History of Fillmore County, Including the Explorers and Pioneers of Minnesota, Part 48

Author: Edward D. Neill
Publication date: 1882
Publisher:
Number of Pages:

USA > Minnesota > Fillmore County > History of Fillmore County, Including the Explorers and Pioneers of Minnesota > Part 48

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The St. Lawrence, in Fillmore county, is a dolo- mitic limestone, with some of its layers distinctly arenaceous, and stained with green sand. In gen- eral, its bedding is regular and evident, but there is a thickness of about fifteen feet near the bottom of the formatiom in which the bedding is con-

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fused, or the layers are lost horizontally. Below this confused bedding are, however, about twenty- five feet of regular beds, which have a fine even grain, and though not plainly arenaceons, yet have a very fine grit. On fresh surfaces it is of a buff color, varying to cream color. The upper portion abounds in patches of white calcite. There are also in the upper portion spots that show thin, con- centric, though wavy, laminations, as if from con- cretionary forces, or the result of silicified masses of foraminifers, reminding the observer of the laminated masses of limestone from the Laurentian containing the Eozoon Canadense of Dr. Dawson. Though the most of the rock of this formation is vesicular, often coarsely so, it is much used for building, for which it furnishes both large blocks for the heaviest masonry, and fine-grained stone that can be cut into delicate forms. When cut for window caps or sills the cut surfaces are nearly white. The bedding varies in thickness from two or three inches to two or three feet, and sometimes embraces thin beds of shaly, light-colored, fine grained rock that is useless for all purposes.

At Clear Grit Mills, in the valley of the Root River, the St. Lawrence begins to show a con- tinuous line of bare rock, in the river bluffs run- ning along the lower slopes, and causes a shoulder or terrace in the general descent. A quarry near the mill-dam shows abont fifteen feet of even lay- ers, Above these are the layers represented in the railroad cut near that place. These are light col- rred, dolomitic, vesicular, abounding in patches of calcite with some chert, and siliceous concretions, the latter sometimes covered with limonite pesu- domorphous after pyrite. The cut exposed the following materials:

Loess Loam, 3 feet, red. Drift Gravel, 4 feet, red. Jordan Sandstone, 16 feet, red. St. Lawrence Limestone, 30 feet.

At Whalan the St. Lawrence is finely exposed in the bluff that stands in the valley about half a mile below the village. It has here been con- siderably quarried, and furnishes a very good stone for buildings. It lies in even layers, which ' are easily broken into desirable size and shape, furnishing a good cut-stone of close grain, with- out openings. Of the 155 feet that here overlie the St. Croix sandstone, only the lower portion is well exposed. The exposed layers are separated from those scen at the quarry at Clear Grit by an

interval of fifty feet. They consist of the follow- ing parts, aggregating sixty feet:

1. Slope, Lid by turf (St. Lawrence) ..... 95 feet

2. Heavy beds, even grained, vesicular, the

best general building stone. .. 20 feet

3. Bedding confused, not evident, lenticu- lar 15 feet

4. Fine grit, regular beds, dolomitic. . . 20 feet

5. Hard arenaceous, projecting, fossilifer-

ous with the remains of trilobites. . . 5 feet

At Lanesboro the St. Lawrence has been used in the construction of the principal buildings. The quarries are owned by the Lanesboro Com- pany. The stone presents the usual characters, but has associated masses of pyrite, largely con- verted to limonite, showing octahedral forms of crystals, with combinations. In some of the cherty nodules are found small orthorhombic crystals of hydrated iron peroxide, formed by the conversion of marcasite into limonite. This iron ore is quite plentiful, but seems not to be a native of the rock. It embraces crag and bog-ore deposits, and is re- ferable to the drift period.

THE JORDAN SANDSTONE .- This sandstone, lying next above the St. Lawrence limestone, is not so frequently seen along the river bluffs. It is most commonly embraced in that interval of slope that comes between the two lines of limestone outcrop, and which is mostly turfed over, as in the bluffs at Lanesboro, and at points between Preston and Lanesboro. Further down the river, where the strike of the Shakopee runs back from the river a few miles on either side of the valley, it occupies the undulating surface between the -immediate river bluffs and the boundary of the Shakopee, as at Rushford. This sandstone, in the Minnesota valley, has been mistaken for the Potsdam, the overlying Shakopee being supposed to be the lower portion of the lower Magnesian.

