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Geophysics in Archaeology
- 1. Geophysics in ArchaeologyGeophysics in Archaeology A scrapbookA scrapbook of worldwide dataof worldwide data Adam O’Neill
- 2. The sitesThe sites GuatemalaGuatemala ++ El SalvadorEl Salvador Pompeii,Pompeii, ItalyItaly TurpanTurpan,, ChinaChina JapanJapan
- 4. Ground Penetrating RadarGround Penetrating Radar 200 MHz 50 MHz 450 MHz ~10-15 cm / 2 m <5 cm / < 1 m +50 cm / +5 m Resolution / Max. depth Tx Rx www.gpr-survey.com Typical hyperbolic diffraction
- 6. MagneticMagnetic gradiometrygradiometry Earths field Induced field Vertical magnetic gradient (nT/m) Sensors Iron objects (swords, tools) Remanent magnetism (kilns, bonfires)
- 8. EmaEma CastleCastle Kamioka town, northern Gifu prefecture Built in 1400’s by Lord of Northern Gifu Destroyed by fire 1582 Chinese and Japanese pottery from 1200’s to 1500’s Large trapezoidal and triangular moats GPR surveys in 1994 and 1997
- 10. GPR north moatGPR north moat Line 5 Trapezoidal moat 100 MHz
- 11. GPR west moatGPR west moat Lines 6&7 Triangular moat 100 MHz Goodman (1994) GPR modelling
- 12. Time migrationTime migration 50 MHz Migrated Clear V-shape
- 13. MountMount ZoubiZoubi Yoro Town, southern Gifu prefecture 3rd to 6th century Oldest burial mound tombs of Kofun period On major east-west military junction Sites of many battles Largest mound at hill summit
- 14. Magnetic surveyMagnetic survey Dipolar anomaly! FM18 vertical fluxgate gradiometer
- 15. GPR surveyGPR survey Hyperbolic anomaly Metallic source Second anomaly 1 m deeper again 200 MHz Gradiometer: Width at half-amplitude ~source depth
- 16. GPR cubeGPR cube Target 1: Metallic response Target 2: Underlying anomaly Archaeologists very interested! E W
- 17. Excavation surveyExcavation survey Excavated sword fragments Post excavation survey Secondary target revealed Burial? Swords removed Swords location 450MHz
- 18. KomochiKomochi VillageVillage Komochi Village, Gunma prefecture Burial mounds of Kofun period, 300-700 AD Mt. Haruna erupted twice in 6th century ‘Pompeii of Japan’ Burying kofun up to 4 m in ash and pumice
- 19. GPR reconnaissanceGPR reconnaissance 200 MHz 100 MHzCMP location Large kofunSmall kofun
- 20. Two frequency GPRTwo frequency GPR 200 MHz 100 MHz Burial chamber? Surrounding moat?
- 21. Burial moundsBurial mounds Burial chamber reconstruction Exposed kofun Typical size and shape GPR modelling Goodman (1994)
- 23. Other tumuliOther tumuli Giant keyhole Double-mounds/ Clusters RectangularSingle mound
- 26. TurpanTurpan Far northern desert On the ‘Silk-road’, Middle-east to Asian trading route Early Kingdoms (from 1st century BC) Later Mongolian rule (13th-14th century AD) Autonomous ruling from 1954 Excavations in 1930: 120 tombs, 800 artefacts Excavations in 1994: Pure gold crown
- 27. Aerial photographyAerial photography 13 m3 helium blimp Tombs grouped into family clusters
- 28. GPR linesGPR lines 100 MHz antennas pulseEKKO IV
- 29. GPR sectionsGPR sections 100 MHz Line 9 Line 10
- 30. Fence displayFence display Excavation: Sloping entrance to tomb
- 31. Electrical and EMElectrical and EM EM38 conductivityRM15 twin resistance 3436 Two resistive anomalies
- 32. FollowupFollowup GPRGPR 100 MHz RM15 resistance Buried cavity? (multiples) Line 34 Line 36 Surficial anomaly? 100 MHz
- 34. Central AmericaCentral America Kaminaljuyu: 500 BC-1000 AD Mongoy: earlier (?) Joya de Ceren: 590 AD Chalchuapa: older (?)
