Part 9

Hall, however, fell into a number of flagrant errors because of a too great reliance on lithologic correlation and supposedly similar sequence. For instance, the Coal Measures of Pennsylvania were said to directly overlap the Chemung group of southern New York, and now he finds the same condition in Ohio, Indiana, and Illinois, failing to see that in most places between the top of the New York system and the Coal Measures lay the extensive Mississippian series, one that he generally confounded with the Chemung, or included in the “Carboniferous group.” He states that the Portage of New York is the same as the Waverly of Ohio, and at Louisville the Middle Devonian waterlime is correlated with the similar rock of the New York Silurian. Hall was especially desirous of fixing the horizon of the Middle Ordovician lead-bearing rocks of Illinois, Wisconsin, and Iowa, but unfortunately correlated them with the Niagaran, while the Middle Devonian about Columbus, Ohio, and Louisville, Kentucky, he referred to the same horizon. The Galena-Niagaran error was corrected in 1855, but the Devonian and Mississippian ones remained unadjusted for a long time, and in Iowa until toward the close of the nineteenth century.

_The Geological Column of the New York Geologists of 1842–1843, according to W. W. Mather 1842._

Quaternary system │Alluvial division. „ │Quaternary division. „ │Drift division. ────────────────────────────┼────────────────────────────┬──────────── Tertiary system │These strata are included in│ │ the next lower division. │ ────────────────────────────┼────────────────────────────┼──────────── │Long Island division. Equals│New Red │ the Tertiary and │ system of Upper Secondary system │ Cretaceous marls, sands, │ Emmons and │ and clays of the coastal │ Hall. │ plain of New Jersey. │ „ │Trappean division. The │ „ │ Palisades │ „ │Red Sandstone division. │ „

Coal system of Mather, and Carboniferous system of Hall.

Old Red system of Catskill Mountains of Emmons; Catskill division of Mather and Hall; and Catskill group of Vanuxem.

_According to Hall 1843, and essentially Vanuxem 1842._

│Chemung, Portage or Nunda (divided into │ Cashaqua, Gardeau, Portage), Genesee, Erie division [Devonian] │ Tully, Hamilton (divided into │ Ludlowville; Encrinal, Moscow), and │ Marcellus. ────────────────────────────┼──────────────────────────────────────── │Corniferous, Onondaga, Schoharie, Helderberg series │ Cauda-alli, Oriskany, Upper [Devonian-Silurian] │ Pentamerus, Encrinal, Delthyris, │ Pentamerus, Waterlime, Onondaga salt │ group. ────────────────────────────┼──────────────────────────────────────── Ontario division [Silurian] │Niagara, Clinton, and Medina. ────────────────────────────┼──────────────────────────────────────── │Oneida or Shawangunk, Grey sandstone, Champlain division │ Hudson River group, Utica, Trenton, [Silurian-Ordovician-Upper│ Black River including Birdseye and Cambrian] │ Chazy, Calciferous sandrock, and │ Potsdam.

_According to Emmons 1842, Mather 1843, Vanuxem 1842, Hall 1843._

Taconic System [Ordovician │Granular quartz, Stockbridge limestone, and Lower Cambrian] │ Magnesian slate, and Taconic slate. ────────────────────────────┼──────────────────────────────────────── Primary or Hypogene system │Metamorphic and Primary rocks.

_Correlations with Europe._—The first effort toward correlating the New York system with those of Europe was made by Conrad in his Notes on American Geology in 1839 (=35=, 243). Here he compares it on faunal grounds with the Silurian system. A more sustained effort was that of Hall in 1843 (=45=, 157), when he said that the Silurian of Murchison was equal to the New York system and embraced the Cambrian, Silurian, and Devonian, which he considered as forming but one system. Hall in 1844 and Conrad earlier were erroneously regarding the Middle Devonian of New York (Hamilton) as “an equivalent of the Ludlow rocks of Mr. Murchison” (=47=, 118, 1844).

