In Georgia the older limestones are confined to the northern portion of the State, through which they are somewhat liberally distributed. They occur as marble of good quality in the counties of Gilmer, White, Cherokee, Hall, and Habersham, and in varying form in the more western counties. The most eastern development of the great Cretaceous bed of Alabama and Mississippi is found in the counties of Muscogee, Marion, and Stewart, manifesting itself as the well known rotten limestone. Immense beds of almost unaltered shells are found in central Georgia, within twenty or twenty-five miles of the gneiss and sandstone belt. The marl beds of the Tertiary in Georgia, with the foregoing exception, are similar, so far as known, to those of South Carolina, both in location and character.

FLORIDA.

The peninsula of Florida is almost everywhere underlaid with coral and shell marls of the Tertiary period, and generally consolidated. From this material a quarry on Anastasia Island, off the mouth of the St. John's River, furnishes a large supply of good building stone. Immense coast accumulations of recent shells and lime sand, formed by attrition of coral, also exist. Greensand marl has been recently reported as found in large quantity in Leon County, but no analysis has yet been obtained.

THE MARL REGION OF VIRGINIA.

From the falls of the rivers, and throughout the tide-water district, the whole country is believed to be underlaid by deposits of fossil shells, mostly near the surface, but often at considerable depths. It is these fossil beds which are commonly designated in Virginia by the general term of marl. They appear to have been formed at an era when the waters in which the animals lived were in a tranquil state; and the time they were undergoing the process of accretion must have been of incalculable duration. The tranquillity of the waters is indicated by the fact that the inclination of the beds toward the ocean is very gradual; that gregarious assemblages of the same species are frequently found imbedded together; and, above all, that many of the shells remain with the valves closed, and every part entire, as if death had ensued in a natural way; and even when separated the valves of the same shell are in close proximity.

Professor William B. Rogers made two divisions of this portion of the State. These divisions he indicated by the terms miocene and eocene, which are familiar to geologists as being applicable to different parts of the tertiary series. Under the designation of miocene are included the strata which occur in the eastern and much the larger portion of this region, in which several varieties of shell marl are procured in abundance; while the name of eocene is given to deposits of older date, existing beneath, and cropping out west of the preceding, and containing fossil shells of a different character.

According to Professor Rogers, the miocene marl district comprehends the area between the seaboard and a line conceived to be drawn through Northbury on the Pamunkey, and Coggin's Point on James River, (some six or eight miles below City Point,) in a direction nearly meridional. The eocene marl district is comprehended between the imaginary line thus described, and another line passing from the mouth of Aquia Creek, through Wales at the junction of the North and South Anna rivers, and thence through City Point. Its existence extensively beneath the miocene district was regarded by Professor Rogers as highly probable, and may now be considered certain, as a very thick deposit has been discovered by boring far down below the bed of James River, at City Point, and another at Norfolk, of great depth, in sinking an artesian well. West of City Point, however, and up to the line of granite at the falls of the river, a very good agricultural marl is found. It seems to have been deposited in estuaries of a former sea, and may be traced, at intervals, along the Petersburg and Weldon railroad, the Richmond and Petersburg road, and north of Richmond, in the same general direction, in the counties of Hanover, Caroline, and so on. In such places the beds lie near the surface, and are very accessible to farmers living along this boundary.

But it is the miocene district that is most signally favored by the richness and abundauce of the marl deposits, and their general accessibility. In the upper or western portion the country is far from being regular.

It has rather an undulating surface, with an elevation above tide of from twenty to eighty feet; and, being penetrated by several large streams, the bluffs on their margins are cut up into numerous channels. It is along these channels, high above the water-line, and along the creeks and inlets subordinate to the great rivers, and back into the interior on the same level, that marl shows itself, of the finest quality and inexhaustible in quantity. It may not, indeed, be obtained on every farm sufficiently near the surface, but few neighborhoods are without it. Such, at least, is the. case far down the rivers, until, approaching the extremities of the peninsulas, the country subsides into a vast plain, with a comparatively slight elevation above the water. Here the miocene marl disappears, which leads to the belief that it was washed away by the currents of a former sea. But the eocene strata, over which the miocene lay superimposed, still continue, though at great depths. In boring for water at Norfolk, thirty years ago, as previously referred to, shell marl was first struck at a depth of seventy feet, and there was no change in the stratum for seventy feet more, when the auger broke and the boring was discontinued.

