, and the record, carefully preserved by Mr. Hendry, reads as follows:

Blue clay 65 feet
White clay 40 feet
Gravel   1 foot
Dark, soft sandstone 12 feet
Hard clay, dark in color   2 feet
Sandstone 18 feet
Slate   2 feet
Coal             22 inches
Quicksand and water

 

 
      Total

158 feet 22 inches

The gravel occurring just below the white clay is described as consisting of pebbles which were much water worn and very hard, and of rather uniform size.  The white clay was of such a character as to color the water milky when it was first drawn from the well.  Both it and the blue clay above contained few pebbles.  Eighty feet lower down the hillside and half a mile or less from the site of the first well another shaft was put down with the following result:

Blue clay 177 feet
Red clay with many pebbles 3 feet
Blue-black carboniferous shale 40 feet
 
      Total 220 feet

The black shale contained two or three narrow bands of coal, but was otherwise homogeneous in its nature and of a smooth, even consistency.  The "red clay with many pebbles" is probably a phase of the Dakota sandstone.  In the first section the line of separation between the Missourian and the Dakotan is the two feet of black slate lying immediately above the stratum of coal.

On the farm of E. Stacey, one mile northwest of Bridgewater, in the digging of a well shaft a forest bed was struck at a depth of forty feet.  After taking out a section of a good-sized log, probably of cedar, digging was resumed.  Ten feet lower the auger entered black shale.  The water was dark in color and had a bad taste.  No indication of the presence of cretaceous materials appeared in this well, the drift lying in immediate contact with the Missourian shale.

On the farm of W. W. Witham, in Summerset Township, a short distance west of Greenfield, a well was sunk to a depth of 275 feet.  At about two hundred forty feet the drill passed into limestone with bands of black and blue shale.  No Dakotan gravels or sandstones were present.  The Missourian limestone was covered by 240 feet of blue clay, with some small pebbles and boulders.

A shaft sunk by the City of Greenfield for the purpose of securing a water supply for the municipal electric lighting plant passed through 208 feet of Kansan clay and thirteen feet of Missourian limestone and shale.  No gravels were encountered.  A few small pebbles were found in the clay, and at one point a thin bed of sandy clay was encountered.  As usual, the complete record was not preserved.

A shaft sunk on the farm of F. H. Seers, five miles north of Fontanelle, is reported as passing into soft sandstone at a depth of 260 feet.  About twenty feet of the sandstone was penetrated without noting any change in the nature of the materials.

On the farm of Henry Rose, two miles north of Bridgewater, Missourian limestone was struck at a depth of 270 feet, while a shaft on the farm of Al Bowers, a mile or two north of the Rose farm, passed into Dakota sandstone at a depth of 260 feet.  Forty feet of fine-grained sandstone is also reported from a well bored by William Turner near Adair.

The only record of Dakota sandstone east of the divide is given by Simpson in Norton's report on the underground waters of Iowa.  This is a well bored on the Whittum farm in section 19 of Lincoln Township.

Enough has been said to indicate that the surface of the Missourian rock in Adair County is dotted with scattered outliers of Dakota sandstone.  Probably no part of the county is covered with a solid and continuous mass of cretaceous rock.  The variation in the depth at which rock is encountered indicates tow things:  the depth of the erosion to which the Kansan drift has been subjected, and the depth of the erosion to which the underlying rocks were subjected before the coming of the ice sheet.

The abandoned Eureka coal shaft, six miles south of Adair, passes entirely through drift and Missourian rock.  The shaft is now partially filled, and is not in condition for examination, but was described by Keyes ("Iowa Report," Volume II) as follows in the year 1894:

"The shaft is 262 feet in depth, the coal varying from 20 to 32 inches in thickness.  The roof is bituminous shale.  The bottom of the shaft shows:

Clay shale (exposed) 2 feet
Coal 2 feet
Fire clay           8 inches
Shale, dark (exposed)           4 inches
 
      Total 6 feet

"The mine is worked on the long wall plan.  There are a few unimportant cla seams, but no other breaks in the continuity of the bed.  This is a new mine.  The coal has been taken out only from about one hundred fifty to two hundred feet to the east and west of the bottom of the shaft.  It is reported that there are two other seams below the one now worked, one at a depth of about forty-five feet and the other at a depth of about fifty-five feet from the bottom of the shaft."

