Excavation Techniques Excavation Techniques and Analysisand Analysis

Applications to Applications to

PaleoanthropologyPaleoanthropology

About Excavation and AnalysisAbout Excavation and Analysis

Authors’ definition:Authors’ definition: Study of past cultures analyzing material Study of past cultures analyzing material

remains of human behaviorremains of human behavior Study entailsStudy entails Time: Date of the site and its contentsTime: Date of the site and its contents Space: Location of the site and its contentsSpace: Location of the site and its contents Material remains: siting, retrieval, analysis Material remains: siting, retrieval, analysis

Fundamentals of Excavation and Fundamentals of Excavation and AnalysisAnalysis

Site discovery and selectionSite discovery and selection Excavation of artifacts, ecofacts, and featuresExcavation of artifacts, ecofacts, and features Analysis for dates, attributes, and environmentAnalysis for dates, attributes, and environment

An Example: Flow Chart for Combe An Example: Flow Chart for Combe Capelle Capelle (A Neanderthal Site) (A Neanderthal Site)

Research DesignResearch Design DiscoveryDiscovery PreparationPreparation Data Collection (The Dig)Data Collection (The Dig) AnalysisAnalysis Interpretation/SynthesisInterpretation/Synthesis

Some DefinitionsSome Definitions

Ecofacts: remains of plants, animals, sediments, Ecofacts: remains of plants, animals, sediments, or other materials not modified by human or other materials not modified by human activity activity

Features: immovable structures, pits, posts, Features: immovable structures, pits, posts, burial sitesburial sites

Artifacts: all portable objects altered by human Artifacts: all portable objects altered by human activityactivity

Sites: Landscape where human activity took Sites: Landscape where human activity took place, as indicated by the aboveplace, as indicated by the above

How are Sites Formed?How are Sites Formed?

Taphonomy: Study of how lifeforms or Taphonomy: Study of how lifeforms or artifacts wound up at a particular locationartifacts wound up at a particular location

Primary refuse: items left at site of usePrimary refuse: items left at site of use Secondary refuse: Items moved elsewhereSecondary refuse: Items moved elsewhere

How are Items Preserved? How are Items Preserved? Material Material

Some materials resist deterioration:Some materials resist deterioration: Bone: Skulls and teethBone: Skulls and teeth Stone or Metal (tools, ornaments)Stone or Metal (tools, ornaments) Seeds, with protective coversSeeds, with protective covers

How Are Objects Preserved? How Are Objects Preserved? EnvironmentEnvironment

Arid climates (Peruvian coast)Arid climates (Peruvian coast) Water: Planks at Ozette, WA or FranceWater: Planks at Ozette, WA or France Peat moss: the “Bog People” in ScandinaviaPeat moss: the “Bog People” in Scandinavia Ice: Ötzi the “Iceman” in Austrian/Italian AlpsIce: Ötzi the “Iceman” in Austrian/Italian Alps Volcanic Ash, Cerén, El SalvadorVolcanic Ash, Cerén, El Salvador

Site DiscoverySite Discovery

Lucky findsLucky finds Consulting available sources: studies, records, Consulting available sources: studies, records,

even older informantseven older informants Maps and aerial photographsMaps and aerial photographs Geographical Information Systems/Remote Geographical Information Systems/Remote

SensingSensing

Site SelectionSite Selection

Learning everything possible about each siteLearning everything possible about each site Selecting as large and representative a site as Selecting as large and representative a site as

possiblepossible Preliminary work: surface finds, features, Preliminary work: surface finds, features,

perhaps test pits or trenchesperhaps test pits or trenches Problem-Oriented Research and Deliberate Problem-Oriented Research and Deliberate

SurveysSurveys

Survey: Mapping, Part 1: Survey: Mapping, Part 1: General General

First principle: Digging is destructive--record First principle: Digging is destructive--record everything!everything!

MappingMapping Latitude, longitude, and elevationLatitude, longitude, and elevation Benchmarks or featuresBenchmarks or features MeasurementsMeasurements Horizontal Horizontal VerticalVertical

Surveying: Mapping Part 2: Surveying: Mapping Part 2: Horizontal MeasurementHorizontal Measurement

Select and draw west-east (X-axis) Select and draw west-east (X-axis) and north-south (Y-axis) baselines and north-south (Y-axis) baselines from from primary site datum primary site datum

Mark off intervals at meters and Mark off intervals at meters and centimeters from baselinescentimeters from baselines

Label the intervals along axes of Label the intervals along axes of the grid by letters, numbers, or boththe grid by letters, numbers, or both

Adapt procedure according to Adapt procedure according to topographical or archaeological topographical or archaeological featuresfeatures

Laying Out an Alternative GridLaying Out an Alternative Grid

Survey: Mapping Part 3: Survey: Mapping Part 3: Vertical MeasurementsVertical Measurements

Surveying using transit or alidade and Surveying using transit or alidade and measuring rodmeasuring rod

Vertical base: benchmark or permanent feature Vertical base: benchmark or permanent feature of known elevationof known elevation

Convert measures to meters above sea level.Convert measures to meters above sea level.

Example: Work In ProgressExample: Work In Progress

Virtual Dig: Virtual Dig: Mapping in Combe-Mapping in Combe-CapelleCapelle

Retraced excavation by Henri-Marc AmiRetraced excavation by Henri-Marc Ami Excavated sample squares of the site Excavated sample squares of the site Squares distinguished bySquares distinguished by Letter (X axis)Letter (X axis) Numbers (Y axis)Numbers (Y axis) Vertical measurements by 4 strata.Vertical measurements by 4 strata.