In 1846 E. P. De Verneuil spent the summer in America with a view to correlating the formations of the New York system with those of Europe. At this time he had had a wide field experience in France, Germany, and Russia, was president of the Geological Society of France, and “virtually the representative of European geology” (=2=, 153, 1846). Hall says, “No other person could have presented so clear and perfect a coup d’oeil.” De Verneuil’s results were translated by Hall and with his own comments were published in the Journal in 1848 and 1849 under the title “On the Parallelism of the Paleozoic Deposits of North America with those of Europe.” De Verneuil was especially struck with the complete development of American Paleozoic deposits and said it was the best anywhere. On the other hand, he did not agree with the detailed arrangement of the formations in the various divisions of the New York system, and Hall admitted altogether too readily that the terms were proposed “as a matter of concession, and it is to be regretted that such an artificial classification was adopted.” De Verneuil’s correlations are as follows:

The Lower Silurian system begins with the Potsdam, the analogue of the Obolus sandstone of Russia and Sweden. The Black River and Trenton hold the position of the Orthoceras limestones of Sweden and Russia, while the Utica and Lorraine are represented by the Graptolite beds of the same countries. Both correlations are in partial error. He unites the Chazy, Birdseye, and Black River in one series, and in another the Trenton, Utica, and Lorraine. Of species common to Europe and America he makes out seventeen.

In the Upper Silurian system, the Oneida and Shawangunk are taken out of the Champlain division, and, with the Medina, are referred to the Silurian, along with all of the Ontario division plus the Lower Helderberg. The Clinton is regarded as highest Caradoc or as holding a stage between that and the Wenlock. The Niagara group is held to be the exact equivalent of the Wenlock, “while the five inferior groups of the Helderberg division represent the rocks of Ludlow.” We now know that these Helderberg formations are Lower Devonian in age. De Verneuil unites in one series the Waterlime, Pentamerus, Delthyris, Encrinal, and Upper Pentamerus. Of identical species there are forty common to Europe and America.

The Devonian system De Verneuil begins, “after much hesitation,” with the Oriskany and certainly with the five upper members of Hall’s Helderberg division, all of the Erie and the Old Red Sandstone. He also adjusts Hall’s error by placing in the Devonian the Upper Cliff limestone of Ohio and Indiana, regarded by the former as Silurian. The Oriskany is correlated with the grauwackes of the Rhine, and the Onondaga or Corniferous with the lower Eifelian. Cauda-galli, Schoharie, and Onondaga are united in one series; Marcellus, Hamilton, Tully, and Genesee in another; and Portage and Chemung in a third. Of species common to Europe and America there are thirty-nine.

The Waverly of Ohio and that near Louisville, Kentucky, which Hall had called Chemung, De Verneuil correctly refers to the Carboniferous, but to this Hall does not consent. De Verneuil points out that there are thirty-one species in common between Europe and America. “And as to plants, the immense quantity of terrestrial species identical on the two sides of the Atlantic, proves that the coal was formed in the neighborhood of lands already emerged, and placed in similar physical conditions.”

An analysis of the Paleozoic fossils of Europe and America leads De Verneuil to “the conviction that identical species have lived at the same epoch in America and in Europe, that they have had nearly the same duration, and that they succeeded each other in the same order.” This he states is independent of the depth of the seas, and of “the upheavings which have affected the surface of the globe.” The species of a period begin and drop out at different levels, and toward the top of a system the whole takes on the character of the next one. “If it happens that in the two countries a certain number of systems, characterized by the same fossils, are superimposed in the same order, whatever may be, otherwise, their thickness and the number of physical groups of which they are composed, it is philosophical to consider these systems as parallel and synchronous.”

Because of the dominance of the sandstones and shales in eastern New York, De Verneuil holds that a land lay to the east. The many fucoids and ripple-marks from the Potsdam to the Portage indicated to him shallow water and nearness to a shore.