In June, 1892, a correspondent of the Greenfield Transcript wrote as follows":

The size of the shaft is 6 by 16 feet and is divided into three apartments.  At the depth of over a hundred feet they found a cedar post.  The dirt passed through was very hard and had to be dug with a pick.  Thence through different kinds of clay and into soapstone.  The caprock is four feet and nine inches thick.  After passing that, came two feet of black looking substance which contained coal blossom;  passing on into slate, thence into a three-foot vein of good coal.  The shaft is 228 feet deep, and the coal is deposited 268 feet from the top of the ground."

The evidence of a forest bed, in the shape of a cedar log, is significant.  The soapstone is probably a smooth, homogeneous shale, such as is characteristic of the Missourian rocks of this part of the state.  No cretaceous rocks appear at this point.  The coal and associated strata here and in the shaft near Bridgewater are probably to be referred to the horizon of the Nodaway coal as described by Smith for the counties south and southwest of Adair, but the formation is so scanty that no definite correlation is yet possible.  If this supposition is correct, the Nodaway coal lies at a considerably greater depth below the Nodaway Valley in Adair County than in Page and Montgomery counties.

THE DRIFT SHEETS

The Nebraskan drift sheet probably underlies the Kansan drift in parts of Adair County, but it is impossible from existing evidence to say anything definite with regard to its extent.  Probably, however, the greater part of the Nebraskan material was eroded away by the advancing Kansan glacier and incorporated in the Kansan drift.  The same may be said of the Aftonian gravels lying on top of the Nebraskan.  The summits of the carboniferous hills were denuded of these materials by the advancing Kansan ice sheet, and they are found today only in those places where the carboniferous rock lies at a low level.  There can be no doubt as to the identity of the Aftonian gravels when found; but it must be borne in mind that the Aftonian did not cover the entire surface of the Nebraskan, but was laid down in the beds of the numerous streams by which the Nebraskan drift plain was dissected during the gradual retreat of the ice sheet.  Consequently there may be many places where the Kansas drift rests directly upon the Nebraskan.  The only wa to demonstrate such a relation between the two is to find them exposed in section and demonstrate the existence of an unconformity; and as the only evidence upon the subject is that obtained from the record of well shafts, such a demonstration is of course out of the question.  Immediately above the Nebraskan and Aftonian comes the Kansan drift.  Through the removal of the earlier deposits the Kansan frequently rests directly upon the bed rock.  Whatever the underlying material, whether Aftonian gravels, Nebraskan drift, Dakota sandstone, or Missourian limestone, there is always of course absolute unconformity between it and the Kansan.  The thickness of the Kansan, and the nature of the materials composing it, may best be indicated by the sections of a number of well shafts investigated by the writer:

1.  On the Conway farm, west of Macksburg in Madison County, but not far from the Adair County line, a well shaft was dug which passed through fifty feet of alluvium and Kansan drift.  For the most part the latter consisted of a stiff, blue clay, unstratified, and without boulders, though containing a few small pebbles.  Below this a bed of sandy clay was struck in which was imbedded a log of hard wood, probably walnut, four feet in diameter.

2.  On the same farm, at about the same depth, the auger entered the bed of rather soft, ill preserved peat.  The peat seemed to consist principally of compacted grass and grass roots, and was roughly but not inaptly described by the well digger as a "fossil haystack."  Above it lay a nodule of brown haematite the size of a goose egg.

3.  On the farm of J. M. Wilson, in section 12, Union Township, a well was dug with the following result:

3. Black surface soil with much humus   1 foot
2. Stiff joint clay, yellow near surface, blue beneath 49 feet
1. Black silt, with many small wood chips   3 feet

The yellow and blue clay was entirely unstratified, contained a very few pebbles and small boulders, and in places numerous lime concretions.

