ferns

59:4.1In the age­long strug­gle be­tween land and wa­ter, for long pe­ri­ods the sea has been com­par­a­tively vic­to­ri­ous, but times of land vic­tory are just ahead. And the con­ti­nen­tal drifts have not pro­ceeded so far but that, at times, prac­ti­cally all of the land of the world is con­nected by slen­der isth­muses and nar­row land bridges.

59:4.2As the land emerges from the last Sil­urian in­un­da­tion, an im­por­tant pe­riod in world de­vel­op­ment and life evo­lu­tion comes to an end. It is the dawn of a new age on earth. The naked and unattrac­tive land­scape of for­mer times is be­com­ing clothed with lux­u­ri­ant ver­dure, and the first mag­nif­i­cent forests will soon ap­pear.

59:4.3The ma­rine life of this age was very di­verse due to the early species seg­re­ga­tion, but later on there was free com­min­gling and as­so­ci­a­tion of all these dif­fer­ent types. The bra­chiopods early reached their cli­max, be­ing suc­ceeded by the arthro­pods, and bar­na­cles made their first ap­pear­ance. But the great­est event of all was the sud­den ap­pear­ance of the fish fam­ily. This be­came the age of fishes, that pe­riod of the world’s his­tory char­ac­ter­ized by the ver­te­brate type of an­i­mal.

59:4.4270,000,000 years ago the con­ti­nents were all above wa­ter. In mil­lions upon mil­lions of years not so much land had been above wa­ter at one time; it was one of the great­est land-emer­gence epochs in all world his­tory.

59:4.5Five mil­lion years later the land ar­eas of North and South Amer­ica, Eu­rope, Africa, north­ern Asia, and Aus­tralia were briefly in­un­dated, in North Amer­ica the sub­mer­gence at one time or an­other be­ing al­most com­plete; and the re­sult­ing lime­stone lay­ers run from 500 to 5,000 feet in thick­ness. These var­i­ous De­vo­nian seas ex­tended first in one di­rec­tion and then in an­other so that the im­mense arc­tic North Amer­i­can in­land sea found an out­let to the Pa­cific Ocean through north­ern Cal­i­for­nia.

59:4.6260,000,000 years ago, to­ward the end of this land-de­pres­sion epoch, North Amer­ica was par­tially over­spread by seas hav­ing si­mul­ta­ne­ous con­nec­tion with the Pa­cific, At­lantic, Arc­tic, and Gulf wa­ters. The de­posits of these later stages of the first De­vo­nian flood av­er­age about one thou­sand feet in thick­ness. The coral reefs char­ac­ter­iz­ing these times in­di­cate that the in­land seas were clear and shal­low. Such coral de­posits are ex­posed in the banks of the Ohio River near Louisville, Ken­tucky, and are about one hun­dred feet thick, em­brac­ing more than two hun­dred va­ri­eties. These coral for­ma­tions ex­tend through Canada and north­ern Eu­rope to the arc­tic re­gions.

59:4.7Fol­low­ing these sub­mer­gences, many of the shore lines were con­sid­er­ably el­e­vated so that the ear­lier de­posits were cov­ered by mud or shale. There is also a red sand­stone stra­tum which char­ac­ter­izes one of the De­vo­nian sed­i­men­ta­tions, and this red layer ex­tends over much of the earth’s sur­face, be­ing found in North and South Amer­ica, Eu­rope, Rus­sia, China, Africa, and Aus­tralia. Such red de­posits are sug­ges­tive of arid or semi­arid con­di­tions, but the cli­mate of this epoch was still mild and even.

59:4.8Through­out all of this pe­riod the land south­east of the Cincin­nati Is­land re­mained well above wa­ter. But very much of west­ern Eu­rope, in­clud­ing the British Isles, was sub­merged. In Wales, Ger­many, and other places in Eu­rope the De­vo­nian rocks are 20,000 feet thick.

59:4.9250,000,000 years ago wit­nessed the ap­pear­ance of the fish fam­ily, the ver­te­brates, one of the most im­por­tant steps in all pre­hu­man evo­lu­tion.

59:4.10The arthro­pods, or crus­taceans, were the an­ces­tors of the first ver­te­brates. The fore­run­ners of the fish fam­ily were two mod­i­fied arthro­pod an­ces­tors; one had a long body con­nect­ing a head and tail, while the other was a back­bone­less, jaw­less pre­fish. But these pre­lim­i­nary types were quickly de­stroyed when the fishes, the first ver­te­brates of the an­i­mal world, made their sud­den ap­pear­ance from the north.

