PAPER 59
THE MARINE-LIFE ERA ON URANTIA
59:0.1 WE RECKON the history of Urantia as beginning
about one billion years ago and extending through five major eras:
59:0.2 1. The prelife era extends over the
initial four hundred and fifty million years, from about the time the planet
attained its present size to the time of life establishment. Your students
have designated this period as the Archeozoic.
59:0.3 2. The life-dawn era extends over the
next one hundred and fifty million years. This epoch intervenes between the
preceding prelife or cataclysmic age and the following period of more highly
developed marine life. This era is known to your researchers as the
Proterozoic.
59:0.4 3. The marine-life era covers the next
two hundred and fifty million years and is best known to you as the
Paleozoic.
59:0.5 4. The early land-life era extends
over the next one hundred million years and is known as the
Mesozoic.
59:0.6 5. The mammalian era occupies the last
fifty million years. This recent-times era is known as the Cenozoic.
59:0.7 The marine-life era thus covers about one
quarter of your planetary history. It may be subdivided into six long periods,
each characterized by certain well-defined developments in both the geologic
realms and the biologic domains.
59:0.8 As this era begins, the sea bottoms, the
extensive continental shelves, and the numerous shallow near-shore basins are
covered with prolific vegetation. The more simple and primitive forms of
animal life have already developed from preceding vegetable organisms, and the
early animal organisms have gradually made their way along the extensive coast
lines of the various land masses until the many inland seas are teeming with
primitive marine life. Since so few of these early organisms had shells, not
many have been preserved as fossils. Nevertheless the stage is set for the
opening chapters of that great "stone book" of the life-record preservation
which was so methodically laid down during the succeeding ages.
59:0.9 The continent of North America is wonderfully
rich in the fossil-bearing deposits of the entire marine-life era. The very
first and oldest layers are separated from the later strata of the preceding
period by extensive erosion deposits which clearly segregate these two stages
of planetary development.
1. EARLY MARINE LIFE IN THE SHALLOW SEAS
THE TRILOBITE AGE
59:1.1 By the dawn of this period of relative quiet
on the earth's surface, life is confined to the various inland seas and the
oceanic shore line; as yet no form of land organism has evolved. Primitive
marine animals are well established and are prepared for the next evolutionary
development. Ameba are typical survivors of this initial stage of animal life,
having made their appearance toward the close of the preceding transition
period.
59:1.2 400,000,000 years ago marine life,
both vegetable and animal, is fairly well distributed over the whole world.
The world climate grows slightly warmer and becomes more equable. There is a
general inundation of the seashores of the various continents, particularly of
North and South America. New oceans appear, and the older bodies of water are
greatly enlarged.
59:1.3 Vegetation now for the first time crawls out
upon the land and soon makes considerable progress in adaptation to a
nonmarine habitat.
59:1.4 Suddenly and without gradation
ancestry the first multicellular animals make their appearance. The trilobites
have evolved, and for ages they dominate the seas. From the standpoint of
marine life this is the trilobite age.
59:1.5 In the later portion of this time segment
much of North America and Europe emerged from the sea. The crust of the earth
was temporarily stabilized; mountains, or rather high elevations of land, rose
along the Atlantic and Pacific coasts, over the West Indies, and in southern
Europe. The entire Caribbean region was highly elevated.
59:1.6 390,000,000 years ago the land was
still elevated. Over parts of eastern and western America and western Europe
may be found the stone strata laid down during these times, and these are the
oldest rocks which contain trilobite fossils. There were many long fingerlike
gulfs projecting into the land masses in which were deposited these
fossil-bearing rocks.
59:1.7 Within a few million years the Pacific Ocean
began to invade the American continents. The sinking of the land was
principally due to crustal adjustment, although the lateral land spread, or
continental creep, was also a factor.
59:1.8 380,000,000 years ago Asia was
subsiding, and all other continents were experiencing a short-lived emergence.
But as this epoch progressed, the newly appearing Atlantic Ocean made
extensive inroads on all adjacent coast lines. The northern Atlantic or Arctic
seas were then connected with the southern Gulf waters. When this southern sea
entered the Appalachian trough, its waves broke upon the east against
mountains as high as the Alps, but in general the continents were
uninteresting lowlands, utterly devoid of scenic beauty.
59:1.9 The sedimentary deposits of these ages are of
four sorts:
1. Conglomerates -- matter deposited near the
shore lines.
2. Sandstones -- deposits made in shallow water
but where the waves were sufficient to prevent mud settling.