4.  On what is known as the Ed Baker farm, northwest of Macksburg, a well was dug, the auger passing through twenty feet of stiff joint clay, varying in color from yellow to blue-black.  An impediment was then encountered in the shape of a mass of twigs and sticks lying criss-cross and very slightly compacted.  Associated with these were pebbles and bog-iron nodules.  The larger sticks were as large as a man's arm, or larger, and were much broken and apparently gnawed at the ends, but not decayed.

5.  On the Funk farm, northwest of Greenfield, section 2, Summerset Township, the well digger reports that at a depth of twenty-three feet he was obliged to chop through a willow log six inches in diameter.

6.  Some years since the writer watched the boring of a well on lot 3, block 36, original Town of Greenfield.  The auger passed through two feet of black surface soil, then entering yellow-brown joint clay, the upper three inches of which had a slightly reddish cast.  It passed through fifty feet of stiff joint clay, varying in color from yellow-brown to dark blue-brown, absolutely unstratified, and containing no sand, gravel or boulders.

7.  A second well on the same lot passed through thirty feet of stiff blue joint clay without pebbles, sand or boulders.  The lower part of this was the so-called "stinking clay."  The two wells were about a hundred yards apart.

8.  In the northwest corner of section 7, Jefferson Township, a well was sunk to the depth of about thirty feet.  The first twenty feet passed through fine-grained black sand with an admixture of barely enough clay to bind it somewhat.  The auger then entered stiff blue Kansan clay.  The sand is doubtless post-Kansan, and was laid down as part of the old flood plain of Middle River.

9.  In digging a well on the Sears farm, in Jackson Township, a number of logs were encountered at a depth of thirty or forty feet.  The overlying material is unstratified blue and yellow clay with many pebbles and small angular fragments of quartzite.

10.  In a well on the farm of E. Stacey the auger penetrated to the depth of forty feet through stiff blue clay.  At that depth a section of a good sized log of some coniferous wood was removed from the shaft.  After digging an additional ten feet through gravelly clay, black carboniferous shale was encountered.  The water was reported unfit for use.

11.  The city well at Greenfield is bored through 208 feet of stiff blue joint clay, very slightly sandy in places, unstratified, and containing a few small angular pebbles.  This is four blocks distant from the Greenfield well already mentioned.  The Kansan rests directly on Missourian limestone.

12.  In the well on the Witham farm, already mentioned, the clay is reported as having a thickness of 240 feet and resting directly on Missourian limestone.  The clay is blue unstratified showing typical joint structure, and containing a very few small angular pebbles and boulders.

13.  In section 31, Jefferson Township, the writer watched the boring of a well some fifteen years ago.  The well was sunk to the depth of about thirty-five feet, the material consisting of a stiff blue clay, unstratified, and without pebbles below the first four feet, very few being present there.  The material from this well was piled  near the shaft and left there permanently.  In 1911 it was examined by the writer.  The clay still showed the joint texture, but as a result of leaching it crumbled somewhat more readily than it had when first taken out, and the color had changed from dark blue to light brown-yellow.  In fact, as last seen, it was precisely the same soil that many observers have mistakenly supposed to be loess, and that has occasionally been described as loess when reported from Southwestern Iowa.  All that is necessary to the artificial manufacture of loess of this sort is that typical blue joint clay be dug up from the lower portion of the Kansan drift sheet and exposed to the action of the weather for several years.  The surface soil in many parts of Adair County (i.e., wherever it is not covered by alluvium or blackened by plant humus) consits of this leached Kansan clay.  Sometimes it contains pebbles of boulders, more frequently not.  Rarely it is decidedly gravelly.  Lime concretions are not infrequent.  The well just mentioned showed many of them.