_The Oldest Geologic Eras._—We have seen in previous pages how the Primitive rocks of Arduino and of Werner had been resolved, at least in part, into the systems of the Paleozoic, but there still remained many areas of ancient rocks that could not be adjusted into the accepted scheme. One of the most extensive of these is in Canada, where the really Primitive formations, of granites, gneisses, schists, and even undetermined sediments, abound and are developed on a grander scale than elsewhere, covering more than two million square miles and overlain unconformably by the Paleozoic and later rocks. The first to call attention to them was J. I. Bigsby, a medical staff officer of the British Army, in 1821 (=3=, 254). It was, however, William E. Logan (1798–1875), the “father of Canadian geology,” who first unravelled their historical sequence. At first he also called them Primary, but after much work he perceived in them parallel structures and metamorphosed sediments, underlain by and associated with pink granites. For the oldest masses, essentially the granites, he proposed the term Laurentian system (1853, 1863) and for the altered and deformed strata, the name Huronian series (1857, 1863). Overlying these unconformably was a third series, the copper-bearing rocks. Since his day a great host of Canadian and American geologists have labored over this, the most intricate of all geology, and now we have the following tentative chronology (Schuchert and Barrell, =38=, 1, 1914):

Late Proterozoic era. Keweenawan, Animikian and Huronian periods. Early Proterozoic era. Sudburian period or older Huronian. Archeozoic era. Grenville series, etc. Cosmic history.

_The Taconic System Resurrected._

The Taconic system was first announced by Ebenezer Emmons in 1841, and clearly defined in 1842. It started the most bitter and most protracted discussion in the annals of American geology. After Emmons’s subsequent publications had put the Taconic system through three phases, Barrande of Bohemia in 1860–1863 shed a great deal of new and correct light upon it, affirming in a series of letters to Billings that the Taconic fossils are like those of his Primordial system, or what we now call the Middle Cambrian (=31=, 210, 1861, _et seq._).

In a series of articles published by S. W. Ford in the Journal between 1871 and 1886, there was developed the further new fact that in Rensselaer and Columbia counties, New York, the so-called Hudson River group abounds in “Primordial” fossils wholly unlike those of the Potsdam, and which Ford later on spoke of as belonging to “Lower Potsdam” time.

James D. Dana entered the field of the Taconic area in 1871 and demonstrated that the system also abounds in Ordovician fossiliferous formations. Then came the far-reaching work of Charles D. Walcott, beginning in 1886, which showed that all through eastern New York and into northern Vermont the Hudson River group and the Taconic system abound not only in Ordovician but also in Cambrian fossils. Finally in 1888 Dana presented a Brief History of Taconic Ideas, and laid away the system with these words (=36=, 27):

“It is almost fifty years since the Taconic system made its abrupt entrance into geological science. Notwithstanding some good points, it has been through its greater errors, long a hindrance to progress here and abroad ... But, whether the evil or the good has predominated, we may now hope, while heartily honoring Professor Emmons for his earnest geological labors and his discoveries, that Taconic ideas may be allowed to be and remain part of the past.”

As an epitaph Dana placed over the remains of the Taconic system the black-faced numerals =1841–1888=. That the remains of the system, however, and the term Taconic are still alive and demanding a rehearing is apparent to all interested stratigraphers. This is not the place to set the matter right, and all that can be done at the present time is to point out what are the things that still keep alive Emmons’s system.

In the typical area of the Taconic system, i. e., in Rensselaer County, Emmons in 1844–1846 produced the fossils _Atops trilineatus_ and _Elliptocephala asaphoides_. S. W. Ford, as stated above, later produced from the same general area many other fossils that he demonstrated to be older than the Potsdam sandstone. To this time he gave the name of Lower Potsdam, thus proving on paleontological grounds that at least some part of the Taconic system is older than the New York system, and therefore older than the Hudson River group of Ordovician age.