On the eastern shore of Virginia no discovery of marl, as far as we have heard, has been made. But there are numerous banks of oyster shells-Indian banks, as they are called-on the margins of the creeks and inlets, supposed to have been accumulated by the aborigines before the discovery of the country. The shells are in a half decomposed state, and, as they readily disintegrate under the action of the plow, they are extensively used for agricultural purposes. In a district of such extent there are, as may well be supposed, several distinct varieties of marl, the most prominent of which may be described under the following classification:

1. Blue marl. This is the kind that most abounds in the upper or western part of the district. It derives its appellation from the compact blue clay in which the shells are deposited, and by a stratum of whichusually four or five feet in thickness, but destitute of fossil remains, containing only "casts "-the beds are covered. This covering has to be removed before the marl can be rendered accessible. In favorable localities, for the beds are high above the water, a natural drainage of the pits may be readily effected; but, where the ground does not admit of this, the water must be kept down by pumping. The accumulation is seldom so great, however, as to render this a laborious operation, or to interfere materially with the working of the pits. The marl is raised by a sweep or other simple machinery, or, in places where the deposits are shallow, it may be cast out on the banks by hand. When first excavated it is very heavy, and the hauling to the fields is quite laborious; but planters who are prosperous collect a large supply on the banks of the pits, enough to suffice for the operations of a whole season. In the course of a few months the moisture is drained off from the mass, and the clay also loses much of its adhesion. It is, therefore, in a better condition to be hauled on the land, while the burden of hauling is materially lightened. This variety of marl is not so rich in calcareous matter as some others, containing, perhaps, on an average, not more than fifty per cent. of carbonate of lime; but the clay which accompa nies it renders it highly useful in its application to arenaceous soils. The coloring matter of the clay is believed to be derived from the presence of minute particles of greensand, which, of itself, is a valuable ingredient in calcareous manures. The blue marl also contains crystals of gypsum, sometimes very numerous.

And here, though perhaps not strictly in place, it may be well to

describe the mode of transportation to the fields, and the usual quantity applied to the land, which is equally applicable to every variety of marl. Assuming an acre to contain, in round numbers, five thousand square yards, the field is marked off with a plow into spaces of ten yards each way, thus making fifty spaces to the acre. In the middle of each space five bushels are dropped. The boundaries being defined, it is easy to distribute with uniformity, and at any desired rate. Carts made expressly for the purpose, and of a capacity of five bushels, drawn by a single horse or mule, being provided, the work of removal goes bravely and systematically on; and with good, active drivers and sufficient teams, a large surface may be marled during periods of leisure.

This is marling at the rate of two hundred and fifty bushels to the acre, which is considered an ample dressing for any land not in a course of amelioration. On sterile lands, where there is little or no vegetation, it may be too much; and the effect would be to "marl-burn" the soil. But any land, however exhausted, may be improved by the addition of vegetable matter, such as woods litter, pine beards, &c. In places where the land has been thrown out of cultivation, and the old field pine taken possession, a large quantity of suitable material is cheaply and conveniently supplied by felling the growth, then lopping off the branches, and leaving the whole for a couple of years to decay. The marl should be previously spread over the surface that it may have the benefit of a more perfect disintegration by exposure to the air, though it may be done with nearly as good effect afterwards. In preparing for a crop, as much of the decayed vegetation should be turned in as the plow will cover. A great deal of land has, in this way, been restored from poverty to fertility.

When the shells are first taken from their beds they are in their natural shape, and possess a greater or less degree of solidity. But being mixed up with the soil by cultivation, and acted on either by the acids of the soil or the gases of the atmosphere, or both, they soon become thoroughly decomposed, and all visible trace of them is lost after a few years.

