been made up to this time upon the geology of any part of the State. The descriptions and figures of fossils in this paper were made by Samuel George Morton, M. D., of Philadelphia.

It was in this year also that the first steps were taken by the legislature to determine the geological structure and resources of the State. A resolution was passed on the 14th day of March, 1836, providing for the appointment of a committee to report to the next legislature the best method of obtaining a complete geological survey of the State and the probable cost of the same. The committee consisted of Dr. S. P. Hildreth, chairman, Professors John Locke and J. H. Riddell and Mr. I. A. Lapham, all of whom were recognized as among the foremost students of geological science in the State.

The report of this committee was promptly made and, in accordance with its recommendations, a survey of the State was forthwith ordered (March 27, 1837). The first geological corps was organized as follows:

Prof. W. W. Mather, State Geologist.
Dr. S. P. Hildreth.

Dr. John Locke.

Prof. J. P. Kirtland.
Col. J. W. Foster.
Col. Chas. Whittlesley.
Prof. C. Briggs, Jr.

The work of this survey was brought to an
abrupt termination at the end of the second
year of field work, the principal cause of dis-
continuance being the embarrassed condition
of the State treasury, which in turn was owing
to the financial panic of 1837. Though the
duration of this survey was short, its results
were of very great importance and value. A
solid foundation had been laid on which ob-
servations could be intelligently carried on in
every portion of the State. Several of the
members of the old corps, and prominent
among them, Col. Charles Whittlesley, main-
tained not only their interest, but their field
work as well, though in a fragmentary and
disconnected way, and from year to year work
was done which could finally be utilized in a
more thorough study of the subject.
owe very much to the members of this corps
for their contributions to our knowledge of
Ohio geology.

We

The second survey was ordered by the legis lature in 1869, and there was fortunately placed at the head of it Professor J. S. Newberry, LL. D., widely recognized as the ablest geologist that Ohio has yet produced. Dr. Newberry brought to his task the results of many years of study of the structure of Ohio and also a wide experience in other fields. To his sagacity in interpreting both the stratigraphical and paleontological record of the State, science is under great obligations. The assistant geologists appointed with Dr. Newberry were Prof. E. B. Andrews, Prof. Edward Orton and Mr. J. H. Klippart Prof. T. G. Wormley was appointed chemist of the survey. Active work

on the survey was discontinued at the end of five years from the date of beginning, but the publication of results was kept up for a much longer time. In fact, some of the results of Dr. Newberry's work are yet unpublished. Two reports of progress, 1869 and 1870, and four volumes of Geology are the published results of this survey. Two of these volumes are double, the second parts being devoted to paleontology (Vols. I. and II.).

In 1881 the survey was again revived, under the direction of Prof. Edward Orton, with special reference to the completion of the work in economic geology. Two volumes, viz., vols. V. and VI., have been already issued in this series. Prof. N. W. Lord was appointed chemist to the survey under the reorganization, and has done all of the work in this important department.

I. GEOLOGICAL SCALE.

A brief review of the scale and structure of the State will here be given, but before it is entered upon, a few fundamental facts pertaining to the subject will be stated.

1. So far as its exposed rock series is concerned, Ohio is built throughout its whole extent of stratified deposits or, in other words, of beds of clay, sand and limestone, in all their various gradations, that were deposited or that grew in water. There are in the Ohio series no igneous nor metamorphic rocks whatever; that is, no rocks that have assumed their present form and condition from a molten state or that, subsequent to their original formation. have been transformed by heat. The only qualification which this statement needs pertains to the beds of drift by which a large portion of the State is covered. These drift beds contain bowlders in large amount, derived from the igneous and metamorphic rocks that are found around the shores of Lakes Superior and Huron, but these bowlders are recognized by all, even by the least observant, as foreign to the Ohio scale. They are familiarly known as “lost rocks" or erratics.

If we should descend deep enough below the surface we should exhaust these stratified deposits and come to the granite foundations of the continent which constitute the surface rocks in parts of Canada, New England and the West, but the drill has never yet hewed its way down to these firm and massive beds within our boundaries.

The rocks that constitute the present surface of Ohio were all formed in water, and none of them have been modified and masked by the action of high temperatures. They remain in substantially the same condition in which they were formed.

2. With the exception of the coal seams and a few beds associated with them and of the drift deposits, all the formations of Ohio grew in the sea. There are no lake or river deposits among them, but by countless and infallible signs they testify to a marine origin. The remnants of life which they contain, often in the greatest abundance, are decisive as to this point.