In Fillmore county the thickness of the Jordan is not so great as it is in the Minnesota valley. It seems to vary from 25 feet to 40 feet. At Man- kato, in Blue Earth county, it is fully fifty feet thick. It is uniformly a coarse grained, quart- zose, crumbling and light. colored sandstone. It is sometimes locally stained with iron from sur- face water, when it presents a reddish or rusty color, and is apt to be much harder. It has in such cases a shell or thin coating of harder rock, about half an inch in thickness, on the weathered surfaces, on penetrating which the grains are

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loosely cemented, and even crumbling. In other places it presents internally a streaked appearance, due to the stoppage of iron filtering through its strata. No fossils have been found in it.

One of the best exposares for examining this sandstone may be seen at Preston, where it rises 25 feet above the level of the river opposite the stone mill, and is surmounted by about 35 feet of the Shakopee limestone. The bluff itself rises about 95 feet above the river, but the contents of the upper portion, though probably of the Shako- pee, are not certainly known. The loam covers it. The bedding of the stone here is regular, though in some places a little wavy, and is of all thick- nesses, from a foot to three or four inches.

At Lanesboro the Jordan exhibits, near the top, a finely concretionary structure. The balls vary from a few inches to nearly a foot in diameter. Some of them are elongated, and several are fre- quently united. The rock itself is generally friable, and crumbles out, leaving the concretion- ary shapes visible. They are often loosened, and roll down the bluff. They lie in approximate layers for a thickness of four or five feet. Some of them are pendant from the projecting shelf, and stud the whole under surface. They are gen- erally spherical, but when they are lengthened perpendicularly they show the original lamina- tion that ran through the rock, in the form of rings and furrows.

At Clear Grit the Jordan is 25 feet thick, and is exceedingly ferruginous. At Lanesboro it is about forty feet thick.

THE SHAKOPEE LIMESTONE .- This is the upper- most member of the Lower Magnesian, and is so named from the village of Shakopee, in Scott county, on the Minnesota River, where it was first identified as a distinct and entire member of the great Lower Magnesian Formation. In Fillmore county it is more frequently seen along the valley of Root River and its tributaries than any other formation. As it lies between two sandstones, each of which easily crumbles away under the op- erations of the elements, it is made to have a prominent position in giving form to valleys and river bluffs. The north branch of Root River enters on it about six miles northwest of Chatfield, in Olmsted county; the middle branch near the town line between Chatfield and Jordan, and the south branch but a short distance below Forest- ville. South Root River strikes it near Henry, in Amherst township. Thus, throughout about two-

thirds of the county, it is the constant companion of the traveler along the river valleys, and it meets him often in the uplands, and in the valleys of little creeks. Its effect on the topography is to render the valleys narrow, rocky, and abrupt. Within the general area of the St. Peter sandstone and the Trenton limestone, it produces a shoulder in the descent from the uplands to the valley. A diagram taken at Chatfield along the northern boundary of the county, would show the strata superimposed in this way :

Loam 6-10 feet

Upper Trenton 20-50 feet

Green Shale. 15 feet

Lower Trenton 20 feet

St. Peter. 122 feet

Shakopee.

30 feet

Flood Plain.

The descent. from the general level of the coun- try at Chatfield to the river is about 222 feet, of which about 30 feet are of the Shakopee, the de- scent from the Shakopee to the river being at the river. The broad terrace on which Chatfield stands is constituted of the Shakopee overlain by irregular thicknesses of the St. Peter, with some drift and loam. The lithology of the Shakopee is very much the same in Fillmore county as it has been described in former reports at Mankato and Shakopee, in the Minnesota valley. It is very similar to the St. Lawrence, with much less of green sand. It contains at Chatfield considerable disseminated sand, and nodules of calcite. The calcite is sometimes purely transparent, so as to exhibit the double refraction of Iceland spar, parting into large rhombohedrons, but the most of it is opaque. It is sometimes interspersed with sand grains taken up in the process of crystaliza- tion. These are so abundant as to make, of some crystalline masses, a sandstone which is then nod- ular and hard, with warty projections.

A general profile section of the valley of Root River would show:

Upper Trenton.

Green Shales.

Lower Trenton.

St. Peter.

Shakopee.

Jordan.

St. Lawrence.

At Parsley's Ford, center of section fifteen, Chatfield, a bridge is built over the river, the

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abutments being of the Shakopee stone taken out near the ford, on Mrs. Doyle's land. At the ford the river is on the Jordan sandstone. There has been considerable stone cut off the bluffs, in the Shakopee, for use in the railroad bridge near the same place, and laid up in heavy blocks; but much of the Shakopee is in irregular and thin layers, unfit for such use.

