AMERICAN QUARTERLY JOURNAL

OF

AGRICULTURE AND SCIENCE.

APRIL, 1846.

AGRICULTURAL GEOLOGY OF ONONDAGA COUNTY.

In the New York system, the Onondaga rocks occupy a central position. Below them we find the whole of the inferior part of the system, which has been called the Champlain division, as well as the succeeding rock, the Medina sandstone. The same may be said of a very large proportion of the Clinton group. Those rocks which are above the Onondaga formation belong to the superior part of the Erie division, and the whole of that mass of shales and sandstones which form the Catskill mountains. The thickness of the inferior sedimentary masses below those of the county, cannot be less than three thousand feet, and those above rather exceed this estimate.

The base upon which the Onondaga formations repose, is the Medina sandstone; a rock which skirts the shore of Lake Ontario the whole distance from east to west. At the east, it is a harder rock than the west, and furnishes but a small proportion of the Vol. III., No. II.

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soil in the county of Oswego, but in Niagara its inferior portions are soft and marly, and must have contributed largely to the formation of the soil in the western and middle divisions of the state. Still, in Onondaga county, its effects are manifested rather in the furnishing an abundance of red or brown cobble stones, than the fine materials of which the soil is composed.

The Clinton group, which succeeds the Medina sandstones in the ascending order, is a heterogeneous mass of rocks, some of which are soft and shaly, and liable to disintegration; others are hard and sandy, and resist the action of the weather with considerable obstinacy. These, however, skirt the county only on its northeastern borders, passing through a portion of Lysander. The same remark, in regard to the group, which has been made of the Medina sandstone is true, that it has but little influence upon the soil of this county.

We now pass at once to the rocks of the county, and they merit, from their influence upon the agricultural capabilities of this part of New York, an extended description. We shall adopt the same divisions of the formations as those which have been given in the New York reports. 1. The red shale; 2. The greenish shale with hopper-form cavities, plaster beds and vermicular limestone layers; 3. The water limestone; 4. Onondaga limestone; 5. Marcellus shales; 6. Hamilton group.

1. Red shale. It is exceedingly soft throughout, except a few thin strata of sandstone near the top: but even these fall to pieces, and cannot be employed at all for purposes of construction. It is properly a red marl, and whenever it crops out, is generally covered by its own debris. Its greatest thickness is about 500 feet, and as it underlies the whole northern border of the county, it is agriculturally an important rock, and has contributed largely to the formation of the soil. Its debris, as would be expected from the nature of the rock, is argillaceous; but not excessively so. The nature of the soil is better indicated, however, by the composition of the rock itself: thus, the elements of one hundred grains of the most sandy part, and the same amount of softer kinds, we have found combined in the following proportions:

The sandy variety was taken from Canastota, in Madison county; the marly from Kirkville, in Onondaga county.

Observation and the result of analysis show, that this rock forms a valuable soil. It is instructive, however, to compare the composition of the soil with the rocks: thus, the soil of Canastota is composed of,

We see a great loss in carbonate of lime, and a considerable change in the other constituents. The analysis shows that the soil and rock beneath do not agree in composition, and that we cannot rely upon a supply of lime even when the rock itself is highly calcareous.

A practical observation of some value is, however, suggested by these analyses; namely, that when this red marl is favorably situated, it may be spread over the soil with advantage. It will especially have a decided effect in improving wheat lands.

We pass now to the second division of the Onondaga rocks, in the ascending order, by remarking that the red rock passes into the shales which succeed, principally by a change of color; the former becomes first green, by an increase and spread of green spots, till finally the whole mass loses its red color and is merged in an invariable dirty pea green. The whole mass is decomposable in an eminent degree, and may be distinguished by the entire absence of organic remains-by the presence of hopper-form bodies by plaster, which below is in thin beds of a columnar or fibrous structure, and above in heavy masses, which are instrumental in bending the strata, as represented in fig. 1. The

hopper-form masses are, however, found in the superior part of the formation, and even in the immediate vicinity of the layers which are quarried for hydraulic lime, as at Manlius square.

The lower mass, in which the thin plaster beds are exposed, is well exhibited at the deep cut and embankments in Camillus. At this place the rocks are exposed nearly deep enough to show the red marl. The junction, however, is rarely to be seen, in consequence of the great amount of debris and soil of the whole formation. The physical changes which it exhibits are those which appear in the successive stages from soft to hard rocks, and from imperfectly stratified beds to the thin, sharp, ringing layers of the hydraulic limestones.

The composition of the hopper-form masses is as follows:

The red marl and the green marly rock just described, when submitted to the action of cold water, furnish directly a quan tity of soluble matter: thus 100 grains yield in 6 oz. rain water:

Those rocks after they have undergone decomposition, furnish a still larger amount of saline matter, but it is composed in every instance of the same elements, among which the sulphates and chlorides are the most abundant, as shown by the following analysis:

The latter consists of chlorides of sodium and calcium, sulphates of lime and magnesia, together with a small percentage of alumina and silex.

It can hardly be expected, however, that rocks will be composed of the same elements, but all the specimens which were examined furnished soluble matter in pure rain water without