300 



GEOLOGY IN AMERICA. 



[1855. 



the Onondarja, tlio Lower Ileldcrherg, and many subordinate epochs- 

 each one characterized by its jjecnliar organic remains; each evidence 

 of the nearly or qnito universal devastation that preceded it, and of the 

 act of omnipotence that re-instated life on the globe ; each, too, bear- 

 in" evidence of shallow or only moderately deep waters when they were 

 formed ; and the Onondaga period — the period of the New York salt 

 rocks telling of a half emerged continent of considerable extent. 



Another devastation took place, and then opened, as De Verneuil 

 has shown, the Devonian Age, or Age of Fishes. It commenced, like 

 the Upper Silurian, with coarse sandstones, evidence of a time of vio- 

 lence ; these were followed by another grit-rock, whose few organic 

 remains show that life had already re-appeared. Then another change 



a change evidently in depth of water — and limestones were forming 



over the continent, from the Hudson far westward ; the whole surface 

 became an exuberant coral-reef, far exceeding in extent, if not in bril- 

 liancy, any modern coral sea ; for such was a portion, at least, of the 

 Upper Helderberg period. 



Again, there was a general devastation, leaving not a trace of the 

 former life in the wide seas ; and where were coral reefs, especially in 

 the more eastern portion of the continental seas, sandstones, and shales 

 accumulated for thousands of feet in thickness, with rarely a thin layer 

 of limestone. Thus passed the Hamilton, Chenmnr;, and CatlskiU 

 Periods of the Devonian Age. The life of these regions, which in some 

 epochs was exceedingly profuse, was three or four times destroyed and 

 renewed, not renewed by a re-creation of the same species, but of 

 others ; and although mostly like the earlier ya genera, yet each hav- 

 ing characteristic marks of the period to which it belonged. And while 

 these Devonian periods were passing, the first land plants appeared, 

 foretellers of the age of verdure next to follow. 



Then come vast beds of conglomerate, a natural opening of a new 

 chapter in the record; and here it is convenient to place the beginning 

 of the Carboniferous, or the Age of Acrogens. Sandstone and shales 

 succeeded reaching a thickness in New Jersey and Pennsylvania, ac- 

 cording to Professor Rogers, of thousands of feet ; while in the basin 

 of the Ohio and Mississippi, in the course of this era, the carbonifer- 

 ous limestone was forming immense Crinoidal plantations in the seas. 



Another extermination took place of all the beautiful life of the wat- 

 ers, and a conglomerate or sandstone was spread over the encrinital 

 bed ; and this introduced the true Coal period of the Carboniferous 

 A^e ; for it ended in leaving the continent, which had been in long 

 continued oscillations, quite emerged. Over the regions where encri- 

 nites were blooming, stretch our vast prairies or wet meadows of the 

 luxuriant coal vegetation. The old system of oscillation of the surface 

 still continues, and many times the continent sinks to rise again — in 

 the sinking extinguishing all continental life, and exposing the surface 

 to new depositions of sandstone, clays, or limestone, over the accumu- 

 lated vegetable remains ; in the rise depopulating the seas by drying 

 them up, and preparing the soil for verdure again ; or at times convul- 

 sive movements of the crust carry the seas over the land, leaving de- 

 struction behind. Thus by repeated alternations the coal period passes 



some 6000 feet of rock and coal beds being foi-med in Pennsylvania, 



and 14,000 feet in Nova Scotia. 



• I have passed on in rapid review, in order to draw attention to the 

 series or succession of chauges, instead of details. So brief an outline 

 may lead a mind not familiar with the subject to regard the elapsed 

 time as short, whereas, to one who follows the various alternations and 

 the whole order of events, the idea of time immeasurable becomes almost 

 oppressive. 



Before continuing the review I will mention some conclusions which 

 are here suggested : 



1. In the "first place, through the periods of the Silurian and De- 

 vonian, at twelve distinct epochs at least, the seas on this American 

 Continent were swept of nearly all existing life, and as many times it 

 was repeopled, and this is independent of many partial exterminations 

 and renewals of life that at other times occurred. 



If omnipotent power had been limited to making monads for after 

 development into higher forms, many a time would the whole process 

 have been utterly frustrated by hot water, or by mere changes of level 

 in the earth's crust, and creation would have been at the mercy of 

 dead forces. The surface would have required again and again the 

 sowing of monads, and there would have been a total failure of crops 

 after all ; for these exterminations continue to occur through all geo- 

 logical time into the Mammalian Age. 