59:4.11Many of the largest true fish be­long to this age, some of the teeth-bear­ing va­ri­eties be­ing twenty-five to thirty feet long; the pres­ent-day sharks are the sur­vivors of these an­cient fishes. The lung and ar­mored fishes reached their evo­lu­tion­ary apex, and be­fore this epoch had ended, fishes had adapted to both fresh and salt wa­ters.

59:4.12Ver­i­ta­ble bone beds of fish teeth and skele­tons may be found in the de­posits laid down to­ward the close of this pe­riod, and rich fos­sil beds are sit­u­ated along the coast of Cal­i­for­nia since many shel­tered bays of the Pa­cific Ocean ex­tended into the land of that re­gion.

59:4.13The earth was be­ing rapidly over­run by the new or­ders of land veg­e­ta­tion. Here­to­fore few plants grew on land ex­cept about the wa­ter’s edge. Now, and sud­denly, the pro­lific fern fam­ily ap­peared and quickly spread over the face of the rapidly ris­ing land in all parts of the world. Tree types, two feet thick and forty feet high, soon de­vel­oped; later on, leaves evolved, but these early va­ri­eties had only rudi­men­tary fo­liage. There were many smaller plants, but their fos­sils are not found since they were usu­ally de­stroyed by the still ear­lier ap­pear­ing bac­te­ria.

59:4.14As the land rose, North Amer­ica be­came con­nected with Eu­rope by land bridges ex­tend­ing to Green­land. And to­day Green­land holds the re­mains of these early land plants be­neath its man­tle of ice.

59:4.15240,000,000 years ago the land over parts of both Eu­rope and North and South Amer­ica be­gan to sink. This sub­si­dence marked the ap­pear­ance of the last and least ex­ten­sive of the De­vo­nian floods. The arc­tic seas again moved south­ward over much of North Amer­ica, the At­lantic in­un­dated a large part of Eu­rope and west­ern Asia, while the south­ern Pa­cific cov­ered most of In­dia. This in­un­da­tion was slow in ap­pear­ing and equally slow in re­treat­ing. The Catskill Moun­tains along the west bank of the Hud­son River are one of the largest ge­o­logic mon­u­ments of this epoch to be found on the sur­face of North Amer­ica.

59:4.16230,000,000 years ago the seas were con­tin­u­ing their re­treat. Much of North Amer­ica was above wa­ter, and great vol­canic ac­tiv­ity oc­curred in the St. Lawrence re­gion. Mount Royal, at Mon­treal, is the eroded neck of one of these vol­ca­noes. The de­posits of this en­tire epoch are well shown in the Ap­palachian Moun­tains of North Amer­ica where the Susque­hanna River has cut a val­ley ex­pos­ing these suc­ces­sive lay­ers, which at­tained a thick­ness of over 13,000 feet.

59:4.17The el­e­va­tion of the con­ti­nents pro­ceeded, and the at­mo­sphere was be­com­ing en­riched with oxy­gen. The earth was over­spread by vast forests of ferns one hun­dred feet high and by the pe­cu­liar trees of those days, silent forests; not a sound was heard, not even the rus­tle of a leaf, for such trees had no leaves.

59:4.18And thus drew to a close one of the longest pe­ri­ods of ma­rine-life evo­lu­tion, the age of fishes. This pe­riod of the world’s his­tory lasted al­most fifty mil­lion years; it has be­come known to your re­searchers as the De­vo­nian.

59:5.1The ap­pear­ance of fish dur­ing the pre­ced­ing pe­riod marks the apex of ma­rine-life evo­lu­tion. From this point on­ward the evo­lu­tion of land life be­comes in­creas­ingly im­por­tant. And this pe­riod opens with the stage al­most ide­ally set for the ap­pear­ance of the first land an­i­mals.

59:5.2220,000,000 years ago many of the con­ti­nen­tal land ar­eas, in­clud­ing most of North Amer­ica, were above wa­ter. The land was over­run by lux­u­ri­ous veg­e­ta­tion; this was in­deed the age of ferns. Car­bon diox­ide was still pres­ent in the at­mo­sphere but in less­en­ing de­gree.

59:5.3Shortly there­after the cen­tral por­tion of North Amer­ica was in­un­dated, cre­at­ing two great in­land seas. Both the At­lantic and Pa­cific coastal high­lands were sit­u­ated just be­yond the pres­ent shore lines. These two seas pres­ently united, com­min­gling their dif­fer­ent forms of life, and the union of these ma­rine fauna marked the be­gin­ning of the rapid and world-wide de­cline in ma­rine life and the open­ing of the sub­se­quent land-life pe­riod.