At almost any point east of Chatfield and Cari- mona, the Shakopee can be seen by one crossing the valley of Root River, exhibiting its peculiar tendency to narrow the valley, and forming a con- spicuous bench or shoulder. At Preston the rocks show a dip to the south.

At Isinours station the battlements of rock that enclose the valley, rising about 30 feet above the water, are of the Shakopee. There is an undu- lating ascent thence over the St. Peter to near the Trenton terrace, which rises nearly perpendicular about 50 feet. Beyond this is a flat, running sometimes but 8 or 10 rods, but not infrequently a quarter of a mile, when a further gradual ascent begins, covering the Green Shales and the Upper Trenton. This last ascent, with the loam that here covers the country, generally makes about 175 feet.

At Carimona, the Shakopee is visible in the banks of the river, rising 25 or 30 feet. Its average thickness is about 75 feet.

THE ST. PETER SANDSTONE .- The thickness of this well-known formation in Fillmore county does not vary much from its reported thickness in the central portion of the State. It has been taken at 125 feet. At Chatfield, it measures, by aneroid, 122 feet. In lithological characters it is also the same, consisting of clean white sand that easily crumbles. Near Fountain, an exposed section near the top of the formation afforded fragments of an unknown species of Lingulepis, the first and only fossil of any kind that has ever been found in this rock. The following section was taken at this place. It includes the overlying lower Tren- ton, and the Green Shales, as seen at the quarry of Mr. Joseph Taylor, section thirteen, Fountain. No. 1. Green shale, mixed with fragments of limestone that are eminently fossiliferous. 3 feet

No. 2. Limestone, of a bluish-gray color, in beds from four to six inches thick, free from Shale, though the layers are sometimes thinly separated by shaly partings. ... 10 feet

No. 3. Arenaceous and ferruginous shale, alternating horizontally with firmly cemented patches of sand- stone .. 2 feet

No. 4. Massive, coarse sand; white, except where iron stained, containing irony quartzite pebbles, and frag- ile remains of bivalves. . . ..... 6 feet No. 5. Green shale, with some arenaceous and calcareous laminations. 3 feet

No. 6. Cemented sandstone, the cement being shale and lime, forming, when the bluff is weathered, the floor of a bench. 1 foot

No. 7. White sand, in beds that are about one foot thick, and horizontal .. 6 feet

No. 8. A course in the sandstone more firmly cemented, forming another table, but less persistent than No. 6. 1 foot

No. 9. Massive sandstone, in some places showing an oblique lamination,

Been 6 feet

The Southern Minnesota railroad here enters on its descent to the Root River valley.

The species of Lingulepis mentioned is found in the St. Peter of the foregoing section. The re- mains are exceedingly fragile, and as the grains of sand in which they are embraced are feebly cemented together, it is nearly impossible to transport, or even to handle them without their falling to pieces. These fragments, for no entire specimens were obtained, are arranged promiscu- ously in the coarse sand, and are all confined within three feet of the top. They seem to have suffered the attrition and friction incident to coarse sedimentary transportation. They dispel the idea, which has been suggested, of the possible chemical origin of the St. Peter sandstone, as an oceanic precipitate.

Description .- Shell conical or elongate-conical, with anterior angles rounded; depressed; the apical angle not seem perfect; the front margin gently convex; sides nearly straight, but converg- ing at an angle of about 26 degrees; greatest width is near the front and at a distance from the anter- ior margin of one-third the greatest width. The surface is smooth and shining, marked with very fine concentric striæe, visible especially in the anterior portion, and with more distant, dim, un- dulations of growth. Color of the shell light brown, with spots of brown. The smaller speci-

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men has flattened, or slightly concave margins, for nearly two-thirds the length from the apax. This species in general contour resembles Lingule- pis Briseis, of Billings, (Paleozoic Fossils, Vol. 1, p. 48,) but differs from it in not having its sides parallel.

Locality and Formation-Near Fountain, Fill- more county. Upper portion of the St. Peter sandstone. Named in honor of Prof. E. S. Morse.

The remarks that have already been made on the topography of the county will sufficiently elucidate the nature of the St. Peter, and its im- portant part in the causes that have diversified the surface of Fillmore county.

