15 billion to 570 million years before present : Beginning to Ediacaran
History is the available record of past observations. Prehistory envelopes all other past occurrences. All that is known of prehistory is implied knowledge through the extrapolation of cause and effect, or more simply, common sense. A leaf seen lying on the porch implies its prehistory of growth and transport. Over time, humanity has developed many tools which aid this extrapolation, such as writing, mathematics, magnification, chemical analysis, stratigraphy, etc. Refinements in techniques are constantly occurring which alter slightly our picture of the past hopefully toward the more factual. This writing is an attempt to report what has been surmised of the prehistory of the land area now situated between latitudes 36-37 north and longitudes 94-95 west (includes the corners of southwest Missouri, northwest Arkansas, and northeast Oklahoma), as well as events which occurred in the rest of the world and universe that may have impacted this area.
Speculation and conjecture on events prior to the establishment of the form of our universe, and the will and/or natural forces instigating it, are currently beyond the scope of generally agreed upon prehistory. Therefore, we start with the theory of the Hot Big Bang. It begins with the assumption that everything in the universe was originally contained in an extremely small volume. About 13.5 billion years ago, Planck's constant, or the mathematical relation we see between matter and energy, became a physical law and force of its own. If this number were different to any degree, matter and energy would act differently. Once this relation was determined, the other physical laws and entities should appear in a logical order. First, the basic gravity of the universe becomes a necessary force, then the force which repels or separates, appears. These forces together produce heat and pressure requiring expansion. As the universe expands, pressure and temperature drop, and particles and/or waveforms, begin to form. The smallest entities - quarks, antiquarks, electrons, and other exotic particles, form first. Their production induces electromagnetism and the weak force of radioactivity to become powers. Further expansion allows protons and neutrons to form and become nuclei producing matter. Matter and energy then amass gravities of their own as they separate and clump together, and in time, produce galaxies. Universal expansion continues today at a rate of about 75 kilometers/second, and can be seen to have occurred much faster as we look into the past while sensing light which left galaxies millions and billions of years ago.
Thus, the Milky Way, our home galaxy, was probably born 10-12 billion years ago. Its early existance, while containing virtually the same mass in a much smaller volume, was probably quite spectacular. Collisions of stars, and novas igniting supernovas were likely much more common. It appears that our system was born of a nebula produced by stars which became supernova. The oldest, hands-on, chemical isotope dating has placed the time of formation of some meteorites and their contents in this pre-solar system era. The Hadean Eon, the oldest division of geologic time, began then, and the Precambrian Era encompasses all geologic time prior to the Cambrian.
Our solar system took shape 4.6 billion years ago. Initially molten, the earth slowly cooled while undergoing a dwindling bombardment over the next 600 million years. By 4.4 billion BP (Before Present), most mantle volatiles had escaped into the atmosphere which was then mainly carbon dioxide and water vapor with some methane, hydrogen sulfide, and inert gases. Free oxygen could not last long in this environment. The oldest known earth mineral crystals are zircons of Australia dated to 4.3 billion BP. The seas were forming by 4.2 billion BP. They were acidic and contained massive amounts of iron and other metals in solution.
The Archean Eon began around 4 billion BP with the beginnings of crustal formation as the extreme volcanism and incessant meteoric impacts died down. With much less heat being released from inside the earth, and a young sun producing about 70% of the energy it does now, global temperatures were probably down around that existing during the ice ages. It was under these conditions, in seas containing virtually the same amount of water as now, that complicated chemicals formed, some of which seeded their own replication, like chemical crystals. Considering the vastness and variety of nature's laboratory, it does not surprise me that nucleic acids formed, mixed, and connected, producing simple mutatable and replicable RNA molecules and eventually all the life now on earth. What amazes me is that they are the only molecules or type of molecules to have ever become a basis for life on earth.
By 3.9 billion BP, this molecular soup is thought to have developed walls, becoming individualized members of the first earth-born living kingdom, the Monera, which soon left chemical traces and metal concentrations consistent with those later known to have been produced by bacteria. Asexual reproduction by fission and a simple form of anaerobic metabolism must also have evolved by then. By 3.7 billion BP, banded iron formations began to appear which imply an oxygen generating metabolism in shallow seas as the soluble iron ions combined with the oxygen and settled out.
The earliest obvious fossils appear in sediments 3.6 billion years old. These consist of spheroid and ellipsoid single cells and filaments, and stromatolites. Stromatolites are rock formations produced as a byproduct of mats of photosynthetic blue-green algae - the Cyanophyta. Though still in existance today, their heyday ran from 3.5-2.0 billion BP, when they began to be crowded out by other organisms, including those which metabolized the oxygen that they had produced.
3.5 billion years ago, the spin of the earth had slowed enough to allow a nearly 18 hour day, and over a thousand million years of cooling had produced a surface dotted with numerous small plates separated by ocean basins with, likely, numerous small subduction areas. Some of these plates had grown enough in thickness to begin leaving evidence of tectonic activity.
Life continued to evolve, slowly due to the exact duplication of fission reproduction, but mutations did occur although far less frequently than they do with sexual reproduction. The early bacteria swarmed over the earth, filling ecologically supportive niches, and evolving into various types of single-celled creatures. Most were free-living and left few remains, but by 3.2 billion BP, the colonial stromatolite producing algae had left thick deposits in what is now North America, Greenland, Africa, and Australia, and probably existed worldwide within adaptable climates. The carbon dioxide atmosphere was slowly being reduced to oxygen and carbon, and by 3 billion BP it is thought that all major metabolic modes had evolved.
