1. AA&A Spring 20021

2. 2 Archaeological Prospecting What have you got? Where do you look? Where do you dig??? –*Aerial photography –*Electrical resistivity –*Magnetometry –*Ground penetrating radar (GPR) –Electromagnetic induction –Seismic probes (sonar) –Gravimetry –Gamma “radiography” –IR emission imagery Archaeology without a shovel

3. AA&A Spring 20023 What are the clues? Shadowing

4. AA&A Spring 20024 Soil marking Filled ditches- More moisture Roman roads- Paving-less moisture

5. AA&A Spring 20025 Crop or vegetation marking Roman villa

6. AA&A Spring 20026 Mystery photo Frost crack patterns from time of permafrost

7. AA&A Spring 20027 Familiar territory

8. AA&A Spring 20028 Less familiar

9. AA&A Spring 20029 Zoom out

10. AA&A Spring 200210 What is it? Nazca, Peru 200 BCE-600 CE Rocks removed to reveal lighter colored subsoil No rhyme or reason to complex array of lines photo

11. AA&A Spring 200211 Aerial photo-hummingbird

12. AA&A Spring 200212 Spider

13. AA&A Spring 200213 Sketches of others

14. AA&A Spring 200214 Geometric patterns

15. AA&A Spring 200215 KerkenesKerkenes, Turkey: ~585-545 BCE

16. AA&A Spring 200216 Kerkenes-aerial view

17. AA&A Spring 200217 1,400,000 GPS points

18. AA&A Spring 200218 Reconstruction from GPS data

19. AA&A Spring 200219 Closer aerial photo-interior

20. AA&A Spring 200220 How to see without digging? Want to use electrical conductivity: –Good insulators–dry brick, non-porous stone, glass, voids, dry soil –Good conductors–metals –In between (a tremendous range)–moist brick or soil, water A way to measure conductivity of what’s underground??? Activities of man-----subsurface inhomogeneities

21. AA&A Spring 200221 Currents in homogeneous soil + _

22. AA&A Spring 200222 = local high conductivity + _

23. AA&A Spring 200223 Where is it? _ + _ + _ +

24. AA&A Spring 200224 How deep is it?? + __ + Sensitive to depths ~ 1.5 x separation

25. AA&A Spring 200225 What do you see? =???? Higher conductivity –Higher moisture content –More dissolved minerals –Metal artifacts Lower conductivity –Lower moisture –Masonry –Voids

26. AA&A Spring 200226 Conductivity array

27. AA&A Spring 200227 Conductivity data 20 meter grid

28. AA&A Spring 200228 Magnetometry How to look for magnetic materials? Simplest of magnetometers is a compass

29. AA&A Spring 200229

30. AA&A Spring 200230 Magnetometry Earth’s field Buried object Surface Signal Magnetometer

31. AA&A Spring 200231 Magnetic gradiometer Earth’s field Buried object Surface Difference Signal difference Gradiometer

32. AA&A Spring 200232 Magnetometry Sense variations in Earth’s magnetic field need high sensitivity killed by fluctuations in time Solution: magnetic gradiometer pair of sensors look only at difference Sensitivity of the best (not the one illustrated): 10 -8 of Earth’s field!

33. AA&A Spring 200233 What do you see? Local variation in magnetism Most obvious–iron artifacts Recall colors of unglazed pottery –Red–hematite–Fe 2 O 3 –non-magnetic–“oxidized” –Black–magnetite–Fe 3 O 4 –magnetic–“reduced” Magnetite containing soil –Soil replaced by stone masonry or red brick –Ditch or earthworks filled in by non-magnetic soil –Alignment of grains in clays disturbed by working –Soil disturbed (e.g., a grave) allowing oxygen access Hematite containing soil –Reduction of iron in fire hearth –Destruction of building by major fire

34. AA&A Spring 200234 6-element gradiometer

35. AA&A Spring 200235 Real data Conductivity Magnetometry

36. AA&A Spring 200236 Columned hall

37. AA&A Spring 200237 Electromagnetic induction Otherwise known as metal detectors

38. AA&A Spring 200238 Electromagnetic induction Resistivity EM Induction

39. AA&A Spring 200239 Aerial photo

40. AA&A Spring 200240 100 meters Magnetic survey

41. AA&A Spring 200241 Ground Penetrating Radar = GPR How did we see below the surface of a painting? Used Infra-red light to penetrate surface layer and see how it interacts with deeper layers. Radar uses “light” of MUCH longer wavelength to penetrate soil.

42. AA&A Spring 200242 Electromagnetic waves

43. AA&A Spring 200243 Radar Distance = (travel time)/(twice velocity of light) 10 microseconds  1 mile 2 nanoseconds  1 foot

44. AA&A Spring 200244 Can energy really go from here to there???

45. AA&A Spring 200245 WE SUGGEST THAT YOU TURN OFF YOUR LAPTOPS AND WIRELESS DEVICES (INCLUDING CELL PHONES)