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Geoarchaeology

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  1. Geoarchaeology Studying Ancient Environments

  2. Ancient Environments • Geology: numerous techniques for studying ancient environments (four main approaches) • Petrology: studying characteristics of stone • Geomorphology: studying ancient landforms • Sedimentology: studying soil processes • Climatology: studying ancient climate change

  3. Petrology • How rock changes over time (weathering, erosion) • Can help with determining age of material culture • Source Areas (where raw materials originated) • Thin Section Analysis • Looking for characteristic inclusions and crystals • Analysis of trade, exchange, social interaction, migration • Trace Element Analysis • X-Ray fluorescence, Neutron Activation Analysis, etc. • Energize sample to stimulate emission of characteristic trace element spectra; can then be tied to a source area

  4. Thin Section Examples Pottery Stone

  5. Geomorphology • Today’s landscape not always what it was in the past • Landscape one factor in determine available resources • Plants, animals, stone, etc. • Understanding landscape and resources helps us understand what sort of world ancient people lived in • Changes in landscape affect archaeological record • Patterns of deposition/erosion bury or destroy sites • e.g., Glaciation, River Erosion, Flood Deposition

  6. Geomorphology of Ancient Shorelines

  7. Sedimentology • Nearly all archaeological sites buried • Need to understand soil processes • How deep do you have to dig? Depends on nature of soils (key to research design; determines how one surveys for and excavates sites) • Floodplain (deeply buried); Terrace (intermediate); Uplands (shallow deposition) • What comprises culturally sterile deposits? • North America: e.g., glacial gravels • Classification of soil stratigraphy • Plowzone (Ap), A horizon, B horizon, C horizon; “buried A horizons”

  8. Soil Stratigraphy

  9. Climatology • Climate: another major factor in determining available resources • Desert, forest, swamp, prairie, etc. • Ecofacts: primary means of determining climate • Floral and Faunal Analysis • Dendrochronology (a record of climate as well as time) • Recovery by flotation • Seeds, microfauna, wood frags., nut frags., etc. • Pollen/Palynology; Phytoliths • Isotopic evidence • Stable Oxygen isotopes in Ice Cores • Ice Age(s) example

  10. Environmental Indicators Pollen Phytoliths Animal Bone Plant Remains

  11. Case Study in Geoarchaeology The Sphinx: How Old is It?

  12. “Great Sphinx” • Located on Giza Plateau, outside Cairo • Memphis Necropolis (includes Great Pyramids)

  13. Age Debate • Mainstream History of Monument • Built at same time as nearby Pyramid of Khafre (Khaf-Ra, Chephren) in about 2540 BC (face thought to be Khafre) • Early documentary references: 1500 BC • Construction of monument part of the same program monument construction during the first five centuries of the Old Kingdom (2575-2134 BC) • Origins of Pharaonic dynasties • Monuments as legitimating social hierarchy

  14. Age Debate • Controversial Reinterpretations: “Old Sphinx” • John Anthony West (“Amateur” Egyptologist): weathering patterns consistent with water, not wind • Especially for lower levels of monument (supposedly buried by sand longest, so contain most evidence of “water-weathering”) • Area has been arid since 10,000 BC, so Sphinx must be at least that old (and related to “Atlanteans”) • Some geologists (e.g., Robert Schoch) have supported the weathering theory • Graham Hancock: pyramids and sphinx locations relate to 10,500 BC stellar alignments • No recorded builder or building date (minor references that it may predate pyramids, but not by how long)

  15. West and Schoch (Never trust someone wearing a pith helmet)

  16. Age Debate (cont.) • Gauri et al. (geoarchaeologists): similar patterns to West’s “water-weathering” occur in arid environments also • West and Schoch ignore basic geology of area • Sphinx carved out of local bedrock; geologic characteristics of upper layers (head) different than bottom (body) – increase in porosity in lower parts • salt crystals form in rock pores; causes exfoliation due to hydrostatic pressure; same patterns as West’s “water-weathering”

  17. Age Debate • Critiques of Old Sphinx argument • No associated artifacts older than 2,600 BC • If a technologically sophisticated culture existed prior to that, you would expect to find some traces beyond a single monument; Where’s their garbage? • West argues that Sphinx water weathered, while other monuments wind weathered • Why haven’t “wind weathering” patterns obliterated older, “water weathering” patterns?

  18. Geology of the Sphinx

  19. How to spot Pseudoscience • Prior Plausibility: how well does a theory fit with what we already know? • Occam’s Razor: simpler explanations should be preferred over complex • Non-sequitur argument: “They laughed at <insert name>, and he was right, so I must be right also” • Public Verifiability: can other people apply the ideas and get the same results? • Authority: who is the person making the argument? • Humility: not to say that all good scientists are humble, but a crackpot is almost never humble • $$$: is someone getting rich off of their claims?