- 35. Guatemala CityGuatemala City Mayan civilisations, buried by volcanic ash Kaminaljuyu: 500 BC-1000 AD Mongoy: has older black soil cover, earlier Pacaya volcano 25 km to south Active from 3000-700 years BP Parasitic eruptions in 16th C Horse bones, Spanish conquest
- 36. Guatemala CityGuatemala City Kaminaljuyu Archaeological Park Mongoy Mound
- 37. KaminaljuyuKaminaljuyu Survey area: Flat ground between mounds
- 38. Electrical andElectrical and magneticsmagnetics RM15 resistance FM18 gradiometer Coincident resistance and magnetic linear anomaly Clear edges of large platform or foundation
- 40. Electrical surveyElectrical survey RM15 resistance Shallow platform revealed
- 41. Targets and excavationsTargets and excavations Waste pits: Many artefacts recovered Topographic contours Site excavation map
- 42. El SalvadorEl Salvador Joya de Ceren: Agricultural village, 40-50 families Clay construction Loma Caldera tuff ring 600 m to north Erupted during rainy season of ~590 AD Chalchuapa: Political centre Stone construction Pyramid mounds and defensive walls
- 43. JoyaJoya dede CerenCeren Thick clay walls On raised foundations
- 44. GPR profilesGPR profiles 100 MHz 50 MHz Buried structure On raised platform
- 45. InterpretationInterpretation 100 MHz 50 MHz Thatched roof collapse Ash drapes over clay walls
- 47. GPR surveyGPR survey Mound 5 Typical section Burial cache 100 MHz 50 MHz
- 48. GPR surveyGPR survey Mound 2 50 MHz Construction cutaway
- 49. Boundary wallsBoundary walls 100 MHz 50 MHz Excavation Slope of rock wall
- 51. PompeiiPompeii Mount Vesuvius eruption August 24, AD79 Rediscovered 1748 Over two-thirds excavated and restored Some boundary fortifications remain buried
- 52. Mount VesuviusMount Vesuvius Most famous site buried by volcano Victims seared by hot gas and ash
- 53. AshAsh isopachisopach PompeiiAD79 Modern soil 1000 AD – 1900 AD eruptions
- 54. Survey linesSurvey lines Unexcavated part: Expected buried boundary walls of the Porta di Capua
- 55. MultiMulti--surveyssurveys Line 30 EM31 deep 200 MHz 100 MHz Ash flow North South Dipping layers Resistivity VEx5
- 56. ElectricalElectrical modellingmodelling Numerical result Synthetic model Field data Multiple techniques essential GPR alone not always enough 100 MHz GPR Line 150
- 57. Fence displayFence display Diffraction from top of wall aligns across sections
- 58. Summary and acknowledgementsSummary and acknowledgements Geophysics and archaeology: Essential integration Prefer multi-methods (GPR-resistivity-magnetics-EM) Try to use more than one GPR frequency Get in before excavations start !!! Yasushi Tanaka, Tanaka Geological Corporation Dr. Dean Goodman, Geophysical Archaeometry Lab. http://www.gpr-survey.com
- 59. OtherOther
- 60. ChatanChatan AirbaseAirbase Okinawa main Island Post war occupation US airbase Base designated for closure and repatriation to local families Archaeological surveys required for: (i) Cultural heritage mapping (ii) Pre-war land ownership boundaries
- 61. GPR surveyGPR survey Pipes and other modern clutter Anomaly of interest 200 MHz raw Migrated
- 63. Time slicesTime slices 200 MHz raw Migrated Focused anomaly Clear pipes
- 64. OtherOther
- 66. Velocity effectsVelocity effects Too slow (0.06 m/ns) Correct (0.095 m/ns) Too fast (0.11 m/ns)
- 67. OtherOther
- 68. SanSan XiaXia Yangtse River (Chang Jiang) From 2 million years B.P. to Ming Dynasty (13th-17th C B.C.) Several thousand years of civilisation ‘Three Gorges Dam’ over 170 m high Over 1 million people displaced Over 800 sites will be flooded Over 10000 tombs expected Villages still present, difficult surveying
- 70. Dam from spaceDam from space
- 71. EM and GPREM and GPR EM38 conductivity 100 MHz Anomaly!
- 72. More GPRMore GPR 100 MHz Real opportunitiy for archaeo-geophysics!
- 73. OtherOther
- 74. PrePre--exacavationexacavation surveysurvey RM15 resistance Good access Many lineaments Shallow platform revealed Waste pits
- 76. OtherOther
- 77. AcknowledgementsAcknowledgements Yasushi Tanaka, Tanaka Geological Corporation Prof. Toshi Matsuoka, Kyoto University Dr. Dean Goodman, Geophysical Archaeometry Lab. http://www.gpr-survey.com OYO Corporation, Japan (Chatan data) West Australian Maritime Museum (Abrolhos Island data) University of Western Australia