SOILS OF THE ONONDAGA SALT-GROUP.

179

which succeed similar shales containing deposits or rounded nests of gypsum. These rest on a porous limestone, beneath which again occur green and red shales, calcareous and crumbling like those above, and like them forming rich wheat-soils. It has an average thickness of about 1200 feet, and forms a belt of generally level and undulating land, running east from Syracuse nearly a hundred miles, and west as far as Buffalo, and again beyond the Niagara River, far into Upper Canada. The breadth of this belt at Syracuse is about ten or twelve miles, and it rapidly tapers off to nothing as we go east towards the Hudson River. But westward it first expands, in Seneca and Wayne counties, to a breadth of between twenty and thirty miles, and afterwards continues from sixteen to twenty miles wide for nearly one hundred miles, after which it contracts to about twelve miles, which is its width on the river Niagara. This formation alone, therefore, forms a large area of rich land. But the country to the north of it, as far as Lake Erie, is also underlaid by rocks which crumble readily, and yield soils of good quality, and generally rich in lime; while to the south the nature of the rocks, and the agency of those causes to which the spread of drift is owing, have both in part contributed to the production of good grain-growing land. Hence, in the so-called wheatdistrict of western New York, is included the broad belt of about forty miles in width-from the shores of Lake Ontario, southwards to and including a large portion of the Hamilton shales of the New York geologists. As this country presents a really interesting illustration of the influence of geological causes on agricultural capabilities, I subjoin a section across this wheat-district at its broadest part, where it includes the eastern portion of the county of Wayne, and a portion of the county of Seneca.

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EXTENT OF THE WHEAT-REGION.

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From the lake to the beginning of the Marcellus shale -No. 6 on this section, at a height of 216 feet, the level of Seneca Lake—is about thirty miles. The rise of the country, therefore, is very gradual; indeed, it is comparatively level after the first ascent over the Niagara limestone till we reach the Marcellus shale. Beyond this shale it rises more rapidly; and at Ovid there is a bold escarpment where the two bands of limestone occur. In other parts of the country there are also bolder escarpments along the out-crop of the Niagara and Helderberg limestones than the section shows, forming marked and successive steps as we advance into the interior.

From the lake to the Marcellus shale is the proper wheat-district, though in some places it extends to the Genesee slate, and may ultimately, under a better system of culture, be generally extended thus far. But the rapid rise of the land, by altering the climate, will always make this higher region less propitious to vegetation, supposing the soil as good as those of the Onondaga and more northern formations.

No. 1. The Medina sandstone consists of layers of brownish sandstone intermixed with shales. It presents an interesting illustration of a fact of much importance in agricultural geology, that the same formation at different parts of its extent may produce soils very different in their nature. Towards the east, the sandstone greatly predominates, forming sandy soils comparatively poor in agricultural value. But towards the west, the shaley or clay beds increase in number or thickness; so that sandy loams, and finally clay loams, and excellent wheat-soils, are produced from it.

No. 2. The Clinton group consists of green and blue shales and limestones, the admixture of the fragments of which forms an excellent wheat-soil.

No. 3. The Niagara formation consists of the soft shales below, and of the thick impure limestone beds above,

182

SOILS OF THE NIAGARA ROCKS.

which give their character to the Niagara Falls, and to the outline of the landscape. The shale alone forms stiff clays, which, from the sloping nature of the surface, are generally dry and susceptible of culture; while the limestone alone, where it is sufficiently crumbled, produces a surface adapted for wheat or Indian corn. But where, from the washing away of the Clinton beds, which are only 60 or 80 feet in thickness, the Niagara shales come in contact with, or are mixed with the debris of the Medina sandstone, soils are produced which are of unequalled fertility"-illustrating another important principle, of which we have many examples in England, that, at the junction of beds of different kinds of rock, the soils are often much superior to those which are produced by the fragments of either rock alone.

No. 4. The Onondaga salt-group consists, as I have already said, of red and green shales below, succeeded by porous limestones, and these by beds of shale, including irregular but larger deposits of gypsum, the whole surmounted by other green shales or thin beds of impure light-coloured limestone, containing much magnesia. Calcareous matter abounds through the whole of this fertile formation—and generally the soils are rich, free, and easily worked.

No. 5. The Helderberg limestones and sandstones, where the surface is hard and rocky, are often covered with a thin soil of less value; but where the soil is deep, it is of excellent quality. Here, however, as a wheatregion, the natural quality of the surface begins to fall off.

No. 6. The Marcellus shale is thin, varying from a few feet to 60 or 80, so that its effect on the surface is seen chiefly by its improving the Helderberg series at the point of junction, and by forming occasional stripes and patches of stiff clay.

No. 7. The Hamilton group, when alone, forms stiff dark-coloured clays, which are less rich in calcareous

PORTAGE AND CHEMUNG SOILS.

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matter than the Onondaga soils, and therefore less free and more difficult and expensive to work, but capable of producing excellent wheat. A large portion of the celebrated Genesee Valley rests upon this formation; but its natural soil is there covered or modified by the drifted fragments of the Niagara and other more northerly limestones. This group is of great thickness, and forms an extensive belt of country, the soils of which in some places are rich in lime, and are submitted to arable culture. They are everywhere difficult to keep clean, however, and are especially infected with the pigeon-weed (Lithospermum.) They are, for the most part, therefore—like our own stiff clays of the lias and other formations-left to perpetual grass, which they produce of excellent quality. Here, therefore, the grazing and dairy country of western New York commences.

No. 8. The black Genesee slate is too thin to form an important agricultural feature in the country. It crumbles more slowly than the Hamilton shale, but where it mixes with the thin limestones and calcareous shales beneath it, good soils are produced.

No. 9. The Portage and Chemung groups consist of alternations of shales, poor in lime below, with flagstones and massive sandstones. They extend to the borders of Pennsylvania, where they reach the height of 1000 feet above Lake Ontario. The district occupied by these groups presents a complete contrast to the wheat-region. When first cleared, it produces crops of wheat; but after the first crops-as is the case in many parts of New Brunswick, which rest upon similar rocks -wheat-becomes uncertain, and spring grain only can be sown. It is therefore poorer, less cleared and cultivated, and possesses a poorer race of cultivators. The farmers devote their attention chiefly to the rearing of stock, and to the dairy husbandry.

To teach a man the close relation of natural agricul