XI.

THE "TACONIC SYSTEM," AND ITS POSITION IN STRATIGRAPHIC GEOLOGY.

DE VERNEUIL has wittily said, that "the primordial fauna of Bohemia has made a fortune; one might also say, that the Taconic fauna in America has not made a fortune"; although Barrande's conclusion on the matter is thus stated: "Simple and impartial witness of the discussions of American geologists, we recognize in the Taconic fossils the same order of succession as that which is established in the paleozoic regions of Europe."

The publication of this memoir will not cause all opposition to the "Taconic System" to cease. When we remember the favorite dogma of mud-currents and gigantic waves of water in the transportation of erratic boulders, and the lively and passionate opposition that was made to the glacial theory of Agassiz and to the ice age, we see that an opposition of forty years' standing is "hard to die." Though the dogma of the transportation of boulders by water has been again and again demolished for fifty years past, it every now and then reappears dressed up anew, as a fresh contribution to geological progress.

Two sorts of manifestations are made against the Taconic system which escape refutation by their intangible nature. One is, simply to

* See "Documents anciens et nouveaux sur la Faune primordiale et le Système Taconique en Amérique," par J. Barrande, pp. 225, 228, and 293 (Paris, 1861).

write the "so-called Taconic system," this expression containing the knowledge of the writer on the question. The other is, carefully to avoid naming the Taconic, even in the manuals destined to present to the public the actual condition of American geology.

In the same way one hears geologists say, "I do not believe in the doctrine of colonies "; or, "I do not believe in the passage of one or more species from one system of strata to another." To deny facts does not suppress them. They are there, in the field, and the only answer is, that those who do not see them are unfortunate.

"Geological theories, instead of being rigid and irrevocably fixed in their principles, should be framed with great elasticity, to embrace, if need be, unexpected facts. Geology is far from being complete for us, and is slowly forming itself, surmounting the difficulties of observation, and also painfully freeing itself from the hindrances that our limited human intelligence creates for itself by preconceived theories." *

Geology is not a science to be studied in laboratories, nor by manuals; it is by work in the field, in deciphering the manuscript that the earth spreads everywhere before us, that a knowledge of it is attained; and certain more difficult pages of this terrestrial book require many years, and often several generations of geologists, to be correctly interpreted. In the end, the truth is always victorious, in spite of opposition and obscurity, and therefore the future of the "Taconic System" is fully assured.

II. HISTORIC: 1837-1881.

1837.- The "sandstone of Potsdam" was first recognized and named by Dr. Ebenezer Emmons in 1837. In his "Second Annual Report" as Geologist of the Second Geological District of the State of New York (Albany, Feb. 15, 1838, p. 214), this name first appears, with a description of the quarries of Racket River, near Potsdam village, in the county of St. Lawrence. "Potsdam Sandstone," the designation of a group of rocks since become so celebrated in geology, was first printed on page 217 of the same Report.

1838-42.

The first appearance of the "Taconic System" is in the "Final Report on the Second District of New York" (Albany, Jan. 1, 1842), of which it constitutes Chapters VII., VIII., and IX. Dr. Ebenezer Emmons says: "A group or system of rocks which belong evidently to a position between the primary of the Atlantic

* Barrande, Défense des Colonies. IV. p. 79 (1870).

ranges of mountains and the New York system. In these remarks the writer does not expect to be able to give full justice to the subject on which he is about entering; the merit, to a certain extent, of removing some of the obscurities which envelop this system of rocks, is all that he would claim." A very modest estimate, certainly.

"The Taconic System, as its name is intended to indicate, lies along both sides of the Taconic range of mountains, whose direction is nearly north and south, or for a great distance parallel with the boundary line between the States of New York, Connecticut, Massachusetts, and Vermont. The counties through which the Taconic rocks pass are Westchester, Columbia, Rensselaer, and Washington; and after passing out of the State they are found stretching through the whole length of Vermont, and into Canada as far north as Quebec. It is, however, in Massachusetts, in the county of Berkshire, that we find the most satisfactory exhibition of these rocks. They form a belt whose width is not far from fifteen miles along the whole western border, and which extends clearly to the western part of the Taconic range."

He divides the rocks composing his Taconic system into five groups, in the following ascending order: 1. Stockbridge limestone; 2. Granular quartz; 3. Magnesian slate; 4. Sparry limestone; and 5. Taconic slate. Insisting more especially on the "liability to mistake some of the slates and limestones for those which belong to other systems." Emmons demonstrates that the Taconic system is "not connected with or related to the slates and shales of the Champlain group (Utica slate and Lorrain shales)." Finally he says: "These rocks are entirely destitute of fossils"; and "appear to be equivalent to the Lower Cambrian of Prof. Sedgwick."