3. The sea in which or around which they grew was the former extension of the Gulf of Mexico. When the rocks of Ohio were in process of formation, the warm waters and genial climate of the Gulf extended without interruption to the borders of the great lakes. All of these rocks had their origin under such conditions.

4. The rocks of Ohio constitute an orderly series. They occur in widespread sheets, the lowermost of which are co-extensive with the limits of the State. As we ascend in the scale, the strata constantly occupy smaller areas, but the last series of deposits, viz., those of the Carboniferous period, are still found to cover at least one-fourth of the entire area of the State. Some of these formations can be followed into and across adjacent States, in apparently unbroken continuity.

The edges of the successive deposits in the Ohio series are exposed in innumerable natural sections, so that their true order can generally be determined with certainty and ease.

5. For the accumulation and growth of this great series of deposits, vast periods of time are required. Many millions of years must be used in any rational explanation of their origin and history. All of the stages of this history have practically unlimited amounts of past time upon which to draw. They have all gone forward on so large a scale, so far as time is concerned, that the few thousand years of human history would not make an appreciable factor in any of them. In other words, five thousand years or ten thousand years make too small a period to be counted in the formation of coal, for example, or in the accumulation of petroleum, or in the shaping of the surface of the State through the agencies of erosion.

The geological scale of the State is represented in the accompanying diagram (page 6). The order of the series is, of course, fixed aud definite, but the thickness assigned to the several elements depends upon the location at which the section is taken. The aggregate thickness of the entire series will reach 5,000 feet, if the maximum of each stratum is taken into the account, but if the average measurements are used, the thickness does not exceed 3,500 feet. The principal elements of the scale, which extends from the Lower Silurian to the upper Carboniferous or possibly the Permian, inclusive, are given below, and the geological map appended shows how the surface of the State is distributed among the principal formations. brief review of these leading elements will be given at this point.

1. THE TRENTON LIMESTONE.

A

The Trenton limestone is one of the most important of the older formations of the continent. It is the first widespread limestone of the general scale. It extends from New England to the Rocky mountains, and from the islands north of Hudson's bay to the southern extremity of the Allegheny mountains in Alabama and Tennessee.

Throughout this vast region it is found exposed in innumerable outcrops. It gives rise as it decays to limestone soils which are some times of remarkable fertility, as, for example, those of the famous Blue Grass region of Central Kentucky, which are derived from it. It is worked for building stone in hundred of quarries, and it is also burned into lime and broken into road metal on a large scale throughout the regions where it occurs. But widespread as are its exposures in outcrop, it has a still wider extension under Cover. It is known to make the floor of entire States in which it does not reach the surface at a single point.

It takes its name from a picturesque and well-known locality in Trenton township. Oneida county, New York. The West Canada creek makes a rapid descent in this township from the Adirondack uplands to the Mohawk valley, falling 300 feet in two miles by a series of cascades. These cascades have long been known as Trenton Falls, and the limestone which forms them was appropriately named by the New York geologists the Trenton limestone. The formation, as seen at the original locality, is found to be a dark-blue, almost black limestone, lying in quite massive and even beds, which are often separated by layers of black shale. Both limestone and shale contain excellently preserved fossils of Lower Silurian age. By means of these fossils, and also by its stratigraphical order, the limestone is followed with perfect distinctness from Trenton Falls to every point of the compass. It is changed to some extent, in color and composition, as it is traced in different directions, but there is seldom a question possible as to its identity. The Trenton limestone forms several of the largest islands in whole or in part in the northern portion of Lake Huron, as the Manitoulin islands and Drummond's island. It dips from this region to the southward, but it is found rising again in outcrop in the valley of the Kentucky river. Its presence underneath the entire States of Ohio and Michigan, and especially under Western Ohio, has always been inferred, since the geology of these States was first worked out. But it is only recently that it has come to be clearly recognized as one of the surface formations of Ohio.

The lowest rocks in the State series have long been known to be exposed in the Point Pleasant quarries of Clermont county. It is upon the outcrop of these rocks that the humble dwelling stands in which Ulysses S. Grant first saw the light. The claim that these beds in reality belong to and represent the Trenton limestone of Kentucky was first made by S. A. Miller, Esq., of Cincinnati, and the same view was afterward supported by the late Wm. M. Linney of the Kentucky Geological Survey, but the demonstration of the fact comes in an unexpected way. In the extensive underground explorations that have been going forward in Northern Ohio for the last few years, the Trenton limestone has been unmistakably ident:fied as the firm