In part three of this series, Christopher F. Ash argued the sea level changes produced a superior distribution of fertile silts over the Ice Age lowland plains -- later lost to the early Holocene floods. In part four, Christopher presents his central thesis: that the ocean itself, during flood periods, transformed the coastal soils into the most fertile the world has ever known.
Part 4: Nature's Fertilizer
The next day the army traveled over a desert plain where DeSoto's servant reportedly "died" of thirstthere are no lakes, springs, sinkholes or creeks in that region. The third day they came to what they called the plain of Guacoco, Florida's largest field of heavy sub-surface phosphate deposits, nature's fertilizer. That plain covered at least 130,000 acres of phosphate fields, the only one like it in all of Florida. The army gathered maize in quantity for the first time, having traveled over thirteen leagues from Myakka Lake. (Inca in Clayton 1993:II:224).
Cited From: http://www.floridahistory.com/inset5.html
The pre-Socratic philosophers of ancient Greece proposed water to be “the origin of all things.” By the time of Aristotle, the creative elements had increased by three, with the addition of earth, air, and fire. Modern science, however, affords special emphasis for the sustenance of life (if not its creation, which remains still a mystery) to two of these elements: fire and water.
The active force of solar radiation strikes our planet from the center of the solar system. This “fire” is the powerhouse that fuels photosynthesis and governs the movements of wind and wave. The reactive wells of the oceans provide the vast reserve of waters that – whether circulating in the seas or streaming down from distant mountain ranges – sustain the cells of biological life.
Though the ocean is an essentially passive element in this relationship, it remains the more essential. Though most animal life on earth is ultimately dependent upon photosynthesis, through the ingestion of plants or the ingestion of animals that have fed on plants, recent discoveries on the ocean floor reveal that some organisms, living in proximity to deep-water volcanic vents, are able to sustain themselves without any relationship to the sun whatsoever. Even these tiny creatures however, cannot do without water.
It is widely suspected that our biological ancestors originated in the world’s oceans. What we fail to appreciate, however, is that, in many ways, we never left.
The outpouring of life from the water to the land would not have been possible had the sea, through the hydrologic cycle, not provided a precedent. Water; composing almost 70% of our human bodies, literally flows through our veins. Thus, for all our reliance upon atmospheric gases, we remain, in a sense, marine organisms. Until the moon landings of 1969, life had gone nowhere that water had not gone before and, even then, water came along for the ride.
The continued presence and influence of our ancient, oceanic heritage becomes all the more apparent the more we investigate the chemical dependencies of life and the interactive relationship between land and sea.
Standing in view of the pounding surf, or watching helplessly as seeping, saline ground waters, slowly erode fertile coasts, it is all too easy for us to judge the ocean’s impact as irredeemably negative. Soils that sustained plants, animals and humans, once stolen from the land, sink to regions where only kelp and corals benefit. Yet, even for the seaweeds, the gift is fleeting, for, in short order, the fertile soil slips beneath the waters’ euphotic zone (the surface region of the ocean that sunlight penetrates) and descends to depths where photosynthetic processes cease -- and life, all but ends.
This negative view, however, comes of our tendency to picture the earth’s history from our apparently static viewpoint. When seen from a holistic perspective, the ocean reveals its true self: the source of all the earth’s fertility.
Already described in this essay are the positive effects of the hydrologic cycle, which makes possible the redistribution of minerals and nutrients. What has not been noted explicitly however is that these effects are accomplished by a force that is inherently erosive in character.
Rivers, despite the attention given them in this essay, are little more than the ocean’s proboscis upon the land – giant, amoeban arms, pawing at the continental earth in an eternal effort to return all to its liquid origin. The riverine deposit of soil, mineral and nutrient, is a consequence of the limited potency of this energy to accomplish its long-term erosive goal. Any respite afforded to transported material is always, only temporary. Ultimately, it is in the deep that all earth finds its end.
If rivers then, are the grasping arms of the sea, the surface waves and deep-water currents are its teeth. The erosive powers of the hydrologic cycle exceed those of waves only in reach. In strength, they cannot compete with the direct forces with which the ocean unrelentingly batters both shore and shelf. Yet, just as river erosion has its positive effects, so too does the erosion of the land by the sea.
Right now, off our modern coasts, land is slowly being stripped away and deposited on the sea floor. There, wave action, and the constant flow of near-shore currents, sifts and sorts the eroded soil both horizontally and vertically. The heaviest, most infertile sands remain near the beaches, while the lighter, more mineral-rich soils are transported far from the shoreline. When gravity lowers even these to the ocean floor, the particles arrange themselves in layers of increasing fineness from the bedrock upwards.
This process is comparable to the transportive properties of rivers, though it operates on a far more massive scale.
Much of this soil is destined to be lost to the deep ocean for eons of geological time; but not all of it. Where the continental shelf is sufficiently wide and flat, it acts as a catchment of sorts. Here, the silt settles into sinkholes and depressions in the surface, or spreads out finely over the shelf floor. Over time, the shelf will integrate much of this new material within its petrified sediments (which are formed of just these same materials, deposited over eons of geological time).
Of course, unlike silt deposited on the banks of the world’s rivers, silt that settles on the continental shelf, is beyond human exploitation. Yet, as we know, this is not destined to always be so.
The Eemian Interglacial period lasted approximately 30,000 years, and throughout that period, waves beat upon a shoreline that, in altitude, was approximate with our own. The elevated continental crust became grist in the ocean’s pounding mill for thirty millennia; its rocks, sands and gravels were ground ever finer, and were moved ever further toward the outer rim of the continental shelf. When the Eemian ended, the retreating water unveiled the result of its labor: perhaps the most finely milled soils anywhere in the world.
In the first part of this series, it was suggested that the periodic flooding of the continental shelf over multiple Inter-Glacial periods might have introduced unique properties within soils exposed during Glaciated conditions. Thus far, I have described how changes in ocean depth facilitated the effective distribution of valuable, eroded silts over the periodically flooded plains, and delayed the eventual decent of these fertile soils into the ocean’s desert deeps.
The appearance of marine deltas, during periods of ocean flooding, concentrated riverine silt deposits at the inner rim of the shelf for slow redistribution over the plains during glacial periods. Under low water conditions, the slackened pace of rivers flowing over the shallow incline of the continental shelf, allowed for the formation of massive, riverine deltas (similar to the Mississippi Delta of the Holocene). Finally (as described above) the pounding surf of floodwaters directly eroded the inter-glacial shoreline while bottom currents pushed finely ground sediments toward the continental edge.
The potential of these forces to infuse the Ice Age coastal plains with fertile soils certainly appears significant. Nevertheless, this essay has yet made no mention of what direct effects the periodic presence of 120 meters or more of water depth above much of the continental margin may have had upon the sediments formed below.
To understand the hidden potential of oceanic floods of this magnitude, we need look away from the oceans to some of the few places on earth where ground lain down under similar conditions may yet be found exposed in the Holocene world -- the last place we would think to find it: the earth’s mountain ranges.
On the slopes of mountains, hikers and climbers often stumble upon the fossilized remains of shellfish and other crustaceans. Such marine sediments were once thought to be evidence of “Noah’s flood.” Now we realize that these remains were deposited millions of years ago, when much of the world that is now continental landmass rested at the bottoms of vast oceans. Massive earth quakes and slow tectonic movements of the earth’s plates subsequently lifted some of these seabeds even to extreme altitudes.
It so happens that these marine deposits represent some of the world’s richest sources of a specific chemical compound of infinite value to all life on earth: phosphate.
A large part of the reason that rivers have historically been of such value to agriculture is the transport and distribution of natural phosphates that they facilitate. Eroded from ancient marine deposits by mountain streams, phosphates are delivered by rivers to the plains below, where they are deposited on the riverbanks by seasonal floods or artificial irrigation. It would not be an exaggeration to characterize Ancient Egypt as the offspring of phosphate deposits, carved from the mountains surrounding Lake Victoria.
Aside from water itself, no chemical element is more essential to plant life than phosphate. Its value cannot possibly be overestimated. The presence or absence of phosphate in soil is the principle factor by which its fertility is determined. Even the most irrigated and otherwise nutrient rich earth, if devoid of phosphate, will yield no plant life whatsoever.
Marine organisms, sitting at the gravitational bottom of the chain of life descending from the mountain peaks to the sea floor, are the last to make use of these compounds. What they fail to recycle sinks to the bottom as phosphate nodules. Under the right circumstances, these nodules will build up into sedimentary layers of nearly pure phosphate.
Miles below the surface of the ocean, a constant rain of biological material coats the lightless, barren ground in thick ooze. These soils, despite their enormous phosphate content, are out of reach of exploitation by all but bacterial life and are destined to lay fallow for millions of years (until far distant geological forces uplift the ocean floor to form new continents).
All of the biological rainfall that coats the bottom of the sea is produced by life forms inhabiting the ocean. Aside from alga fields that drift upon the surface, all the ocean’s first order biological activity is restricted to the very narrow margin of waters that wash the continental coastline. Beyond this margin, the ocean’s depth shields the sea floor from the penetrating sunlight needed for photosynthesis. Without the plant life that sunlight makes possible, the entire food chain collapses into an ecology characterized by single-celled organisms and other simple life forms, feeding on waste material drifting out from the shallows.
The Euphotic Zone, the watery region where photosynthesis remains possible, descends to a depth of roughly 100 meters, though some limited photosynthetic activity may take place a short depth below this line and much of it ends far above it.
During glacial periods, the waters of the ocean practically lapped against the outer rim of the continental shelf. Not far from this glacial era coast, the land dropped very rapidly over a submarine cliff edge. Consequently, marine biological activity was concentrated in an even narrower strip than it is today and it’s waste material, was quickly dumped to extreme depths.
In inter-glacial priods, two related phenomena insured that the desent of this biomass was not so rapid.
First, the shallow, flat shelves supported a wider expanse of marine biology. This insured more recycling of biomass by renewal of the submarine soils. Fertilizing compounds, drifting out from the beaches, settled on ground still suitable for plant growth. Thus, the local ecology retained the valuable nutrients contained therein, and slowed their eventual loss from the earth's life-cycle.
Secondly, and perhaps most importantly, during inter-glacial periods, the ocean bottom was effectively lifted to a mere 20 meters below the Euphotic zone. Though biological waste materials from the coasts continued to spill over the cliff face of the continental shelf, much of it was thus retained on the cusp of the margin itself, and in a fallow state. The vast, plant free ledge that, in places, extended out and under the Euphotic zone for miles, thus captured a good portion of the phosphate rich, biogenous ooze that would normally have sank directly to the ocean bottom. The resulting fertilization of the shelf with biomass persisted for tens of millennia. The depth at which this retention occurred – somewhere between the outer limits of vegetative photosynthesis and bacteriological purification – insured that the phosphate-infused soils would lie unexploited throughout that time.
Another phenomenon of interest augmented the effects of biomass retention afforded by the flooding of the continental margins.
During both glacial and inter-glacial periods, deep, turbulent currents, passing along the bottom of the shelf edges, disturbed ocean-floor deposits of undeterminable age – deposits mixed in a thick soup of biological waste material that had poured for millennia, in a slow but steady stream, down from the high cliffs above. Those deep currents crashed against the barricades of the shelf margins and “up welled” this material in wave-like thrusts.
In glacial periods, because water depth above the shelf was so shallow, and the shelf margin itself so thin, most of this mineralogically invaluable material immediately drifted back down over the cliff face, lost again to the depths. But during Glacial periods, these deepwater currents had room to crest over the lips of the cliff faces and spill their material directly on the continental shelf.
Thus, a unique mix of fertility-boosting forces combined on the continental margins during periods of inter-glacial flooding. From the shoreline, river silts, together with soils eroded from the shore by wave action, were refined, and conveyed by currents toward the outer margins of the shelf. At the same time, biological material, produced in exceptional abundance, slowly made its way through the local ecology to sink and lie fallow on the same shelf margin. A third wave of ancient mineralogical and biological material, up welling from miles below the water’s surface, collided with both these forces.
Of course, a great deal of the phosphate-rich, finely milled mineral ooze, produced by this combination, was eventually lost to the depths. Nevertheless, where the continental margin was of sufficient size, much of it was retained. Eventually, the sediment of the shelf incorporated much of this mixture. The remainder rested upon the surface in the form of rich alluvial soils.
It is the suggestion of this paper that, when the last great Ice Age began, and the Eemian inter-glacial floods receded, the coastal flats thus exposed were home to the most fertile soils the world has ever known. Furthermore, because of the current-driven distribution of the formerly submarine materials, the best of these soils were concentrated at the Ice-Age shoreline.
The Eemian, of course, did not alone create this happy-assembly. Rather, the last inter-glacial merely produced the latest inundation in a cycle spanning hundreds of thousands – and perhaps millions – of years. Each of these floods left similar deposits on the shelf and, over time, this material became a permanent fixture of the shelf’s sediment.
In human memory, soils such as these have never been equaled.
When we emerged from Africa, in the last great exodus from that continent, a lush but doomed, “Garden of Eden” awaited our arrival; and beckoned us to tarry there, along the coastal plains.
Next week, in the final part of this series, Christopher e/xamines what implications the "God's Garden Hypothesis" might have upon theories of agricultural development - and how these square quite nicely with Underworld's settlement scenario.