59:5.4210,000,000 years ago the warm-wa­ter arc­tic seas cov­ered most of North Amer­ica and Eu­rope. The south po­lar wa­ters in­un­dated South Amer­ica and Aus­tralia, while both Africa and Asia were highly el­e­vated.

59:5.5When the seas were at their height, a new evo­lu­tion­ary de­vel­op­ment sud­denly oc­curred. Abruptly, the first of the land an­i­mals ap­peared. There were nu­mer­ous species of these an­i­mals that were able to live on land or in wa­ter. These air-breath­ing am­phib­ians de­vel­oped from the arthro­pods, whose swim blad­ders had evolved into lungs.

59:5.6From the briny wa­ters of the seas there crawled out upon the land snails, scor­pi­ons, and frogs. To­day frogs still lay their eggs in wa­ter, and their young first ex­ist as lit­tle fishes, tad­poles. This pe­riod could well be known as the age of frogs.

59:5.7Very soon there­after the in­sects first ap­peared and, to­gether with spi­ders, scor­pi­ons, cock­roaches, crick­ets, and lo­custs, soon over­spread the con­ti­nents of the world. Dragon flies mea­sured thirty inches across. One thou­sand species of cock­roaches de­vel­oped, and some grew to be four inches long.

59:5.8Two groups of echin­o­derms be­came es­pe­cially well de­vel­oped, and they are in re­al­ity the guide fos­sils of this epoch. The large shell-feed­ing sharks were also highly evolved, and for more than five mil­lion years they dom­i­nated the oceans. The cli­mate was still mild and equable; the ma­rine life was lit­tle changed. Fresh-wa­ter fish were de­vel­op­ing and the trilo­bites were near­ing ex­tinc­tion. Corals were scarce, and much of the lime­stone was be­ing made by the crinoids. The finer build­ing lime­stones were laid down dur­ing this epoch.

59:5.9The wa­ters of many of the in­land seas were so heav­ily charged with lime and other min­er­als as greatly to in­ter­fere with the prog­ress and de­vel­op­ment of many ma­rine species. Even­tu­ally the seas cleared up as the re­sult of an ex­ten­sive stone de­posit, in some places con­tain­ing zinc and lead.

59:5.10The de­posits of this early Car­bonif­er­ous age are from 500 to 2,000 feet thick, con­sist­ing of sand­stone, shale, and lime­stone. The old­est strata yield the fos­sils of both land and ma­rine an­i­mals and plants, along with much gravel and basin sed­i­ments. Lit­tle work­able coal is found in these older strata. These de­po­si­tions through­out Eu­rope are very sim­i­lar to those laid down over North Amer­ica.

59:5.11To­ward the close of this epoch the land of North Amer­ica be­gan to rise. There was a short in­ter­rup­tion, and the sea re­turned to cover about half of its pre­vi­ous beds. This was a short in­un­da­tion, and most of the land was soon well above wa­ter. South Amer­ica was still con­nected with Eu­rope by way of Africa.

59:5.12This epoch wit­nessed the be­gin­ning of the Vos­ges, Black For­est, and Ural moun­tains. Stumps of other and older moun­tains are to be found all over Great Britain and Eu­rope.

59:5.13200,000,000 years ago the re­ally ac­tive stages of the Car­bonif­er­ous pe­riod be­gan. For twenty mil­lion years prior to this time the ear­lier coal de­posits were be­ing laid down, but now the more ex­ten­sive coal-for­ma­tion ac­tiv­i­ties were in pro­cess. The length of the ac­tual coal-de­po­si­tion epoch was a lit­tle over twenty-five mil­lion years.

59:5.14The land was pe­ri­od­i­cally go­ing up and down due to the shift­ing sea level oc­ca­sioned by ac­tiv­i­ties on the ocean bot­toms. This crustal un­easi­ness—the set­tling and ris­ing of the land—in con­nec­tion with the pro­lific veg­e­ta­tion of the coastal swamps, con­tributed to the pro­duc­tion of ex­ten­sive coal de­posits, which have caused this pe­riod to be known as the Car­bonif­er­ous. And the cli­mate was still mild the world over.

59:5.15The coal lay­ers al­ter­nate with shale, stone, and con­glom­er­ate. These coal beds over cen­tral and east­ern United States vary in thick­ness from forty to fifty feet. But many of these de­posits were washed away dur­ing sub­se­quent land el­e­va­tions. In some parts of North Amer­ica and Eu­rope the coal-bear­ing strata are 18,000 feet in thick­ness.