3. Shales -- deposits made in the deeper and more
quiet water.
4. Limestone -- including the deposits of
trilobite shells in deep water.
59:1.10 The trilobite fossils of these times present
certain basic uniformities coupled with certain well-marked variations. The
early animals developing from the three original life implantations were
characteristic; those appearing in the Western Hemisphere were slightly
different from those of the Eurasian group and from the Australasian or
Australian-Antarctic type.
59:1.11 370,000,000 years ago the great and
almost total submergence of North and South America occurred, followed by the
sinking of Africa and Australia. Only certain parts of North America remained
above these shallow Cambrian seas. Five million years later the seas were
retreating before the rising land. And all of these phenomena of land sinking
and land rising were undramatic, taking place slowly over millions of
years.
59:1.12 The trilobite fossil-bearing strata of this
epoch outcrop here and there throughout all the continents except in central
Asia. In many regions these rocks are horizontal, but in the mountains they
are tilted and distorted because of pressure and folding. And such pressure
has, in many places, changed the original character of these deposits.
Sandstone has been turned into quartz, shale has been changed to slate, while
limestone has been converted into marble.
59:1.13 360,000,000 years ago the land was
still rising. North and South America were well up. Western Europe and the
British Isles were emerging, except parts of Wales, which were deeply
submerged. There were no great ice sheets during these ages. The supposed
glacial deposits appearing in connection with these strata in Europe, Africa,
China, and Australia are due to isolated mountain glaciers or to the
displacement of glacial debris of later origin. The world climate was oceanic,
not continental. The southern seas were warmer then than now, and they
extended northward over North America up to the polar regions. The Gulf Stream
coursed over the central portion of North America, being deflected eastward to
bathe and warm the shores of Greenland, making that now ice-mantled continent
a veritable tropic Paradise.
59:1.14 The marine life was much alike the world
over and consisted of the seaweeds, one-celled organisms, simple sponges,
trilobites, and other crustaceans -- shrimps, crabs, and lobsters. Three
thousand varieties of brachiopods appeared at the close of this period, only
two hundred of which have survived. These animals represent a variety of early
life which has come down to the present time practically unchanged.
59:1.15 But the trilobites were the dominant living
creatures. They were sexed animals and existed in many forms; being poor
swimmers, they sluggishly floated in the water or crawled along the sea
bottoms, curling up in self-protection when attacked by their later appearing
enemies. They grew in length from two inches to one foot and developed into
four distinct groups: carnivorous, herbivorous, omnivorous, and "mud eaters."
The ability of the latter group largely to subsist on inorganic matter --
being the last multicelled animal that could -- explains their great increase
and long survival.
59:1.16 This was the biogeologic picture of Urantia
at the end of that long period of the world's history, embracing fifty million
years, designated by your geologists as the Cambrian.
2. THE FIRST CONTINENTAL FLOOD STAGE
THE INVERTEBRATE-ANIMAL AGE
59:2.1 The periodic phenomena of land elevation and
land sinking characteristic of these times were all gradual and
nonspectacular, being accompanied by little or no volcanic action. Throughout
all of these successive land elevations and depressions the Asiatic mother
continent did not fully share the history of the other land bodies. It
experienced many inundations, dipping first in one direction and then another,
more particularly in its earlier history, but it does not present the uniform
rock deposits which may be discovered on the other continents. In recent ages
Asia has been the most stable of all the land masses.
59:2.2 350,000,000 years ago saw the
beginning of the great flood period of all the continents except central Asia.
The land masses were repeatedly covered with water; only the coastal highlands
remained above these shallow but widespread oscillatory inland seas. Three
major inundations characterized this period, but before it ended, the
continents again arose, the total land emergence being fifteen per cent
greater than now exists. The Caribbean region was highly elevated. This period
is not well marked off in Europe because the land fluctuations were less,
while the volcanic action was more persistent.
59:2.3 340,000,000 years ago there occurred
another extensive land sinking except in Asia and Australia. The waters of the
world's oceans were generally commingled. This was a great limestone age, much
of its stone being laid down by lime-secreting algae.
59:2.4 A few million years later large portions of
the American continents and Europe began to emerge from the water. In the
Western Hemisphere only an arm of the Pacific Ocean remained over Mexico and
the present Rocky Mountain regions, but near the close of this epoch the
Atlantic and Pacific coasts again began to sink.