14.  Two wells were dug on section 26, Orient Township, under the writer's immediate observation.  The section of one is as follows:

5. Black soil   1 foot
4. Unstratified, yellow-brown joint clay, grading insensibly down into   3 feet
3. Unstratified, stiff blue joint clay, without pebbles or boulders.  This again grades insensibly into   8 feet
2. Blud joint clay, containing numerous angular pebbles and this in turn grades insensibly into the next   3 feet
1. Blue joint clay without pebbles or boulders 15 feet

The shaft of the second well is almost identical with the foregoing except that a very few angular pebbles were scattered through strata Nos. 1, 3 and 4.  Stratum No. 2 shows no signs of stratification, but consists of perfectly typical Kansan clay.

In addition to the foregoing data, the writer has made careful observations wherever the working of the roads has exposed good sections.  The individual points at which observations of this sort have been made it is unnecessary to catalog, since the entire county has been thoroughly covered in this respect, and the results everywhere agree.  The surface soil, everywhere except where covered by alluvium or modified by the presence of abundant plant humus, is a joint clay, that is, a clay that when crushed dry in the fingers becomes coarsely granular in texture.  It is usually light in color, varying through the shades of brownish yellow and brown.  No surface soil has been found that has the peculiar smooth "greasy" consistency characteristic of the Iowa and the Missouri loess, nor has any been found that blows up in the fine, impalpable dust characteristic of the loess.  The granular surface clay, when exposed in a fresh cut, sometimes shows lime nodules, sometimes not.  Where it has been penetrated by plant roots the latter are sometimes surrounded by iron, and the soil at the lower limit of the portion penetrated by the grass roots sometimes shows a reddish streak.  It is never fossiliferous.  Pebbles and small quartzite fragments as large as one's two fists are not uncommon, large boulders are occasionally present, and very frequently it is --- like the underlying blue clay --- entirely without stone fragments of any sort whatever.  When pebbles and boulders are present they are usually very angular.  The largest boulder the writer has seen was one about three feet in diameter on section 31, Jefferson Township, and in Greenfield a number of quartzite boulders two feet in diameter are used as cornerstones and hitching posts, but stones of this size are extremely rare.  This yellow joint clay grades down insensibly into the stiff blue clay beneath, and it is impossible ever to draw a definite line of separation between the two.  In fact, when the stiff blue clay is exposed at the surface the action of the weather leaches it out to a yellow tint, it becomes somewhat more porous and takes on all the characteristics of the surface clay as here described.  In view of these facts the writer is driven to believe that they are in fact identical.

To sum up:  The lower Pleistocene of Adair County consists of a thin sheet of Nebraskan till, most of which may have been removed or incorporated into the Kansan, and a sheet of gravels and silts representing the Aftonian interglacial period.  The latter is present at many points in the county, under the thick Kansan drift, as evidenced by the presence of a forest bed containing logs of a variety of species of trees and also by the presence of stratified gravels, sand and peat, and frequent iron nodules.  The cases mentioned here in detail are but a few of many that might be found.  So general is this condition that well diggers tell the writer that below a depth of thirty-five or forty feet they "expect to strike logs," and the Aftonian gravel is well recognized among local well diggers as a water bearing stratum.  Mr. Jesse Hines, a veteran well digger residing in Greenfield and well known to the writer for many years, writes thus:  "We find pieces of wood in this county anywhere when we go down through blue or black clay."  Many other well diggers bear witness to the correctness of this statement.  Above the Aftonian lies the Kansan drift, of variable thickness, depending upon the two factors of pre-Kansan erosion and post-Kansan erosion, but at least two hundred seventy feet at its maximum.  This is a heterogeneous mass of clays, sands, gravels and boulders, the various materials being arranged in no discoverable order.  They never show signs of stratification, nor do they at different points in the county sustain a uniform relation to each other.  The materials lie as they were left by the ice, and are, as one would expect, absolutely heterogeneous.  Large boulders are rare, smaller fragments not uncommon, the prevailing stone being Sioux quartzite.  Sands and gravels are not very common.  The typical material is stiff blue joint clay, which on exposure to the weather becomes lighter in color except where stained by iron or darkened by products of vegetable decay.  The blue clay varies in density.  When very dense it becomes, when once wet, impermeable by water from above, and is known as hard pan.  The hard pan grades insensibly into the softer clay above and below.  It sustains no constant to the other materials and may be found at any depth.