59:5.16The pres­ence of roots of trees as they grew in the clay un­der­ly­ing the pres­ent coal beds demon­strates that coal was formed ex­actly where it is now found. Coal is the wa­ter-pre­served and pres­sure-mod­i­fied re­mains of the rank veg­e­ta­tion grow­ing in the bogs and on the swamp shores of this far­away age. Coal lay­ers of­ten hold both gas and oil. Peat beds, the re­mains of past veg­etable growth, would be con­verted into a type of coal if sub­jected to proper pres­sure and heat. An­thracite has been sub­jected to more pres­sure and heat than other coal.

59:5.17In North Amer­ica the lay­ers of coal in the var­i­ous beds, which in­di­cate the num­ber of times the land fell and rose, vary from ten in Illi­nois, twenty in Penn­syl­va­nia, thirty-five in Al­abama, to sev­enty-five in Canada. Both fresh- and salt-wa­ter fos­sils are found in the coal beds.

59:5.18Through­out this epoch the moun­tains of North and South Amer­ica were ac­tive, both the An­des and the south­ern an­ces­tral Rocky Moun­tains ris­ing. The great At­lantic and Pa­cific high coastal re­gions be­gan to sink, even­tu­ally be­com­ing so eroded and sub­merged that the coast lines of both oceans with­drew to ap­prox­i­mately their pres­ent po­si­tions. The de­posits of this in­un­da­tion av­er­age about one thou­sand feet in thick­ness.

59:5.19190,000,000 years ago wit­nessed a west­ward ex­ten­sion of the North Amer­i­can Car­bonif­er­ous sea over the pres­ent Rocky Moun­tain re­gion, with an out­let to the Pa­cific Ocean through north­ern Cal­i­for­nia. Coal con­tin­ued to be laid down through­out the Amer­i­cas and Eu­rope, layer upon layer, as the coast­lands rose and fell dur­ing these ages of seashore os­cil­la­tions.

59:5.20180,000,000 years ago brought the close of the Car­bonif­er­ous pe­riod, dur­ing which coal had been formed all over the world—in Eu­rope, In­dia, China, North Africa, and the Amer­i­cas. At the close of the coal-for­ma­tion pe­riod North Amer­ica east of the Mis­sis­sippi val­ley rose, and most of this sec­tion has ever since re­mained above the sea. This land-el­e­va­tion pe­riod marks the be­gin­ning of the mod­ern moun­tains of North Amer­ica, both in the Ap­palachian re­gions and in the west. Vol­ca­noes were ac­tive in Alaska and Cal­i­for­nia and in the moun­tain-form­ing re­gions of Eu­rope and Asia. East­ern Amer­ica and west­ern Eu­rope were con­nected by the con­ti­nent of Green­land.

59:5.21Land el­e­va­tion be­gan to mod­ify the ma­rine cli­mate of the pre­ced­ing ages and to sub­sti­tute there­for the be­gin­nings of the less mild and more vari­able con­ti­nen­tal cli­mate.

59:5.22The plants of these times were spore bear­ing, and the wind was able to spread them far and wide. The trunks of the Car­bonif­er­ous trees were com­monly seven feet in di­am­e­ter and of­ten one hun­dred and twenty-five feet high. The mod­ern ferns are truly relics of these by­gone ages.

59:5.23In gen­eral, these were the epochs of de­vel­op­ment for fresh-wa­ter or­gan­isms; lit­tle change oc­curred in the pre­vi­ous ma­rine life. But the im­por­tant char­ac­ter­is­tic of this pe­riod was the sud­den ap­pear­ance of the frogs and their many cousins. The life fea­tures of the coal age were ferns and frogs.

• ferns

60:2.7The flora of this age was much like that of the pre­ced­ing. Ferns per­sisted, while conifers and pines be­came more and more like the pres­ent-day va­ri­eties. Some coal was still be­ing formed along the north­ern Med­i­ter­ra­nean shores.

• ferns

60:4.5Bi­o­log­i­cally as well as ge­o­log­i­cally this was an event­ful and ac­tive age on land and un­der wa­ter. Sea urchins in­creased while corals and crinoids de­creased. The am­monites, of pre­pon­der­ant in­flu­ence dur­ing a pre­vi­ous age, also rapidly de­clined. On land the fern forests were largely re­placed by pine and other mod­ern trees, in­clud­ing the gi­gan­tic red­woods. By the end of this pe­riod, while the pla­cen­tal mam­mal has not yet evolved, the bi­o­logic stage is fully set for the ap­pear­ance, in a sub­se­quent age, of the early an­ces­tors of the fu­ture mam­malian types.