59:2.5 330,000,000 years ago marks the
beginning of a time sector of comparative quiet all over the world, with much
land again above water. The only exception to this reign of terrestrial quiet
was the eruption of the great North American volcano of eastern Kentucky, one
of the greatest single volcanic activities the world has ever known. The ashes
of this volcano covered five hundred square miles to a depth of from fifteen
to twenty feet.
59:2.6 320,000,000 years ago the third major
flood of this period occurred. The waters of this inundation covered all the
land submerged by the preceding deluge, while extending farther in many
directions all over the Americas and Europe. Eastern North America and western
Europe were from 10,000 to 15,000 feet under water.
59:2.7 310,000,000 years ago the land masses
of the world were again well up excepting the southern parts of North America.
Mexico emerged, thus creating the Gulf Sea, which has ever since maintained
its identity.
59:2.8 The life of this period continues to evolve.
The world is once again quiet and relatively peaceful; the climate remains
mild and equable; the land plants are migrating farther and farther from the
seashores. The life patterns are well developed, although few plant fossils of
these times are to be found.
59:2.9 This was the great age of individual animal
organismal evolution, though many of the basic changes, such as the transition
from plant to animal, had previously occurred. The marine fauna developed to
the point where every type of life below the vertebrate scale was represented
in the fossils of those rocks which were laid down during these times. But all
of these animals were marine organisms. No land animals had yet appeared
except a few types of worms which burrowed along the seashores, nor had the
land plants yet overspread the continents; there was still too much carbon
dioxide in the air to permit of the existence of air breathers. Primarily, all
animals except certain of the more primitive ones are directly or indirectly
dependent on plant life for their existence.
59:2.10 The trilobites were still prominent. These
little animals existed in tens of thousands of patterns and were the
predecessors of modern crustaceans. Some of the trilobites had from
twenty-five to four thousand tiny eyelets; others had aborted eyes. As this
period closed, the trilobites shared domination of the seas with several other
forms of invertebrate life. But they utterly perished during the beginning of
the next period.
59:2.11 Lime-secreting algae were widespread. There
existed thousands of species of the early ancestors of the corals. Sea worms
were abundant, and there were many varieties of jellyfish which have since
become extinct. Corals and the later types of sponges evolved. The cephalopods
were well developed, and they have survived as the modern pearly nautilus,
octopus, cuttlefish, and squid.
59:2.12 There were many varieties of shell animals,
but their shells were not then so much needed for defensive purposes as in
subsequent ages. The gastropods were present in the waters of the ancient
seas, and they included single-shelled drills, periwinkles, and snails. The
bivalve gastropods have come on down through the intervening millions of years
much as they then existed and embrace the muscles, clams, oysters, and
scallops. The valve-shelled organisms also evolved, and these brachiopods
lived in those ancient waters much as they exist today; they even had hinged,
notched, and other sorts of protective arrangements of their valves.
59:2.13 So ends the evolutionary story of the second
great period of marine life, which is known to your geologists as the
Ordovician.
3. THE SECOND GREAT FLOOD STAGE
THE CORAL PERIOD -- THE BRACHIOPOD
AGE
59:3.1 300,000,000 years ago another great
period of land submergence began. The southward and northward encroachment of
the ancient Silurian seas made ready to engulf most of Europe and North
America. The land was not elevated far above the sea so that not much
deposition occurred about the shore lines. The seas teemed with lime-shelled
life, and the falling of these shells to the sea bottom gradually built up
very thick layers of limestone. This is the first widespread limestone
deposit, and it covers practically all of Europe and North America but only
appears at the earth's surface in a few places. The thickness of this ancient
rock layer averages about one thousand feet, but many of these deposits have
since been greatly deformed by tilting, upheavals, and faulting, and many have
been changed to quartz, shale, and marble.
59:3.2 No fire rocks or lava are found in the stone
layers of this period except those of the great volcanoes of southern Europe
and eastern Maine and the lava flows of Quebec. Volcanic action was largely
past. This was the height of great water deposition; there was little or no
mountain building.
59:3.3 290,000,000 years ago the sea had
largely withdrawn from the continents, and the bottoms of the surrounding
oceans were sinking. The land masses were little changed until they were again
submerged. The early mountain movements of all the continents were beginning,
and the greatest of these crustal upheavals were the Himalayas of Asia and the
great Caledonian Mountains, extending from Ireland through Scotland and on to
Spitzbergen.