2. Again, I have observed that the Continent of North America has 

 never been the deep ocean's bed, but a region of comparatively shal- 

 low seas, and at times emerging land, and was marked out in its great 

 outlines even in the earliest Silurian. The same view is urged bv Do 



Verneuil, and appears now to bo the prevailing opinion among Ameri- 

 can geologists. The depth at times may have been measured by the 

 thousand feet, but not by miles. 



3. During the first half of the Lower Silurian Era, the whole East 

 and West were alike in. being covered by the sea. In the first or Pots- 

 dam period, the Continent was just beneath its surface. In the next, 

 or Trenton period, the depth was greater, giving purer waters for 

 abundant marine life. Afterwards the east and west were in general 

 widely diverse in their formations ; limestones, as Mr. Hall and the 

 Profs. Rogers have remarked, were in progress over the west ; that 

 is, the region now the great Mississippi Valley, beyond the Appala- 

 chians ; while sandstones and shales were forming through north- 

 eastern New York, south and south-west through Virginia. The 

 former, therefore, has been regarded as an area of deeper water ; the 

 latter as in general shallow, when not actually emerged. In fact, the 

 region toward the Atlantic border, afterward raised into the Appala- 

 chians, was already, even before the Lower Silurian Era closed, the 

 higher part of the land ; it lay as a great reef, or sand bank, partly 

 hemming in a vast continental lagoon, where corals, encrinitea and 

 molluscs grew in profusion ; thus partly separating the already ex- 

 isting Atlantic from the interior waters. 



The oscillations or changes of level over the continent through the 

 Upper Silurian and Devonian had some reference to this border re- 

 gion of the continent ; the formations approach or recede from it, and 

 sometimes pass it, according to the limits of the oscillations eastward 

 or westward. Along the course of the border itself, there were deep 

 subsidences in slow progress, as is shown by the thickness of the beds. 

 It would require much detail to illustrate these points, and I leave 

 them with this bare mention. 



The Hudson River and Champlain valleys appear to have had their 

 incipient origin at the epoch that closes the Lower Silurian ; for while 

 the preceding formations cross this region, and continue over New 

 England, the rocks of the Niagara and Onondaga periods (the first two 

 of the Upper Silurian) thin out in New York before reaching the Hud- 

 son River. Mr. Logan has recognized the division of America to the 

 north-east into two basins, by an anticlinal axis along Lake Cham- 

 plain, and observes also that the disturbances began as early at least 

 as the close of the Lower Silurian, mentioning, too, that there is actu- 

 ally a want of conformity in Gaspfe between the beds of the Upper and 

 Lower Silurian — another proof of the violence that closed the Lower 

 Silurian era. 



But let us pass onward in our geological review. All the various 

 oscillations that were in slow movement through the Silurian, De- 

 vonian and Carboniferous ages, and which were increasing theii' fre- 

 quency throughout the last, raising and dipping the layers in many 

 alternations, were premonitions of the great period of revolution, so 

 well elucidated, as already observed, by the Professors Rogers, when 

 the Atlantic border, from Labrador to Alabama, long in preparation, 

 was at last folded up into mountains, and the Silurian, Devonian and 

 Carboniferous rocks were baked and crystallized. No such event had 

 happened since the revolution closing the Azoic period. From that 

 time on, all the various beds of succeeding ages, up to the top of the 

 Carboniferous, had been laid down in horizontal or nearly horizontal 

 layers — over New England as well as in the West ; for the continent 

 from New England westward, we have reason to believe, was then 

 nearly a plain either above or below the water ; there had been no 

 disturbances except minor uplifts ; the deposits with small exceptions 

 were a single unbroken record, until this Appalachian revolution. 



This epoch, although a time of vast disturbances, is more correctly 

 contemplated as an epoch of the slow-measured movement of an 

 agency of inconceivable power, pressing forward from the ocean to- 

 ward the north-west ; for the rocks were folded up without the cha- 

 otic destruction that sudden violence would have been likely to pro- 

 duce. Its greatest force and its earliest beginning was to the north- 

 north-east. I have alluded to the disturbances between the Upper 

 and Lower Silurian beds of Gaspfe to the North. Another epoch of 

 disturbance, still more marked, preceded (according to Mr. Logan) 

 the carboniferous beds in those north-eastern regions ; and New 

 England, while a witness to the profound character and thoroughness 

 of the Appalachian revolution, attests also to the greater distrrrbance 

 toward its north-eastern limits. Some of the carboniferous strata 

 were laid down here in Rhode Island, as clay and sand, and layers of 

 vegetable debris ; they came forth from the Appalachianflres as you 

 have them, the beds contorted, the coal layers a hard silicious anthra- 

 cite or even graphite in places, the argillacous sands and clays, crys- 

 tallized into talcose, or even gneiss and syenite. 



These very coal beds, so involved in the crystalline rocks, are part 