In 1888 Walcott presented his conclusions in regard to the sequence of the strata in the typical Taconic area and to the north and south of it. He collected Lower Cambrian fossils at more than one hundred localities “within the typical Taconic area,” and said that the thickness of his “terrane No. 5” or “Cambrian (Georgia),” now referable to the Lower Cambrian, is “14,000 feet or more.” He demonstrated that the Lower Cambrian is infolded with the Lower and Middle Ordovician, and confirmed Emmons’s statement that the former rests upon his Primary or Pre-Cambrian masses. Elsewhere, he writes: “To the west of the Taconic range the section passes down through the limestone (3) [of Lower and Middle Ordovician age] to the hydromica schists (2) [whose age may also be of early Ordovician], and thence to the great development of slates and shales with their interbedded sparry limestones, calciferous and arenaceous strata, all of which contain more or less of the Olenellus ... fauna.” He then knew thirty-five species in Washington County, New York (=35=, 401, 1888).

Finally in 1915 Walcott said that in the Cordilleran area of America there was a movement that brought about changes “in the sedimentation and succession of the faunas which serve to draw a boundary line between the Lower and Middle Cambrian series.... The length of this period of interruption must have been considerable ... and when connection with the Pacific was resumed a new fauna that had been developing in the Pacific was then introduced into the Cordilleran sea and constituted the Middle Cambrian fauna. The change in the species from the Lower to the Middle Cambrian fauna is very great.” He then goes on to show that in the Appalachian geosyncline there was another movement that shut out the Middle Cambrian _Paradoxides_ fauna of the Atlantic realm from this trough, and all deposition as well.

_Conclusions._—Accordingly it appears that everywhere in America the Lower Cambrian formations are separated by a land interval of long duration from those of Middle Cambrian time. These formations therefore unite into a natural system of rocks or a period of time. Between Middle and Upper Cambrian time, however, there appears to be a complete transition in the Cordilleran trough, binding these two series of deposits into one natural or diastrophic system. Hence the writer proposes that the Lower Cambrian of America be known as the Taconic system. The Middle and Upper Cambrian series can be continued for the present under the term Cambrian system, a term, however, that is by no means in good standing for these formations, as will be demonstrated under the discussion of the Silurian controversy.

_The Silurian Controversy._

Just as in America the base of the Paleozoic was involved in a protracted controversy, so in England the Cambrian-Silurian succession was a subject of long debate between Sedgwick and Murchison, and among the succeeding geologists of Europe. The history of the solution is so well and justly stated in the Journal by James D. Dana under the title “Sedgwick and Murchison: Cambrian and Silurian” (=39=, 167, 1890), and by Sir Archibald Geikie in his Text-book of Geology, 1903, that all that is here required is to briefly restate it and to bring the solution up to date.

Adam Sedgwick (1785–1873) and R. I. Murchison (1792–1871) each began to work in the areas of Cambria (Wales) and Siluria (England) in 1831, but the terms Cambrian and Silurian were not published until 1835. Murchison was the first to satisfactorily work out the sequence of the Silurian system because of the simpler structural and more fossiliferous condition of his area. Sedgwick, on the other hand, had his academic duties to perform at Cambridge University, and being an older and more conservative man, delayed publishing his final results, because of the further fact that his area was far more deformed and less fossiliferous. In 1834 they were working in concert in the Silurian area, and Sedgwick said: “I was so struck by the clearness of the natural sections and the perfection of his workmanship that I received, I might say, with implicit faith everything which he then taught me.... The whole ‘Silurian system’ was by its author placed _above_ the great undulating slate-rocks of South Wales.” At that time Murchison told Sedgwick that the Bala group of the latter, now known to be in the middle of the Lower Silurian, could not be brought within the limits of the Silurian system, and added, “I believe it to plunge under the true Llandeilo-flags,” now placed next below the Bala and above the Arenig, which at the present is regarded as at the base of the Ordovician.

The Silurian system was defined in print by Murchison in July, 1835, the Upper Silurian embracing the Ludlow and Wenlock, while the Lower Silurian was based on the Caradoc and Llandeilo. Murchison’s monumental work, The Silurian System, of 100 pages and many plates of fossils, appeared in 1838.

