of the rock, covered by only a few inches of soil. Limerock was formerly quarried upon this island, as is testified by numerous pits, but the fractured surface stone only appears to have been removed. These fragmentary blocks seldom excee! a foot diameter, are of a white color, compact, and afford good lime. The island is but little above high water level, and the pits are now flooded.

Quarries have been opened at the lower end of Grosse Isle. The rock makes its appearance in a slightly elevated ridge, at some distance from the shore. Trenches are opened for quarrying in no place more than 5 feet deep. The upper layers are of a few inches thickness, removable in regular pieces of a size suitable for rough building. One of the trenches exposes a stratum of three feet thickness, for the distance of three hundred feet. This stratum is compact and may be broken out in nearly square

masses.

Sulphate of strontian, in large chrystals, is abundant in the upper layers. No fossils were discovered.

In section seven, of Monguagon, is a protrusion of the rock in a ridge, occupying a surface of a dozen acres. Quarries have been extensively worked, chiefly for lime. The rock is in strata of from six to ten inches thickness, of gray color, chrystalline, and eminently fossiliferous. The quarries have extended to the depth of six feet. The color of the stone deepens into blue, and its hardness increases with the depth. Calcareous spar is contained in chrystals, lining small geodes and fissures. Thin layers of indurated bituminous matter, approaching coal, are contained between some of the strata. The largest masses of stone observed to be quarried in good condition, were two feet in length by about eighteen inches wide. Whether larger slabs might rot be obtained by proper care, I was unable to learn. It is fully equal in beauty to the much admired building material brought from Ohio, but its superior hardness renders the dressing and polish much more expensive.

From nine thousand to twelve thousand bushels of lime are manufactured annually at this quarry.

Limerock makes its appearance in Brownstown creek, one and a half miles west from Gibraltar, and has been used to a very limited extent for domestic purposes.

Rock is said to appear at the water's edge on the lower end of Celeron island.

Limerock forms the rapids in the Huron at Flat Rock. It appears in a smooth, almost unbroken bed, for the distance of forty rods, forming a foundation to the dam above, and disappearing in deep water below the mills. The rock is of dark gray color, occasionally porus. A specimen contained hornstone.

Rock was also occasionally found forming the bed of the chan

nel from Flat Rock till within two miles of Mt. Pleasant, and large tabular masses, but little worn, appeared even farther up, proving the existence of rock in place at no great distance.

A very slight general dip in the limerock of this county, northwesterly, is observable.

Marl.

The only deposites of shell marl known to exist in this county in sufficient quantity for economical purposes, are in the town of Plymouth. The following deserve notice :

On section 22 (at Deacon Purdy's,) is a small deposite which occupies two-thirds of an acre. As other beds occur in the town

ship of similar origin, it may be advisable to notice the circumstances of its formation. Upon a gentle slope a protruperant bog has formed, which is wet and slightly tremulous. It consists of peat, or vegetable matter, having a depth of about three feet. Below this is found the marl, which has here a thickness of from one to three feet. It is a plastic substance of a milky gray color, perforated by roots, and may be cut out in masses like clay. The presence of lime is indicated at the surface by a calcereous deposite upon moss.

Beds thus formed originate chiefly in deposition from water of springs highly charged with lime; circumstances under which tufa, or indurated deposites of lime, usually occur. Lime is favorable to the formation of shells, which are generally associated in abundance, but do not constitute the bed as when it occupies the former bottom of a lake. Several species of the genus Helix (snails) are most numerous, with Lynnea, Planorbis, &c.

As the producing causes are still in operation, marl existing under these circumstances may be supposed still in progress of formation.

Eight hundred bushels of lime have been manufactured at this bed. Much of it beautifully white and of good quality.

The marl furnishing this number of bushels was taken from an area of three square rods. Should the deposite cover but half an acre, with the depth of a foot, (a low estimate,) the amount of lime it is capable of furnishing would be twenty-one thousand three hundred and thirty-three bushels. Five hundred bushels of the lime cost in the digging and manufacture fifty-seven days' labor. Reckoning these as so many dollars, and the lime at two shillings per bushel, (average price,) there will appear a profit of more than one half the price brought by the article.

On farm of Caleb Herrington, Esq. sections five and eight, a very extensive deposite was exposed in digging a drain to remove the water from a tamarac swamp. At several places a pole was thrust into the bed, without passing through, to the depth of six feet. From the indications apparent, I am led to believe that the

entire area of the swamp (thirty acres) is underlayed by the marl. It is compact, heavy and plastic. This marl is well adapted to the manufacture of lime, but has not yet been applied to that purpose.

On land of Sylvanus Taft, section four, is a bed of an acre or more in extent, with an average thickness of two feet. It is compact and of good quality. No lime has been manufactured, but much of it used in its natural state, by the neighbors, for plastering and whitewashing, is said to have fully answered the purposes of kiln-burnt lime.

Also on

Numerous other indications of marl occur through the township. A bed is said to exist on section twenty seven. farms of Mr. Holmes and others, probably to a small extent.

A small bed was found on land of Wm. Yerkus, section two. Upon the surface of a knoll at Waterford, a considerable quantity of a dry pulverized marl was observed.