POST-PLEISTOCENE DEPOSITS

The post-Pleistocene materials occurring in Adair County may be classified as alluvium, stratified gravels, stratified sands, and peat.  Of these, the first three belong together and are associated with the flood plains of the larger streams.  It should be added, however, that many smaller streams, ever of an intermittent character, have fairly well defined valleys with flood plains a few rods in width, while others have failed to broaden their valleys in this way, and have cut mere gulleys in the Kansan plain.  It is of course impossible to indicate the location of narrow alluvial bottoms along the course of the smaller prairie streams.

Typical alluvium as found in Adair County is when dry a very dark gray-brown;  when wet it becomes black.  It is usually more or less distinctly stratified.  Occasionally sand and alluvium are found interstratified, the former of course representing an old bar, the latter being laid down on top of the bar after it had become a part of the overflow plain, through the deepening and shifting of the stream's course.  The flood plain is usually broader on the north and east sides of the valley than on the south and west.  In the former case it slopes gently back to the hills bordering the valley;  in the latter case it usually forms a more acute angle with the hills at their base.  The hills to the south and west have a steeper gradient than have those to the north and east.  The latter slope southwesterly and face the noonday and afternoon sun.  The former are shaded during much of the day, and consequently hold the frost longer in the spring and are not so subject to erosion.  This variation in the contours of two sides of a valley is constant throughout the county for all the larger streams.  The best sheltered flood plains are on the right hand side of the valleys, and it is there that the timber is densest and there the moisture-loving and shade-loving plants flourish most luxuriantly.

An interesting deposit of stratified gravels and peat is found on the Burrell farm, two miles southwest of Greenfield.  At the extreme edge of the flood plain of a small tributary of the East Nodaway, a gravel pit has been sunk to a depth of eight feet.  On the side toward the hill the gravel is distinctly stratified with much cross-bedding.  On the opposite side, next the flood plain, the section shows a more uniformly horizontal stratification without cross-bedding, the material being the same coarse gravel mixed with many nodules and cysts of bog iron, the whole bound together by layer after layer of coarse dark colored peat.  The peat is very recent, as is evidenced by the fact that the topmost layer forms the present ground surface and shows the hummocks characteristic of the slough grass growing here before the bottom was sowed to blue grass.  The peat consists merely of layer after layer of solidified or semi-solidified grass roots to the thickness of about five feet.  Many of the tinier roots are more or less intact and are surrounded by red tubules of bog-iron.  The hollow bog-iron cysts so common at this point are frequently filled with a matted tangle of grass roots.  The cysts vary in size from the size of a hazelnut up to ten or twelve inches in diameter.  The pebbles making up the gravel exposed at this point are extremely waterworn, more so than those usually found in the beds of streams cutting through the Kansan drift.  Their rounded condition, and the fact that quartzite fragments are not present, would suggest an Aftonian origin.  The writer suspects that this gravel deposit was originally an Aftonian boulder, ploughed up by the Kansan ice sheet in its advance, and buried in the Kansan till.  Subsequent erosion cut the valley, and in doing so cut through one side of the boulder.  Owing to a local imperfection in the post-Kansan drainage system, however, the material was not carried down into the Nodaway, but was caught in a small bog at the foot of the hill and there re-deposited with horizontal stratification.  Much coarse grass was growing in the bog, and the peat thus formed was interstratified with the gravel washed down from the hillside.  Haematite cysts and nodules would necessarily form under these conditions.  The area of the peat may be traced to the alluvial bottom by the poor growth of the blue grass, and the fact that it is of a much darker color than is the surrounding grass.  The little peat bog is only a few rods in diameter.  It is interesting to note that this tiny and inconspicuous peat bed was discovered by White and is noted by him in his geology of Iowa.  He did not, of course, discover the gravels, as they were not uncovered until 1910.

