> > > JDG wrote: > > > So far, our three examples of "collapse", > > Easter, Pitcairn, and > > > Chaco Canyon have all shared the feature of > > >being settled in a > > > marginal environment. Is a marginal environment > > >a prerequisite for "collapse"?
I think that's a good starting point for this chapter. Compared to the 3 places above, the Yucatan is less fragile, less isolated and has more variations or diversity, which ought to provide a better buffer against degradation. Nevertheless, Diamond points out that the land is mostly karst, which is porous limestine and holds water poorly, is a seasonal tropical forest with a 4-month dry season, and has somewhat erratic rainfall patterns that cause crop failure even now. Mayan adaptations to these conditions included construction of reservoirs (at Tikal, enough capacity to provide drinking water for 10 thousand people, for 18 months!), use of canals, irrigation and terracing to improve crop yields, and a society structured to provide enough peasant labor that allowed central authorities to indulge in various cultural entities such as city-building, writing and art. Diamond proposes that because of their more limited crops, diet, and ability to transport food for armies (compared to the Aztecs and Inca), the Maya were unable to have a single central ruling body. The result was essentially ongoing if stuttering warfare, as I understand it. Competition to create better temples and monuments appears to be a factor in deforestation of some parts of the Yucatan; they made quantities of limestone plaster that required a lot of wood fuel. This abstract gives a brief description of Neolithic plaster technology: http://www.bu.edu/jfa/Abstracts/K/KingeryW_15_2.html W. David Kingery, Pamela B. Vandiver, and Martha Prickett The Beginnings of Pyrotechnology, Part II: Production and Use of Lime and Gypsum Plaster in the Pre-Pottery Neolithic Near East Journal of Field Archaeology 15 (1988) 219--244 Characterization techniques of modern materials science have been used to extend a prior study (W. H. Gourdin and W. D. Kingery, "The Beginnings of Pyrotechnology: Neolithic and Egyptian Lime Plaster," Journal of Field Archaeology 2 [1975]: 133--50) of plaster materials and their processing in the Pre-Pottery Neolithic (ca. 7200--6000 B.C.). The "invention" of lime plaster can be traced back to at least the Epi-Paleolithic Geometric Kebaran (ca. 12,000 B.C.) and its use in architecture to the Natufian (10,300--8500 B.C.). The production of lime and gypsum plasters is described as a multi-step process requiring selection and collection of raw materials, heating of limestone at 800--900 degrees C (gypsum at 150--200 degrees C), slaking the quicklime in water to form the hydroxide, mixing with various additives, applying and shaping as a paste, and often coating with a slip coat and burnishing---a skilled craft activity having some structural similarities to pottery manufacture... An aside, but interesting I think- This is about using satellite tech to find Mayan ruins: http://www.nsstc.org/news/msfc_nr_02_15_06.html ...Sever has explored the use of remote-sensing, the science of collecting information about the Earths surface using aerial or space-based photography, to serve archaeology. He and Irwin provided Saturno with high-resolution commercial satellite images of the rainforest, and collected data from NASAs Airborne Synthetic Aperture Radar, an instrument flown aboard a high-altitude weather plane, capable of penetrating clouds, snow and forest canopies. These resulting Earth observations have helped the team survey an uncharted region around San Bartolo, Guatemala. They discovered a correlation between the color and reflectivity of the vegetation seen in the images their "signature," which is captured by instruments measuring light in the visible and near-infrared spectrums and the location of known archaeological sites. In 2004, the team ground-tested the data. Hiking deep into the jungle to locations guided by the satellite images, they uncovered a series of Maya settlements exactly where the technology had predicted they would be found.... ...The cause of the floral discoloration discerned in the imagery quickly became clear to the team. The Maya built their cities and towns with excavated limestone and lime plasters. As these structures crumbled, the lack of moisture and nutritional elements inside the ruins kept some plant species at bay, while others were discolored or killed off altogether as disintegrating plaster changed the chemical content of the soil around each structure. "Over the centuries, the changes became dramatic," Saturno said. "This pattern of small details, impossible to see from the forest floor or low-altitude planes, turned out to be a virtual roadmap to ancient Maya sites when seen from space..." And these articles have some pix: http://www.thepanamanews.com/pn/v_12/issue_04/science_06.html http://www.nasa.gov/vision/earth/lookingatearth/mayan_ruins.html I stumbled across these in hunting for articles on deforestation and lime plaster - ? applicable to subject. Erosion in ancient Greece: http://www.bu.edu/jfa/Abstracts/V/VanAndelTj_17_4.html Tjeerd H. van Andel, Eberhard Zangger, and Anne Demitrack Land Use and Soil Erosion in Prehistoric and Historical Greece Journal of Field Archaeology 17 (1990) 379--396 Soil erosion resulting from human exploitation of the land has attracted much public and scientific interest. Being regarded mainly as a modern phenomenon, however, its prehistoric and historical extent remain largely unexplored. Here we summarize three regional studies of Holocene erosion and alluviation in Greece, together with information derived from the literature, and conclude that most recorded Holocene soil erosion events are spatially and temporally related to human interference in the landscape. Wherever adequate evidence exists, a major phase of soil erosion appears to follow by 500--1000 years the introduction of farming in Greece, its age depending on when agriculture was introduced and ranging from the later Neolithic to the late Early Bronze Age. Later Bronze Age and historical soil erosion events are more scattered in time and space, but especially the thousand years after the middle of the 1st millennium B.C. saw serious, intermittent soil erosion in many places. With the exception of the earliest Holocene erosion phase, the evidence is compatible with a model of control of the timing and intensity of landscape destabilization by local economic and political conditions. On the whole, however, periods of landscape stability have lasted much longer than the mostly brief episodes of soil erosion and stream aggradation. This is an abstract about deforestation in the Fertile Crescent area: http://www.bu.edu/jfa/Abstracts/H/HughesJ_10_4.html J. Donald Hughes Deforestation, Erosion, and Ecology in the Ancient Mediterranean and Middle East: Contribution 1 (1974) How the Ancients Viewed Deforestation Journal of Field Archaeology 10 (1983) 437--445 Severe deforestation in the Mediterranean basin was described by classical authors. The background to their comments was the traditional view that groves of trees were sacred to the gods and that forests were the original home of mankind. The causes of deforestation, according to ancient writers, included agricultural clearance, pastoralism (especially that involving the goat), commercial tree cutting, warfare, and other human uses. The results included interference with water supplies, soil erosion, climatic changes, agricultural decline, and shortages of wood. Efforts were made to counteract some of these effects, including diplomatic maneuvers to secure supplies of timber, conservation mesures, legal enactments, and the protection of certain forest areas as reserves or ascred groves. Many of the people in antiquity held that trees were inhabited by supernatural beings, or possessed souls of their own, but most pholosophers adopted a more pragmatic view. In practice, the pressures of human use triumphed over traditional attitudes of respect and preservation, resulting in a chronic process of deforestation and erosion. Well, I've got to go, so will send this incomplete post; my rank tyro interpretation of the Mayan collapses is that they had more to do with bad societal choices, with environment degradation a lesser cause (although some of those choices led to deforestation and so on). Tag! Debbi More When I Get Back On-line Maru __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com _______________________________________________ http://www.mccmedia.com/mailman/listinfo/brin-l