In the following passage Dr. Emmons gives the exact time from which dates the Taconic system: "When, in 1836, I determined that in New York the Potsdam sandstone was the base of the Silurian system, it seemed that we had at that time the base of the sediments; but when, two years subsequently, I had observed the same base resting on sediments still older, as those along the eastern side of Champlain and elsewhere, it became evident that there was still a series older than the Silurian. The proof of this has been accumulating ever since; and the Taconic system is found to rest upon primary rocks without an exception; and it has now been observed through the whole length of the States, from N. E. to S. W. It is worthy of note,

*Geology of the Second District of New York, p. 136.

that through this whole extent the base is continuous. The most northeasterly point at which I have observed this system is at the Fox Islands, off the coast of Maine; but I have good reason to suspect its existence in Newfoundland. If so, it ranks among the most persistent geological formations of this country."

"*

1844-46. The quarto volume published in Albany, 1844, entitled, "The Taconic System, based on Observations in New York, Massachusetts, Maine, Vermont, and Rhode Island," is the work that has best made known this new system of rocks. Resuming his "Final Report" of 1842, Dr. Emmons here develops largely his first views, and extends them by explorations and observations throughout New England. The indication of fossils, all of them figured, is the most important part of the work, as follows: two Trilobites, Atops trilineatus and Elliptocephala asaphoides, found by Dr. Fitch near Bald Mountain, in Washington County, New York; several Nereites from Maine; and some Graptolites (fucoides) from the flagging-stone of Hoosick.

This memoir, except the Preface, is exactly reproduced in "Agriculture of New York," by Ebenezer Emmons, Vol. I. (Albany, 1844, 4to), with an Appendix of four pages. It constitutes the fifth chapter, from page 45 to page 112 inclusive.

1855-56. Dr. Emmons gives a new statement of the documents relating to his Taconic system in his "American Geology," Vol. I. Part II. pp. 1 to 122 (Albany, 1855, 8vc). Here are a few quotations:

"The Taconic period one of animal and vegetal life. This system is not less thoroughly peculiar in its organisms than in its physical characteristics. It is true that the number of its fossils is small when compared with the Silurian period; but, as far as they go, they stamp upon it a distinctiveness which is as marked as that of the Silurian and Çarboniferous. . . . As a general rule, however, the fossiliferous bands occupy nearly the same horizons, and they are so rarely absent that the palæontologist always expects to find them. It is not so, however, in the Taconic system; there is a general barrenness of life and vitality, which is not accounted for, unless it is regarded as due to the period in which the rocks were deposited. . . . While the Silurian carries its characteristic fossils for more than a thousand miles, the Taconic system is equally comparatively barren for the same distance. Again,

and 6.

American Geology, Part II. The Taconic System, (Albany, 1855,) pp. 5

the scarcity of fossils cannot be explained on the ground that the rocks have not been examined. This series of rocks have been under the eyes of geologists since 1817; they have been examined minutely in Rensselaer and Washington counties, New York, and Berkshire, Massachusetts, and with more or less care over the whole area of western Vermont. A few fossils only have been discovered over this large area. Of the fossils which these rocks have furnished, marine vegetables are the most common, but they are limited to a few obscure species; the thickness of the bed in which they occur is at least 2,000 feet. Graptolites rank next in numbers; they even exceed the marine plauts in the number of species which have been found. In addition to the foregoing, there are three species of Trilobites and some four or five of mollusca."

Dr. Emmons describes four marine plants, twenty-one Graptolites, six Mollusca, and three Trilobites. Of the Mollusca he says, “Most of the mollusca of this system belong to the family of Brachiopods, all of which are so minute that it is difficult to discover their most important characters." And of the Trilobites he observes, "The species, however, are unknown in the Silurian period." Finally, Emmons summarizes the Taconic system in the following manner.

"The Taconic system rests, then, on the following points: "1. Its series, divided into groups, are physically unlike the Lower Silurian series.

"2. It supports unconformably at numerous places the Lower Silurian rocks.

"3. It is a vital system, having been deposited during the period when organisms existed.

"4. As a natural history system, it is unlike the Lower Silurian; first, in containing fossils yet unknown in the Lower Silurian; and, second, in the absence of the typical forms which are prevalent in the Lower Silurian.

"5. In the Taconic system we have the paleozoic and sedimentary bases; the former comes in far above the latter, or at a long period subsequent to the time when deposits began to be formed.

"6. The Taconic system carries us back many stages farther in time, when life gave vitality to its waters, than the Silurian. It represents a period vastly longer, though it may occupy a less superficial area.” * In Chapters X., XI., and XII. of his "Geological Report of the Midland Counties of North Carolina," (Raleigh, 1856, 8vo,) Dr. Em

* American Geology, Part II. The Taconic System, p. 122.