THE TRENTON LIMESTONE .- This formation is the most important one in the county, both on account of the great superficial area it embraces, and because it appears in numerons places under the most favorable circumstances for working for quicklime and for building stone. It is likewise the most conspicuous of all the formations, es- pecially along the line of its strike, where it gives way, and the surface falls rather suddenly on to the lower level of the St. Peter sandstone.

The term Trenton limestone is here made to cover a thickness of rock of about 160 feet, and to embrace, within the limits of Fillmore county at least, three distinct members, of which the upper- most is the principal portion.

Upper Trenton limestone 125 feet

Green shale. 15 feet

Lower Trenton limestone. 20 feet

The transition from the St. Peter sandstone to the lower Trenton is quite abrupt. There is no commingling of qualities from the Trenton down- ward into the St. Peter, although a shaly layer of about two feet separates them. The limestone always projects boldly beyond the sandstone, and the sandstone becomes immediately white and friable, with a very slight calcareous cement. The lower Trenton plays the most important part in producing the marked topographical characters of the central portions of Fillmore county, since, by its superposition over the crumbling St. Peter, it constitutes the edge of the shoulder or terrace that marks their line of superposition, and not unfrequently spreads out on the top of an isolated table or mound, thinly overlain by the lower layers of the green shale, Under the head of Surface Features, this point has been mentioned already, and the reader is referred to that section.

In Fillmore county, the lower Trenton, known sometimes as the " Bluff limestone," which cor- responds in horizontality with the limestone quarried at St. Paul and Minneapolis, is much less affected by disseminated shale than in those cities, and hence makes a much more desirable building stone. The color is light blue, and in quarrying, the layers rarely exceed five inches in thickness. On weathered bluffs, the bedding appears even thinner than that, being apparently not more than two inches. When these layers are opened and considerably quarried they combine, and produce layers that are from four to six inches in thickness. They are generally tough and hard, though when broken they often fracture conchoidally, and in unexpected directions. The fossils they hold are . undergoing careful examination. The most strik- ing are species of Orthoceras, often regarded by the quarrymen as the remains of huge snakes, though really oceanic shell-fishes, and a beautiful species of Lingulepis.

The interval covered by the green shale (fifteen feet ) is not often seen well exposed. The upper- most layers have not been seen at all in Fillmore county, but the lower layers are visible in many places where the lower Trenton is quarried. When wet constantly this shale becomes a plastic clay. Along the brow of the Trenton terrace it colors the earth in nearly all roadways that cross it, and produces, by shedding the surface water, very muddy spots, in which teams are sometimes mired. One remarkable spot of this kind is near the top of the bluff a mile and a half west from Chatfield, in the southwest quarter of section one, Jordan. This shale always lies in thin layers, and sometimes embraces continuous beds of blue limestone which are exceedingly fossiliferous. It also sometimes holds fragments of limestone, of the same kind, in the form of slabs. A great many fragments of Chactetes Lycoperdon accompany this shale and roll down the face of the weathered slope, besides crinoidal fragments and species of Orthis, Leptaena and Strophomena.

The Upper Trenton, sometimes known as the Blue limestone in the northwest, which is about 125 feet thick, consists of a bluish or grayish, evenly bedded limerock, varying from fine-grained and compact, in layers of a few inches, to more vesicular, sometimes arenaceous, and in beds of one to two feet. It contains but little shale in Fillmore county-and that is near the base and near the top. This rock forms a great many pre-

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HISTORY OF FILLMORE COUNTY.

cipitous bluffs. It appears in the form of mural faces along a great many creeks and canons in the central portion of the county. It generally rises nearly perpendicularly from the top of a short talus to the summit, exhibiting a continuous sec- tion of the bedding. Its area is pre-eminently the region of "sink-holes." The canons that are so fre- quent in it run out in ascending the valleys, and disappear in a succession of "sink holes" which be- come smaller and smaller, and more and more dis- tant, till the general prairie level is reached. While in general the lithological characters of this part of the Trenton are quite uniform, near the top the layers begin to alternate with lay- ers that exhibit the characteristic lithology of the Galena, and are accompanied with some thin lay- ers of green shale. It seems to pass gradually into the Galena, or rather to assume the features that have been ascribed to that formation.

At Weisbeck's Dam, on Deer Creek, in the south . east quarter of section eleven, Spring Valley, the face of the bluff, which rises perpendicularly about a hundred feet, is wrought into a series of majestic pilasters running from the bottom to the top of the escarpment.