The Cambrian system was described for the first time by Sedgwick in August, 1835, but the completed work—a classic in geology—Synopsis of the Classification of the British Palæozoic Rocks, along with M’Coy’s Descriptions of British Palæozoic Fossils, did not appear until 1852–1855. Sedgwick’s original Upper Cambrian included the greater part of the chain of the Berwyns, where he said it was connected with the Llandeilo flags of the Silurian. The Middle Cambrian comprised the higher mountains of Cærnarvonshire and Merionethshire, and the Lower Cambrian was said to occupy the southwest coast of Cærnarvonshire, and to consist of chlorite and mica schists, and some serpentine and granular limestone. In 1853 it was seen that the fossiliferous Upper Cambrian included the Arenig, Llandeilo, Bala, Caradoc, Coniston, Hirnant, and Lower Llandovery. On the other hand, it was not until long after Murchison and Sedgwick passed away that the Middle and Lower Cambrian were shown to have fossils, but few of those that characterize what is now called Lower, Middle, and Upper Cambrian time.

Not until long after the original announcement of the Cambrian system did Sedgwick become aware “of the unfortunate mischief-involving fact” that the most fossiliferous portion of the Cambrian—the Upper Cambrian—and at that time the only part yielding determinable fossils, when compared with the Lower Silurian was seen to be an equivalent formation but with very different lithologic conditions. He began to see in 1842 that his Cambrian was in conflict with the Silurian system, and four years later there were serious divergencies of views between himself and Murchison. The climax of the controversy was attained in 1852, when Sedgwick was extending his Cambrian system upwards to include the Bala, Llandeilo, and Caradoc, a proceeding not unlike that of Murchison, who earlier had been extending his Silurian downward through all of the fossiliferous Cambrian to the base of the Lingula flags.

Dana in his review of the Silurian-Cambrian controversy states: “The claim of a worker to affix a name to a series of rocks first studied and defined by him cannot be disputed.” We have seen that Murchison had priority of publication in his term Silurian over Sedgwick’s Cambrian, but that in a complete presentation, both stratigraphically and faunally, the former had years of prior definition. What has even more weight is that geologists nearly everywhere had accepted Murchison’s Silurian system as founded upon the Lower and Upper Silurian formations. A nomenclature once widely accepted is almost impossible to dislodge. However, in regard to the controversy it should not be forgotten that it was only Murchison’s _Lower_ Silurian that was in conflict with Sedgwick’s _Upper_ Cambrian. As for the rest of the Cambrian, that was not involved in the controversy.

Dana goes on to state that science may accept a name, or not, according as it is, or is not, needed. In the progress of geology, he thought that the time had finally been reached when the name Cambrian was a necessity, and he included both Cambrian and Silurian in the geological record. The “Silurian,” however, included the Lower and Upper Silurian—not one system of rocks, but two.

It is now twenty-seven years since Dana came to this conclusion, at a time when it was believed that there was more or less continuous deposition not only between the formations of a system but between the systems themselves as well. To-day many geologists hold that in the course of time the oceans pulsate back and forth over the continents, and accordingly that the sequence of marine sedimentation in most places must be much broken, and to-day we know that the breaks or land intervals in the marine record are most marked between the eras, and shorter between all or at least most of the periods. Furthermore, in North America, we have learned that the breaks between the systems are most marked in the interior of the continent and less so on or toward its margins.

Hardly any one now questions the fact of a long land interval between the Lower Silurian and Upper Silurian in England, and it is to Sedgwick’s credit that he was the first to point out this fact and also the presence of an unconformity. It therefore follows that we cannot continue to use Silurian system in the sense proposed by Murchison, since it includes two distinct systems or periods. Dana, in the last edition of his Manual of Geology (1895), also recognizes two systems, but curiously he saw nothing incongruous in calling them “Lower Silurian era” and “Upper Silurian era.” It certainly is not conducive to clear thinking, however, to refer to two systems by the one name of Silurian and to speak of them individually as Lower and Upper Silurian, thus giving the impression that the two systems are but parts of one—the Silurian. Each one of the parts has its independent faunal and physical characters.