59:3.4 It is in the deposits of this age that much
of the gas, oil, zinc, and lead are found, the gas and oil being derived from
the enormous collections of vegetable and animal matter carried down at the
time of the previous land submergence, while the mineral deposits represent
the sedimentation of sluggish bodies of water. Many of the rock salt deposits
belong to this period.
59:3.5 The trilobites rapidly declined, and the
center of the stage was occupied by the larger mollusks, or cephalopods. These
animals grew to be fifteen feet long and one foot in diameter and became
masters of the seas. This species of animal appeared suddenly and
assumed dominance of sea life.
59:3.6 The great volcanic activity of this age was
in the European sector. Not in millions upon millions of years had such
violent and extensive volcanic eruptions occurred as now took place around the
Mediterranean trough and especially in the neighborhood of the British Isles.
This lava flow over the British Isles region today appears as alternate layers
of lava and rock 25,000 feet thick. These rocks were laid down by the
intermittent lava flows which spread out over a shallow sea bed, thus
interspersing the rock deposits, and all of this was subsequently elevated
high above the sea. Violent earthquakes took place in northern Europe, notably
in Scotland.
59:3.7 The oceanic climate remained mild and
uniform, and the warm seas bathed the shores of the polar lands. Brachiopod
and other marine-life fossils may be found in these deposits right up to the
North Pole. Gastropods, brachiopods, sponges, and reef-making corals continued
to increase.
59:3.8 The close of this epoch witnesses the second
advance of the Silurian seas with another commingling of the waters of the
southern and northern oceans. The cephalopods dominate marine life, while
associated forms of life progressively develop and differentiate.
59:3.9 280,000,000 years ago the continents
had largely emerged from the second Silurian inundation. The rock deposits of
this submergence are known in North America as Niagara limestone because this
is the stratum of rock over which Niagara Falls now flows. This layer of rock
extends from the eastern mountains to the Mississippi valley region but not
farther west except to the south. Several layers extend over Canada, portions
of South America, Australia, and most of Europe, the average thickness of this
Niagara series being about six hundred feet. Immediately overlying the Niagara
deposit, in many regions may be found a collection of conglomerate, shale, and
rock salt. This is the accumulation of secondary subsidences. This salt
settled in great lagoons which were alternately opened up to the sea and then
cut off so that evaporation occurred with deposition of salt along with other
matter held in solution. In some regions these rock salt beds are seventy feet
thick.
59:3.10 The climate is even and mild, and marine
fossils are laid down in the arctic regions. But by the end of this epoch the
seas are so excessively salty that little life survives.
59:3.11 Toward the close of the final Silurian
submergence there is a great increase in the echinoderms -- the stone lilies
-- as is evidenced by the crinoid limestone deposits. The trilobites have
nearly disappeared, and the mollusks continue monarchs of the seas; coral-reef
formation increases greatly. During this age, in the more favorable locations
the primitive water scorpions first evolve. Soon thereafter, and
suddenly, the true scorpions -- actual air breathers -- make their
appearance.
59:3.12 These developments terminate the third
marine-life period, covering twenty-five million years and known to your
researchers as the Silurian.
4. THE GREAT LAND-EMERGENCE STAGE
THE VEGETATIVE LAND-LIFE PERIOD
THE AGE OF FISHES
59:4.1 In 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.
59:4.2 As 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.
59:4.3 The 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.
59:4.4 270,000,000 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.
59:4.5 Five 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.
59:4.6 260,000,000 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.
59:4.7 Following 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.
59:4.8 Throughout 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.
59:4.9 250,000,000 years ago witnessed the
appearance of the fish family, the vertebrates, one of the most important
steps in all prehuman evolution.
59:4.10 The 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.
59:4.11 Many 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.
59:4.12 Veritable 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.
59:4.13 The 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.
59:4.14 As 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.
59:4.15 240,000,000 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.
59:4.16 230,000,000 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.
59:4.17 The 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.
59:4.18 And 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.
5. THE CRUSTAL-SHIFTING STAGE
THE FERN-FOREST CARBONIFEROUS PERIOD
THE AGE OF FROGS
59:5.1 The 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.
59:5.2 220,000,000 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.
59:5.3 Shortly 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.
59:5.4 210,000,000 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.
59:5.5 When 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.
59:5.6 From 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.
59:5.7 Very 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.
59:5.8 Two 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.
59:5.9 The 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.
59:5.10 The 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.
59:5.11 Toward 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.
59:5.12 This 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.
59:5.13 200,000,000 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.
59:5.14 The 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.
59:5.15 The 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.