2. White marl.-In the peninsula formed by the James and the York River, and in several of the counties north of the York, are extensive beds of white, or pulverulent marl, very rich in calcareous matter; some specimens containing as much as ninety-five per cent., and generally not less than seventy-five or eighty per cent. of carbonate of lime. In these beds the shells are rarely found entire, and the condition of the fragments is such as to render it difficult to recognize the species of fossil to which they belonged. The marl presents an appearance not unlike an impure chalk. In places, however, it is mixed with a large proportion of white clay and sand, so nearly the same color as to make it difficult to distinguish between them without the application of chemical tests.

3. Greensand marl.-This abounds in the vicinity of the Pamunkey River, in the counties of Hanover and New Kent, and is perhaps the most beneficial in its action on the soil of all the varieties of fossil deposits. Besides carbonate of lime it contains potash, phosphorus, and not unfrequently ammonia. When the agriculture of Virginia was in a flourishing condition, the evidences of improvement were particularly conspicuous in that part of the State where this kind of marl is found.

4. Ferruginous marl.-In some localities the shells are deposited in a yellow or ochreous clay, which, doubtless, derives its color from the proximity of ferruginous matter. The beds in some cases are not more difficult of excavation than those of the blue marl, and the effect on the land

is very much the same. But in other localities they have become indurated and are broken up, not without considerable labor. In its texture this marl sometimes bears a resemblance to a secondary limestone, but, in the opinion of Professor Rogers, it is properly a tertiary limestone. It is found in fragmentary masses along the cliffs of York River on the southern bank, and particularly abounds in the neighborhood of Yorktown. It shows itself above the water-mark, and in precipitous places the surface has been scooped out by the action of the weather, assisted perhaps by artificial agencies. At Yorktown, for instance, there is an excavation, known by the name of Cornwallis's Cave, which tradition represents as having afforded a refuge to the commander of the British forces, at the time of the memorable siege of that place. This rock was ased to some extent in colonial times as a building material, but it has not been found to possess the requisite solidity. It contains a large percentage of carbonate of lime, and might, therefore, be converted, by burning, into a valuable agricultural lime. A specimen of the cliff at York, according to an analysis by Professor Rogers, yielded 87 per cent. of calcareous carbonate; and, computing the quantity of caustic lime corresponding to this, he estimated that a hundred pounds of the shell rock would yield 48.7 pounds of strong lime. We have no knowledge of its. having been burned, but from the abundance of fuel in the vicinity it might, without doubt, be converted into a lime useful both for agricultural and building purposes. The use of marl was seriously interrupted, not to say suspended, by the war, nor has it since been resumed to any great extent. But it is beginning now to come in request again, owing more perhaps to the increasing cultivation of peanuts than to any other cause. This crop will only come to perfection on highly calcareous soils, as otherwise the pods, however luxuriant may be the growth of vines, do not fill. According to present indication the peanut will soon become the leading crop in Eastern Virginia. From the great number of persons intending to engage in its culture during the coming season, the presumption is reasonable that the use of marl will receive a fresh stimulus, such as has not been witnessed for the last ten years.

Owing to its great weight, it has not been found profitable to transport marl beyond short distances. The white variety, being the richest and less encumbered with clay, has been lightered from one locality and even from one county to another. This was when its use first excited a general interest. Subsequently, however, it was found more economical to those who had no marl deposits on their estates to purchase what was generally known as agricultural lime, vast quantities of which came in the course of time to be taken by farmers living on the margins of the navigable streams, at whose landings it was delivered in bulk. A regular trade was kept up, for instance, between the James River and the Hudson, farmers usually paying by the cargo from seven to eight cents a bushel in its powdered state. Since the war, very little of this traffic has been going on, for which two reasons may be assigned: first, that farmers are not yet in a situation to make large investments for the progressive improvement of their estates, and second, shell lime is furnished in sufficient quantity to meet the present demand. This is supplied chiefly from Norfolk, where oyster shells accumulate in immense quantities, and is thence distributed to the inland towns, and to such interior portions of the country as are rendered accessible by lines of railway. This also goes under the general name of agricultural lime. It is the purest form in which lime can be obtained, and is sold at the kilns either by measure or weight, say twelve and a half cents a bushel