PowerPoint PresentationSlide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Cycles of erosion and soil formation beginning with Bronze Age erosion after introduction of plow-based agriculture.Population of the Southern ArgolidSlide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Maya population, vegetation, and soil erosionSlide 27Slide 28Slide 29Slide 30Slide 31Slide 32Slide 33Slide 34Slide 35Slide 36Slide 37Slide 38Slide 39Slide 40Palouse, WashingtonSlide 42Slide 43Slide 44Slide 45Slide 46Slide 47Slide 48Slide 49Simplest model of time required (Tc) to lose soil thickness (S) as a function of difference between erosion (E) and soil production (P)Slide 51Slide 52Slide 53Slide 54Slide 55Slide 56QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.MesopotamiaMinoansGreeceRomeIndusAngkor WattOlmecMayaInca Civilizations around the world have risen and declined. How much did past societies contribute to their own decline?Can soil erosion limit the lifespan of civilizations? Recognizing that >97% of our food comes from the soil, the fundamental condition for sustaining a civilization is sustaining the soil. What would be required to sustain a civilization?Politics, Social Evolution, and ContextEvery civilization has a unique historical and social setting and the specific social contexts that lead to warfare and institutional evolution/crises. QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.Climate ChangeQuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.Volcanos, Earthquakes, and FloodsQuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.Natural DisastersClimate ChangePolitics and Social EvolutionQuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.No particular time scale implied by:Salinization, Overgrazing, and DeforestationQuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.Deforestation often blamed for historical soil erosion, but trees grow back rapidly…QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.Recent archaeological studies have showed that soil erosion played a role in the demise of ancient civilizations of Neolithic Europe, Classical Greece, Rome, the Southern United States, and Central America.Major civilizations last about 500 to 2000 years…Invention of the plow fundamentally altered the balance between soil production and soil erosionIn the permanence …of a coat of vegetable mould on the surface of the earth, we have a demonstrative proof of the continual destruction of the rocks; and cannot but admire the skill, with which the powers of the many chemical and mechanical agents employed in this complicated work, are so adjusted, as to make the supply and the waste of the soil exactly equal to one another. - [Playfair, 1802, p. 106-7]Zground surface colluvium/soil,ρszbH soil production~qsfrom bedrock, εsaprolite, fractured,and coherentbedrock,ρrXhWeathering frontGeomorphology simply:TectonicsQtzs+⋅∇−=∂∂~Heimsath et al. (1997)Conventional plow-based agriculture increased soil erosion by more than an order of magnitude…Cycles of erosion and soil formation beginning with Bronze Age erosion after introduction of plow-based agriculture.Van Andel and Runnels (1987)Population of the Southern ArgolidVan Andel and Runnels (1987)Bronze AgeModern AgeClassical AgePlato[T]he rich, soft soil has all run away leaving the land nothing but skin and bone. But in those days the damage had not taken place, the hills had high crests, the rocky plain of Phelleus was covered with rich soil, and the mountains were covered by thick woods, of which there are some traces today. 427-347 B.C.Erosion rates in the Roman heartland increased by an order of magnitude starting about the 2nd century B.C.Judson (1963; 1968)It is also a science, which explains what crops are to be sown and what cultivations are to be carried out in each kind of soil, in order that the land may always render the highest yields. [Varro, 1:3]You have all traveled through many lands; have you seen any country more fully cultivated than Italy? [Varro, 1.2.6]Roman ruins in Northern SyriaRome’s North African colonies supported extensive olive and cereal plantations in the 1st through 3rd centuries A.D.Goodchild (1953)All places are now accessible, well known, open to commerce. Delightful farms have now blotted out every trace of the dreadful wastes; cultivated fields have overcome woods.... We overcrowd the world. The elements can hardly support us. Our wants increase and our demands are keener, while Nature cannot bear us. - [Tertullian, de Anima, 30]George Perkins MarshMan and Nature (1864)A widely traveled Vermont lawyer, Marsh argued that people were reshaping Earth’s surface and that civilizations influenced their own fate through deforestation, soil erosion and degradation, and water pollution.[T]erritory larger than all Europe, the abundance of which sustained in bygone centuries a population scarcely inferior to that of the whole Christian world at the present day, has been entirely withdrawn from human use, or, at best, is thinly inhabited. … There are parts of Asia Minor, of Northern Africa, of Greece, and even of Alpine Europe, where the operation of causes set in action by man has brought the face of the earth to a desolation almost as complete as that of the moon; and though, within that brief space of time which we call “the historical period,” they are known to have been covered with luxuriant woods, verdant pastures, and fertile meadows…. -[Marsh, 1864, p. 9, 42]Walter LowdermilkOver a large part of the ancient granary of Rome we found the soil washed off to bedrock and the hills seriously gullied as a result of overgrazing. Timgad, LibyaQuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.Overall, average annual soil erosion rates during the Maya period were > 5 t/ha over more than 2200 years, more than an order of magnitude faster than natural soil regeneration. QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.Lago Salpeten, GuatemalaMaya population, vegetation, and soil erosionDeevy et
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