59:5.16 The 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.
59:5.17 In 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.
59:5.18 Throughout 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.
59:5.19 190,000,000 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.
59:5.20 180,000,000 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.
59:5.21 Land 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.
59:5.22 The 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.
59:5.23 In 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.
6. THE CLIMATIC TRANSITION STAGE
THE SEED-PLANT PERIOD
THE AGE OF BIOLOGIC TRIBULATION
59:6.1 This period marks the end of pivotal
evolutionary development in marine life and the opening of the transition
period leading to the subsequent ages of land animals.
59:6.2 This age was one of great life
impoverishment. Thousands of marine species perished, and life was hardly yet
established on land. This was a time of biologic tribulation, the age when
life nearly vanished from the face of the earth and from the depths of the
oceans. Toward the close of the long marine-life era there were more than one
hundred thousand species of living things on earth. At the close of this
period of transition less than five hundred had survived.
59:6.3 The peculiarities of this new period were not
due so much to the cooling of the earth's crust or to the long absence of
volcanic action as to an unusual combination of commonplace and pre-existing
influences -- restrictions of the seas and increasing elevation of enormous
land masses. The mild marine climate of former times was disappearing, and the
harsher continental type of weather was fast developing.
59:6.4 170,000,000 years ago great
evolutionary changes and adjustments were taking place over the entire face of
the earth. Land was rising all over the world as the ocean beds were sinking.
Isolated mountain ridges appeared. The eastern part of North America was high
above the sea; the west was slowly rising. The continents were covered by
great and small salt lakes and numerous inland seas which were connected with
the oceans by narrow straits. The strata of this transition period vary in
thickness from 1,000 to 7,000 feet.
59:6.5 The earth's crust folded extensively during
these land elevations. This was a time of continental emergence except for the
disappearance of certain land bridges, including the continents which had so
long connected South America with Africa and North America with
Europe.
59:6.6 Gradually the inland lakes and seas were
drying up all over the world. Isolated mountain and regional glaciers began to
appear, especially over the Southern Hemisphere, and in many regions the
glacial deposit of these local ice formations may be found even among some of
the upper and later coal deposits. Two new climatic factors appeared --
glaciation and aridity. Many of the earth's higher regions had become arid and
barren.
59:6.7 Throughout these times of climatic change,
great variations also occurred in the land plants. The seed plants
first appeared, and they afforded a better food supply for the subsequently
increased land-animal life. The insects underwent a radical change. The
resting stages evolved to meet the demands of suspended animation
during winter and drought.
59:6.8 Among the land animals the frogs reached
their climax in the preceding age and rapidly declined, but they survived
because they could long live even in the drying-up pools and ponds of these
far-distant and extremely trying times. During this declining frog age, in
Africa, the first step in the evolution of the frog into the reptile occurred.
And since the land masses were still connected, this prereptilian creature, an
air breather, spread over all the world. By this time the atmosphere had been
so changed that it served admirably to support animal respiration. It was soon
after the arrival of these prereptilian frogs that North America was
temporarily isolated, cut off from Europe, Asia, and South America.
59:6.9 The gradual cooling of the ocean waters
contributed much to the destruction of oceanic life. The marine animals of
those ages took temporary refuge in three favorable retreats: the present Gulf
of Mexico region, the Ganges Bay of India, and the Sicilian Bay of the
Mediterranean basin. And it was from these three regions that the new marine
species, born to adversity, later went forth to replenish the seas.
59:6.10 160,000,000 years ago the land was
largely covered with vegetation adapted to support land-animal life, and the
atmosphere had become ideal for animal respiration. Thus ends the period of
marine-life curtailment and those testing times of biologic adversity which
eliminated all forms of life except such as had survival value, and which were
therefore entitled to function as the ancestors of the more rapidly developing
and highly differentiated life of the ensuing ages of planetary
evolution.
59:6.11 The ending of this period of biologic
tribulation, known to your students as the Permian, also marks the end
of the long Paleozoic era, which covers one quarter of the planetary
history, two hundred and fifty million years.
59:6.12 The vast oceanic nursery of life on Urantia
has served its purpose. During the long ages when the land was unsuited to
support life, before the atmosphere contained sufficient oxygen to sustain the
higher land animals, the sea mothered and nurtured the early life of the
realm. Now the biologic importance of the sea progressively diminishes as the
second stage of evolution begins to unfold on the land.
Presented
by a Life Carrier of Nebadon, one of the original corps assigned to
Urantia.