The weathering and erosion of the Upper Tren- ton have left many scenes of picturesque beauty in the county, some of which have been photo- graphed by Mr. Burnham, and some of them were engraved and presented in the original re- port.

Chimney rock is a crevice, originally due probably to a plane of jointage, enters the rock at a small angle with the face of the bluff, and has been widened by frost and water till it will admit a man. The detached, wedge-shaped mass, has been broken through near the foot of the bluff, and by the falling out of repeated fragments an opening, having a fanciel resemblence to an oven with a low chimney, has resulted.

The following details concerning the Trenton limestone will further elucidate this formation as it appears at various places in the county.

Southeast quarter of section twenty-three, Spring Valley, quarry of John Kleckler. The rock here is a gray limestone, with interlamina- tions of shale. This is very different from the Galena, as seen at Spring Valley village. It is compact, and, with the exception of the thin lam- inae of shale, consists entirely of limestone. Ex- posed about 10 feet.

Southeast quarter of section twenty-three,

Spring Valley, Joseph Lester has a quarry in the valley of the middle branch, very similar to Kleckler's. That of Henry Prosser occurs on the southeast quarter of section fourteen.

North part of section twenty-five, Spring Val- ley. At Mr. H. Perkins' saw-mill the same rock is visible, and has been wrought. From this point the banks of this creek become continuously rocky.

G. W. Knight's quarry is near Fillmore, section ten. The stone is hard, gray, compact, brittle, and fossiliferous, in beds of all thicknesses, de- pending on the weathering and exposure, up to eight or more inches. It is situated along the ravine, approaching Fillmore.

Geo. Shepherd's quarry is also near Fillmore, on the northeast quarter of section nine, and seems to consist mostly of isolated even layers in the shale that so frequently accompanies the Tren- ton. In this shale are Chaetetes, Rhynchonella, and Strophomena. The stone is not of much account, owing to its being encumbered so heavily with the shale, but is very desirable for the uniformity of its thickness. S. C. Pettit has a quarry of the same kind on the northeast quarter of section ten.

At Chatfield, the lower Trenton appears in the highest bluffs on the north side of the village. It is made up very largely of shale, but affords also some even layers, that are wrought. These have the same stratigraphical horizon as the stone at Minneapolis and St. Paul, but do not contain so much argillaceous matter. They are much firmer and more compact, though not so thick in the ag- gregate. Below these layers the St. Peter sand- stone is seen. The Trenton at this point has a gentle dip northeast, while the Shakopee at the mill by the river dips northwest. The brachiopod Leptaena deltoidea, so common at the Falls of St. Anthony, is here seen in great numbers, and an occasional specimen of Lingulepis quadrata. The section at the quarry of Dennis Jacob is made up of seven feet of limestone and shale, crumbling away, underlain by about eight feet of limestone.

Extensive working and burning of the upper Trenton into quicklime is carried on along Bear and Deer Creeks, the banks of which are continu- ously rocky, rising perpendicularly from one to two hundred feet from the water, in Sumner and Spring Valley township. These quarries are de- scribed under the head of Economical Geology.

Sometimes the Trenton shows, on freshly opened quarries, along the bluffs, almost a white color.

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This is particularly the case on the north half of section thirty-five, Sumner, where an opening in a long-weathered "hog's back" reveals a very light- colored limestone, in beds of about three inches, of a fine grain and compact texture; not much crystalline, and evidently impure with argilla- ceous and siliceous qualities.

The quarry of Mr. Joseph Taylor, section thir- teen, Fountain, has been mentioned already under the head of the St. Peter sandstone. and the ex- posed section given. At this quarry very large cephalopods have been taken out, and some frag- ments of Galena have been encountered, though the opening is in the lower Trenton.

The quarry of Mr. Enoch Winslow is on the same horizon as Mr. Taylor's. It is situated on the bank of Sugar Creek, in the southwest quarter of section four, Fountain. Another on the same horizon is that of John Johnson, two' miles south of Fountain. The Trenton is also wrought at Forestville and near Carimona, presenting no es- ceptional features. At Forestville it contains Receptaculites and Strophomena, and exposes a thickness of about 140 feet.

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History of Fillmore County, Including the Explorers and Pioneers of Minnesota, Part 48

Author: Edward D. Neill Publication date: 1882 Publisher: Number of Pages:

Author: Edward D. Neill
Publication date: 1882
Publisher:
Number of Pages: