Scientific Tools for Probing the Past

Sven Isaksson Archaeological Research Laboratory Department of Archaeology and Classical Studies Stockholm University Scientific Tools for Probing the Past

Archaeology and Chemistry • Why a little chemistry is useful to archaeologists: • The archaeological sources are material remains – chemistry is the study of matter and its change • Material remains are affected by the ravages of time – what is left and how it is preserved • Man has always made use of matter and changed it; Man – the Chemist

History C. 1800, first chemical analyses 1896, first physical analyses 1945 New techniques in chemistry, physics and biology 1949, 14C-dating 1970 Increased application in archaeology 1985 Break-through in organic analyses

Archaeological Research Laboratory Established in 1976 Professorship in 1986, first as an adjoining position but later as a regular chair, in laboratory archaeology (swe: laborativ arkeologi) Since 2005 part of the newly created Department of Archaeology and Classical Studies

Department of Archaeology and Classical Studies Archaeological Research Laboratory Classical Studies Numismatic Research Group Osteoarchaeological Research Laboratory Archaeology

Scientific tools are used to probe the archaeological material for more data Archaeology! Not Archaeology? Not science? Science!

The Fate of Finds • Excavation • Semi-stable equilibriums are broken, collection, registration • Recording • Cleaning, visual characterization • Conservation • Halt decomposition, extract information • -excavation on microscopic level • Storage • Keep, preserve, display • Scientific analyses? • Excavations on molecular or atomic level

The nature of archaeological material

Contamination during excavation Hawaiian Tropic (coconut oil, UV-block).

Contamination during recording Day Cream (palm-tree oil etc)

Contamination during conservation From Aveling 1998 Paraffin

Keeping in museums Ancient horse DNA from Birka Excavated aDNA mtDNA HTG10 HTG8 Late 1800-tal + - - Late 1900-tal + + + From Götherström 2001 Alkanoic acids in Norwegian organic residues Is organic residues better off in the ground than in the museum?!

Analytical techniques Prospecting Dating Characterization

Prospecting Site locating

Prospecting Site locating Site investigating

Prospecting Site locating Site investigating Detecting anomalies from natural background

Prospecting Site locating Site investigating Detecting anomalies from natural background Geochemical – e.g. phosphate Geophysical – e.g. slingram, magnetometer and ground penetrating radar

Modellering efter georadar-prospektering Gamla Uppsala kyrka Nutida kyrkan

Modellering efter georadar-prospektering Gamla Uppsala kyrka Nutida kyrkan med tolkningen av katedralens utsträckning

Modellering efter georadar-prospektering Gamla Uppsala kyrka Undersökningsytorna

Modellering efter georadar-prospektering Gamla Uppsala kyrka Reflexer på 0 -0,6 m djup

Modellering efter georadar-prospektering Gamla Uppsala kyrka Reflexer på 0,2-0,8 m djup

Dating To fix an event along a time axis

Dating To fix an event along a time axis But what event?

Dating To fix an event along a time axis But what event? The event dated by an analytical technique is not always the same as the archaeological event…

Dating

Dating Method Material Range (yrs) Sample size Chronological Find combination artefacts 106 - Dendrochronology wood 104 100 treerings Magnetic TRM burnt clay 104, or longer cm DRM sediment Radiation damage Fission tracks glass, mineral 102…107 mm TL ceramic, br. stone 102…105 mg…g OSL sediment 106 mg…g ESR enamel 103…106 mg…g Radioactive decay Conventional 14C organic 50 000 10 g Accelerator 14C organic 70 000 mg K/Ar mineral 105…109 g Physical phenomenon Hydration obsidian, glass mm Chemical reactions Racemisation bone, hair 102…106 g Biological growth Lichenometry lichens

Characterization Provenance Biological origin Technology Man Living conditions and Climate

Provenance Heterogeneity of the Earths crust Materials collected from a certain deposit may have a specific composition Mineral (stone, clay), metal, slag, glass

Provenance Flint Provenance of 70 % of flint axes identified by trace elements alone Together with archaeological data, e.g. context and date, 95 % identified

Provenance Garnets

Biological origin Squalene Stigmasterol Cholesterol

Biological origin Chemical analyses of: Fats/Oils Waxes Pitches Tars Leather Textile Food Morphological analyses: Seeds Leather Fur Textile Bone Short-chain fatty acids Long-chain ketones and DAG Long-chain fatty acids and MAG Triacylglycerols (TAG) Sterols Gas chromatogram of lipid residues IR-spectra of organic residues Scanning Electron Micrographs of cells from barley and pea in prehistoric food residue

Technology Deposit or Inlay?

Technology Just because its green doesn't mean its bronze (Stjerna 1997)

Technology Symbols or Cymbals: the Fröslunda shields From a sulfide ore - late Bronze Age Hammered and annealed – not suitable as cymbals Flattening of slag inclusions – hammered from a piece 15 cm in diameter

Man Diet C- and N-isotopes, trace elements Breast-feeding N-isotopes Sex determination Osteology, aDNA Kinship aDNA Migration aDNA, S- and O- isotopes, trace elements

Living conditions and climate Disease Osteology, aDNA Climate O-isotopes Vegetation, regional Pollen analysis Vegetation, local Plant macro fossils, organic geochemistry

Facilities • aDNA laboratory for extraction and PCR, post-PCR laboratory in separate building • Atomic Absorption Spectrophoto-meter for trace metal element analyses of soil, bone and artefacts • Field-archaeology equipment, incl. sampling probes, field spectrophotometer, metal detector, GPS, total station, photo-tower for analogue or digital cameras • Fourier Transform Infrared Spectrometry for analyses of organic residues and pigments • Freezer-room for the storage of very large samples, e.g. whole graves • Gas Chromatography and Mass Spectrometry for organic residue analyses • GIS computer systems for spatial analyses • Mass Spectrometry for isotope (C, N, S, O) analyses primarily of bone collagen • Microscopes and sample preparation equipment for analyses of archaeo-botanical materials, textiles, etc

Scientific Tools for Probing the Past