Another peat bed is known to the writer, in the northeast corner of Walnut and northwest corner of Jefferson townships.  This is a part of the flood plain of Middle River and was originally covered with hummocks of coarse slough grass.  It was an area of imperfect drainage, about thirty rods in diameter, doubtless having been originally an ox-bow lake and having been filled up by successive crops of grass.  Years ago this was turned into a pasture and the blue grass turf finally covered it.  A well sunk in the turf to a depth of three feet gave an inexhaustible supply of extremely clear water.  In wet seasons the place showed a tendency to revert to its boggy condition, owing to the fact that the cattle tramped out the turf, and it was decided to drain the bog into Middle River.  The ditch was dug to a depth of five feet, through a rather coarse, but densely compacted dark brown peat.  Doubtless many peat bogs of this sort might be found along the alluvial plains of the larger streams.

PALEONTOLOGY

The shells of modern land snails are frequently found in the alluvium of flood plains and terraces.  No systematic investigation of these has yet been made, and the subject must be reserved for a future paper.

The joint clay which makes up the greater part of the Kansan drift sheet is entirely non-fossiliferous.  Many species of land molluscs dwell on the surface of the drift and are often buried by caving banks or become covered by the humus which forms a veneer over the surface, but careful search has failed to reveal any imbedded in the body of the drift.  The leached portions of the drift sheet, which has been sometimes mistakenly described as "loess" is non-fossiliferous equally with the deeper and more compact clay.

Owing to the extremely limited opportunities for observation nothing is known as to the fossiliferous character of the Dakota deposits in Adair County.  No fossils are reported from the few shafts which penetrate this formation.

The Earlham limestone contains the following species:

Productus nebrascensis.
P. punctatus.
Athyris subtilita.

The massive ledges found below the level of the Earlham in connection with the fragmental limestone, reveal the following fauna:

Productus nebrascensis.
P. cora.
P. costatus.
P. punctatus.
P. longispinus.
Spirifer cameratus.
Athyris subtilita.
Fenestella --------- sp.
Rhombopora lepidodendroides.
Allerisma terminale.
Derbya crassa.
Fistulipera nodulifera.
Fusulina secalicus.

The blue shale associated with the foregoing limestone is particularly rich in Chonetes verneuilanus.

The Port Union shale contains a rich and distinctive fauna,of which only the following can be here given:

Aviculapecten neglectus.
A. ---------- sp.
Myalina subquadrata.

Owing to the extremely soft and brittle character of the Port Union shale, the securing of perfect fossil remains from it is very difficult, but it is extremely fossiliferous, and will repay future investigation on the part of the paleontologists.  In the Keating breccia were found remains of Athyris subtilita, and an unidentified Productus.

ECONOMIC GEOLOGY

In an earlier day much limestone was quarried from the Earlham and the thin ledges of massive limestone associated with the Fragmental, but the cheapening of cement construction has driven the limestone out of use.  For a limestone, the Earlham resists the action of rain and frost excellently.  Many foundations and one stone house forty years old bear witness to its enduring qualities.  For purposes of construction, the Fragmental proper is of course worthless.  The massive limestone will be marketable for macadam and concrete construction as soon as the Port Union country shall be opened up by the advent of a railroad, but the Fragmental cannot even be used for this purpose, since it contains too great an admixture of carboniferous clay.  The Port Union shales, and the other blue shales cropping out farther down Middle River are of smooth, even consistency, without grit, and with the limestone should make a cement of good quality.  This industry also awaits the coming of a railroad to make it profitable.