On the farm of Pitz Taft, on the base line, within the boundary of Oakland county, is a deposite which may be noticed in this connection. It covers two acres, with an average depth of six feet. It is a tufaceous shell marl, in coarse particles, with a stratum of tufa underlying, and occurs under circumstances similar to those of the deposite on section twenty-two, first noticed.

Ten square rods have been excavated, out of which were manufactured 3,000 bushels of lime of good quality. It sells at three shillings per bushel.

Assuming the above proportion, the quantity of marl may be estimated at thirty-one thousand six hundred and eighty cubic feet. The amount of lime which the bed is capable of furnishing at ninety-six thousand bushels.

Marl, in small quantity, has also been found in town of Canton, section nine.

No experiments have been made in the employment of marl as a manure, in this county, nor, so far as I am informed, elsewhere in the state. This is somewhat a matter of surprise, since trials of plaster (gypsum) and quick lime are acknowledged to have produced extraordinary results. It is, however, scarcely known to our farmers that marl, or bog lime, may be used with equal profit while it has the advantage of being obtained at a much cheaper rate. It deserves to be made the subject of immediate and ample experiment, particularly upon sandy soils and those which are found to contain but small proportion of that essential ingredient, lime. This is often the case with the lands in the immediate vicinity of the marl beds.

Peat.

Peat, or vegetable alluvion, is found in considerable bodies in town of Plymouth, overlying the marl, and in the marshes or wet

prairies of Greenfield, Hamtramck, Ecorce, Brownstown and Huron. These latter deposites have been already noticed under the head of Marshes.

The greater proportion of peat found in th's county belongs to the variety called fibrous, being a mere mass of spongy fibres of grass roots, partially decomposed and elastic to the tread. A small proportion is of the sphagnous or peat moss variety. Comparatively little is compact, or in a state which would render it of much value for fuel.

A bed in the tamarac swamp on sections five and eight. Plymouth, to the depth of five feet, was found to consist chiefly of the kind denominated ligneous. It disclosed a half decomposed mass of tamarac logs, with moss, roots, &c. At depth of several feet, I found entire stumps, trunks and limbs of a former growth of timber, retaining their form, but so soft as to yield readily to the spade.

The body of fibrous peat which composes the marshes in Hamtramck, includes about 1,900 acres, with an average depth of four feet.

The adjoining marsh, in Greenfield and Royal Oak, comprises about 3,000 acres of this deposite, with the same average depth. Probably a portion of this peat is of ligneous origin.

From 3,000 to 4,000 acres of fibrous peat, with average depth of two feet, are contained in the marshes of West Huron.

Of the other smaller deposites of peat noticed under marshes, no estimate could be made.

None of these beds of peat have yet been esteemed of importance as an article either of fuel or manure. The wants of our population do not demand any present consideration of its value for the former purpose. But in the latter capacity, it will be found serviceable and cheap, and it is desirable that fair trials of it be made. It may not prove sufficiently decomposed for the purpose until mixed in the compost heaps and consolidated by the application of quick lime. This disposition of it might be made with peculiar facility where it occurs as in Plymouth, imposed upon beds of marl.

Bog Iron.

Deposites of bog ore occur in limited quantities at numerous places; their origin being apparent in the presence of highly ferruginous soils.

In the township of Greenfield, deposites of ore occupy a considerable extent, chiefly on sections four and nine, where I traced it at intervals over an area of one half a square mile. It follows mainly the course of two brooks discharging into a large tamarac marsh, on section ten, and embraces the intervening ash swales. It is distributed over this area in beds of a few yards

wide and irregular patches. The deposite consists of an exceedingly compact bed of a foot thickness, which is broken out in large masses, and it is mostly of inferior quality, being what is technically known as an old ore. This is succeeded by from two to six inches of the variety called shot ore, which is apparently rich. The covering of soil is from a few inches to two feet in thickness, This is by far the largest deposite in the county. Time would not permit a very accurate analysis of the ores of this county, but a more detailed account of their composition may be expected, at a future period, in treating of the other ores of the state. One hundred grains, however, subjected to a rough analysis, gave

Siliceous and aluminous matter,
Per-oxid of iron,

26,50

73,50

100,00

In township of Livonia, section twenty-eight, bog iron occurs in a low, wet swale, which serves as the outlet to a series of small marshes. The bed follows the lowest portion of the swale for about half a mile, with a width varying from two to four rods, and a thickness of six to eighteen inches. It consists mainly of a bright colored shot ore. Peaty muck overlies, of two feet ave rage depth.

Estimating the average thickness of the deposite at one foot, and its width three rods, will show a proximate result of 130,000 square feet of the ore. From the position of the low grounds following the course of the outlet, it is not improbable that other deposites of this mineral may be found below. Tue ore is a very rich one, and is well deserving a more extended investigation by the proprietor.

In township of west Huron, section twenty, is a small deposite occupying an area of thirty rods long, by one wide. It forms a compact body six to ten inches in thickness, mostly "dead ore."

On section twenty-one, a narrow deposite of bog ore occupies the bed of a small run connecting marshes. It is similar to the above, and of small extent.

Other indications of ore occur in this township; probably of but little account.

Much of the soil of the township of Plymouth is found charged with iron.

Strong indications also exist in the towns of Canton and Nankin, among the wet prairies of Ecorce and along the bottoms of the Huron, in the township of Van Buren.

Chalybeate Springs,

occur in several of the above townships.