Large continents, formed by coalescence of the small plates, were raising their
Precambrian Shields by 2.8 billion BP. The Kenoran orogeny (mountain building
episode) occurred from 2.7-2.6 billion BP as the Superior-Wyoming Province of the
Canadian Shield was raised. This study is of the area on the southwest edge of the
Canadian Shield. With the raising of the shields, major stasis was met between the
lithosphere and mantle, and very little increase in continental area or volume has
occurred since then.
As the Archean Eon drew to a close, the earth enjoyed a short warming period,
bacterial production of oxygen jumped up, and the first traces of photosynthetic
bacteria on land were left. 2.5 billion BP marks the end of the Archean Eon, the
beginning of the Proterozoic Eon, as well as the beginning of the Middle Precambrian
The Proterozoic begins in an environment much altered from that existing at the
beginning of the Archean Eon. Sedimentation is now the dominant geological process,
contributed to by erosion and bacteriological processes. Atmospheric oxygen content
climbs seasonally, and the ozone layer, though still too thin for any protection, has
begun to build. Carbonate reef-like platforms are now being produced at the other
end of the life cycle. Around 2.4 billion BP, marine acidity has dropped enough to
precipitate iron compounds en masse. Throughout the world, in submerged areas,
banded iron formations appear and continue building over the next 600 million years.
Though most has been lost due to subduction, it has been estimated that they provide
90% of the world's mineable iron resources.
Glacial deposits were dropped in what is now southern Canada, south Africa,
and India 2.2 billion years ago, and it is felt that through most of the Proterozoic,
ice age conditions dominated. Average worldwide temperatures have typically
been between 12-20 degrees Centigrade with current levels around 13 degrees.
Most of the earths past since the Proterozoic has endured temperatures much
warmer, between 18 to 20 degrees. The primary control here is our distance from
the sun. The state of the gaseous envelope is secondary. A spike of 2 or 3 degrees
outside the norm has been shown to induce mass extinctions, but it must be kept
in mind that polar temperatures always ranged from extreme cold to cool temperate,
and equatorial temperatures always ranged from extreme hot to temperate.
Prokaryotic (nonnucleated) plankton were abundant 2.2 billion years ago, when the
atmosphere could first be distinguished as an oxygen atmosphere, and the ozone layer
began providing a degree of protection. Large single cells and multicellular
organisms appear around 2.1 billion BP, and Grypania, a 3/4 inch fossil probably
existed then. Mitochondria, probably acquired through the symbiosis of purple
eubacteria with early large single cells or multicellulars, began producing energy
for some aerobic organisms as part of their genetic lines. Eucaryotes, or nucleated
cells, appear around 2 billion BP, introducing the second living kingdom - the Proctista.
Early eucaryotes still reproduced by fission, simply splitting in two.
The Hudsonian orogeny of the Canadian Shield occurred around 1.8 billion years ago.
This mountain-building episode initiated the deposition of a new series of sediments
which mark the beginning of the Middle Proterozoic Period and the Late Precambrian
Period. One group of these sediments, the Keeweenawan Sequence, built between 1.8
and 1 billion BP, includes about 15,000 meters of lavas, sandstones, and shales. Also,
around 1.8 billion BP, the building of banded iron formations cease, and red beds of
oxidized iron sediments become common. 300 million years later, another orogeny of
the Canadian Shield occurred, deforming the Central Province. These Late Precambrian
orogenies probably produced the Basement Complex granites 1200-1800 feet beneath
the surface of northeast Oklahoma.
Ozarkcollenia, a stromatolyte producer, lived on volcanic tuffs in what is now the
Missouri Ozarks 1.5 billion years ago. Mitosis and meiosis and the Plant and Animal
Kingdoms were beginning to evolve, with their associates of sex, gender, and
individual lifespans. Sponge spicules have been reported from deposits of that age.
Terrestrial soil microbes appear well extablished by 1.4 billion BP, and by 1.2
billion BP, evolution had produced a wide variety of monera, plankton, seaweeds,
and numerous moranids.
One billion BP marks the beginning of the Upper Proterozoic Period. Rodinia now
exists, formed by the unification of Laurentia and Gondwanaland, the Grenville orogeny
is underway, and North America is attached to Antarctica. 900 million years ago, tiny
animals, worms, sponges, and huge probable algal organisms existed. From 800 to
around 650 million BP, it appears as though ice encircled the equator, possibly
because the earth's axis tilted further than normal. The mesoderm and coelom
evolved back then, and 750 million years ago Rodinia split into Laurasia and
675 million BP marks the end of the Proterozoic Eon, the beginning of the
Phanerozoic Eon which is still ongoing, and the beginning of the Ediacaran Period. At
this time, North America appears to have sat on the equator with South America on
its northeast side, Antarctica on its southeast side, and Australia on its southwest
side. Following the Late Proterozoic ice ages, global temperatures appear to have risen
high enough to prevent ice formation even at the poles.
Faunal assemblages from the Ediacaran Period have been located and described from
the Canadian Rockies, southwest Africa, Newfoundland, England, North Carolina,
northern Siberia, the Baikals, and Australia. Remains from this period indicate the
evolution of jellyfish, corals, conulariids, and other probable coelenterates
unaffiliated to more recent fossil forms; worms, very primitive trilobites, and
branchiopods, among many forms not yet placed on the familiar phyletic tree. Of
currently existing animal phyla, the Porifera, Annelida, Arthropoda, and Coelenterata
appear well represented. All Ediacaran fauna were low-energy, passive creatures.
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