The brick industry in Adair County goes back to the very early times.  At a very early day there were brickyards at Fontanelle, Adair and Casey.  About thirty years ago there was a brickyard just west of Greenfield, north of the old Fontanelle road which is now Main Street, and at the same time the Day Brickyard was in operation a short distance east of Fontanelle in the Nodaway bottom.  In all these cases the brick was molded by hand, and was of rather inferior quality as measured by the standard of today, being rough and soft.  About fifteen years ago, a brickyard was established in Greenfield by J. W. Darby, and for a decade an excellent quality of brick and tile was manufactured at this point.  The material used in the early manufacture of brick in the county was the black alluvium of sloughs and stream bottoms, since it was then believed that the joint clay was useless for this purpose.  In fact, the latter cannot be used successfully where the method of molding by hand is in vogue, since it will check in drying and experience has shown that most of the brick are ruined.  It often has the added disadvantage of containing many small pebbles, which of course makes its use for brick making impossible.  The material used by Mr. Darby was a deposit of drift, of joint clay, lying just east of the railway station in Greenfield.  At this point the drift is practically free from pebbles.  One large boulder was uncovered in the diggings, and in a search of an hour covering the exposure the writer found three tiny flint pebbles.  The brick and tile were molded by machinery and it was found that there was but little checking and very few were spoiled in the burning.  Mr. Darby maintained a permanent equipment of one large brick kiln and three tile kilns, the product being taken as soon as made, and the demand usually exceeding the supply.  The establishment finally passed into other hands and the business having become involved, was discontinued in a few years.  The machinery was bought by C. H. Cass of Bridgewater.

Mr. Cass was a contractor and bricklayer and maintained a yard at Bridgewater where he manufactured the materials used by him.  The material used was ordinary Kansan drift clay, which in the vicinity of Bridgewater was commonly free from pebbles and sand, and burned into excellent brick.

The brick and tile industry in Adair County offers good possibilities.  There are large plants at Creston and Stuart, but owing to railroad disadvantages there are no large ones in Adair County.

CHANGES INCIDENT TO HUMAN OCCUPATION

Open pastures in all parts of the county show much recent erosion, the gulleys cutting from a depth of a few inches to fifteen or twenty feet, and gradually backing up from the lowlands toward the higher ground.  So general is this process and so recent is it in all observed cases, as to lead to the suspicion that the region may have undergone recent rejuvenation.  After careful examination the writer has been led to reject the rejuvenation theory.  It is noticeable that the process of gully cutting takes place only in those places where the wild grass has been replaced by the tame grass.  Blue grass pastures are especially subject to dissection of this sort, while the process is absolutely unknown in those places where the native slough grass still carpets the soil.  It must of course be remembered that the slough grass is not limited to bogs and marshes, but is the normal ground covering in all shallow sloughs and draws, even when the latter lays close to the crest of the divide.  Originally, therefore, every place that would, by reason of its lower level, be the natural starting point for the development of a gully, was covered by the slough grass.  This grass grew in hummocks, which usually lie so close together that one may step from one to the other.  It roots very deep (three to six feet) and the root system forms a dense spongy mass that absorbs water readily.  The decay of the culms and the older roots forms a very absorbent humus and because of the dense root mass this humus does not wash away, but remains and so increases the absorbent capacity.  The grass grows very thick, to a height of three to four feet, producing a dense shade, and thus reducing evaporation.  The roots are not limited to the hummocks or stools, but penetrate between and the whole slough thus becomes a great tough sponge for the retention of moisture.  Under these conditions rapid erosion is an impossibility.

When the slough grass has been replaces by blue grass, most of these conditions are reversed.  The blue grass makes, it is true, a dense ground cover, but it does not root deeply and it does not produce a heavy humus.  Especially is the latter true in the case of pastures where the grass is continually eaten off short.  Once erosion is started at one point it proceeds with great rapidity.  The soil beneath the turf (and the latter is but a few inches in thickness) is quickly washed out, the water excavates beneath the edge of the overhanging turf, and the latter soon begins to break off of its own weight and fall into the little gully thus forming.  Each rainstorm deepens the gully a little, and backs it up a few feet, until finally the greater part of a valuable pasture may be dissected by a series of several wide, deep gulleys and many square rods of pasturage destroyed.  In the wasteful farming of the past, farmers and agricultural teachers have alike failed to estimate at its full value the damage to the agriculture of Iowa wrought by this process.  In the more economical farming of the future, effective means will have to be taken to check it.  The cultivation of the soil has, of course, greatly increased the factors of creep and sheet-water erosion, denuding the higher ground of much of its humus, and increasing the thickness of alluvium on the lower lands.  To a certain extent this is unavoidable, but true economy would suggest that the steeper hillsides should not be ploughed, and should be kept in permanent meadow or pasture.  The annual run-off has also been greatly modified by cultivation.  Under primitive conditions the water of the spring rains was caught by every slough and held through the season, gradually seeping out, as the summer went on, to feed the smaller streams.  The whole land surface was dissected by this network of reservoirs which, by reason of the conditions of shade, humus, spongy consistency and depth of root mass, etd., made an excellent series of feeders for the streams.  Under present conditions the run-off is much more rapid in the spring and this is likely to be succeeded by a condition of semi-aridity during July and August.  It is no unusual thing for Middle River and the East Nodaway to cease flowing during August, the water being reduced to a few shallow pools.  In the summer of 1911 the writer walked for half a mile down the bed of Middle River and not only found no water, but in that distance found the sand for the most part perfectly dry and dust-like.  Above and below this half-mile stretch were stagnant pools, and there may of course have been a little seepage through the lower part of the sand, but could not have been much.  Such is the condition in a year of drought.  Conditions of this sort were unknown in the early days before the breaking up of the prairie and the extirpation of the native grass.

The cutting of much of the timber has had a marked effect on erosion and topography.  It is true that much good land has been added to the cultivable area.  On the other hand, much land has been cleared that ought to have been left in timber.  The clearing of the steeper hillsides has led to the washing away of the humus with which they were once carpeted.  This having once occurred the grass becomes thin, gullies begin to develop, and soon the entire slope is dissected by deep V-shaped valleys and is perfectly bare of vegetation.  If, after clearing, the attempt is made to put a slope of this sort under the plow, the process is of course hastened.  In any case land which was originally productive becomes waste and then cannot be farmed, nor can it be reforested without tremendous expense.  True conservation demands that the rougher land be kept in timber.  The destruction of the brush and the smaller forest vegetation has led to much destructive erosion on the steeper slopes.  A blue grass surface, covered with sparse timber is readily cut into gullies in the same way as are open pastures though not at the same rate.  In clearing ground the brush should be left on the steeper slopes.  With the increasing value of timber, and the advanced price of land, the problem of woodland conservation should no longer be ignored.

BOTANY

The relation of botany to geological conditions is always a close one, since the nature of the plant covering and the distribution of plant species depends very largely upon the character of the mantle rock.  Conversely, the nature of the vegetation may profoundly modify the ground conditions.  The flora of the county comprises a number of fairly distinct types, and these types conform in a general way to the three conditions of moisture, shade and soil.  In general these types may be classified as follows:

 
Prairie Upland prairie flora  --- xerophytic to mesophytic. High gravel points.

High exposed south and west slopes --- partially xerophytic.

North and east slopes --- xerophytic to mesophytic.

Slough flora. Slight depressions in high prairies --- mesophytic --- and intermediate stages down to wet bogs on lower levels --- hydrophytic.
Prairie stream flora. Hydrophytic flora, bordered by thin fringe of mesophytic flora.
Unforested alluvial bottoms. Mesophytic on higher grond.  Hydrophytic in bogs and oxbows, and near streams.
Native Forest. Steep bluff flora, usually on south or west bank of larger streams --- mesophytic.

Ravine flora, found low in gullies cut in river bluffs, and at the base of bluff's --- mesophytic to hydrophytic.  This includes much the same species as the next.

Shaded alluvial bottoms --- mesophytic to hydrophytic.

 

 

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