Survey: Test pits and trenchesSurvey: Test pits and trenches

Test pits provide sample of site stratigraphyTest pits provide sample of site stratigraphy Stratigraphy: Stratigraphy: profile of two or more layers ofprofile of two or more layers of Natural sedimentNatural sediment Human depositsHuman deposits Test pits provide sample of overall siteTest pits provide sample of overall site Several pits suggest which part should be Several pits suggest which part should be

excavated most extensivelyexcavated most extensively

Survey: Test PitsSurvey: Test Pits

Advantages: Provide preliminary information Advantages: Provide preliminary information on siteon site

DisadvantagesDisadvantages Need more pits to round out informationNeed more pits to round out information May not yield full stratigraphyMay not yield full stratigraphy

Survey: TrenchesSurvey: Trenches

UsesUses Provide full stratigraphyProvide full stratigraphy Provide sample of artifacts to establish chronologyProvide sample of artifacts to establish chronology Locate featuresLocate features Find site boundariesFind site boundaries TypesTypes Slit trenchesSlit trenches Step trenchesStep trenches Backhoe trenchesBackhoe trenches Wall trenchesWall trenches

Survey: Trenches—Advantages and Survey: Trenches—Advantages and DrawbacksDrawbacks

Advantages: Advantages: Good samples of artifactsGood samples of artifacts Find buried featuresFind buried features Good time depthGood time depth DrawbacksDrawbacks Destructive, especially with backhoeDestructive, especially with backhoe Can destroy potential activity areas before knowing Can destroy potential activity areas before knowing

what’s therewhat’s there Danger of collapseDanger of collapse

Deciding Where to ExcavateDeciding Where to Excavate

Sampling depends on research questionsSampling depends on research questions Judgmental Sampling: based on prior Judgmental Sampling: based on prior

knowledge of site; used at Combe-Capelleknowledge of site; used at Combe-Capelle Probabilistic SamplingProbabilistic Sampling Random samplingRandom sampling Stratified sampling: based on prior knowledgeStratified sampling: based on prior knowledge Known trash deposits or architectural featuresKnown trash deposits or architectural features Ensure everything significant is includedEnsure everything significant is included

Tools for ExcavationTools for Excavation

Dental picks or paint brushesDental picks or paint brushes Ice picksIce picks Tweezers (fragile objects)Tweezers (fragile objects) Trowels (pointed and square)Trowels (pointed and square) Shovels (pointed and square-nosed)Shovels (pointed and square-nosed) Heavy equipment (backhoes)Heavy equipment (backhoes) Buckets and ScreensBuckets and Screens

Tools Used for Rough ExcavationTools Used for Rough Excavation

Shovel, Round Nose Club HammerShovel, Round Nose Club Hammer Pick Chisel, FlatPick Chisel, Flat Pry Bar Scraper, Long HandlePry Bar Scraper, Long Handle Sledge HammerSledge Hammer

Tools Used for Fine ExcavationTools Used for Fine Excavation

Top row:Top row: plastic paint trowel, rubber air puffer, large brushes, plastic paint trowel, rubber air puffer, large brushes, small brush, wooden/plastic sculpting tools/small paint small brush, wooden/plastic sculpting tools/small paint trowel), plastic spoon trowel), plastic spoon Bottom row:Bottom row: note pad, folding ruler (in cm.), Marshalltown note pad, folding ruler (in cm.), Marshalltown trowel (45-5), 8"mill bastard file, plastic spoon, plastic trowel, trowel (45-5), 8"mill bastard file, plastic spoon, plastic trowel, tape measure (3-4 m. is sufficient) tape measure (3-4 m. is sufficient)

Vertical Excavation: Some “Laws”Vertical Excavation: Some “Laws”

Law of Association:Law of Association: Artifacts found at the same stratum (layer) are in Artifacts found at the same stratum (layer) are in

association with one anotherassociation with one another Artifacts found at different strata are not in Artifacts found at different strata are not in

association with one anotherassociation with one another Law of Superposition: Geological layers are stratified Law of Superposition: Geological layers are stratified

one upon anotherone upon another Lower strata are older than higher onesLower strata are older than higher ones Uniformitarianism: Geological processes similar Uniformitarianism: Geological processes similar

throughout timethroughout time

The “Laws” IllustratedThe “Laws” Illustrated

a) Law of Association: Skeleton, dagger, and burial pit are at a) Law of Association: Skeleton, dagger, and burial pit are at the same levelthe same level

b) Law of Superposition: pot is at the higher stratum andb) Law of Superposition: pot is at the higher stratum and stone axe is at the lower stratumstone axe is at the lower stratum

Vertical Excavation: Vertical Excavation: StratigraphyStratigraphy

Layer deposited in chronological order: lowest Layer deposited in chronological order: lowest layer is oldest and so on.layer is oldest and so on.

Disturbances can change stratigraphyDisturbances can change stratigraphy Erosion from hillside: oldest is top layerErosion from hillside: oldest is top layer Structure foundation disturbs layersStructure foundation disturbs layers Burrowing animals may move objectsBurrowing animals may move objects Then there are golddiggers and pothuntersThen there are golddiggers and pothunters

Vertical Excavation: Procedure: Vertical Excavation: Procedure:

Each artifact is recorded and removedEach artifact is recorded and removed Photographed, sketched, or describedPhotographed, sketched, or described Vertical and horizontal positionVertical and horizontal position Soils analyzed for chemistry, pollen, etcSoils analyzed for chemistry, pollen, etc Associations between artifacts are recordedAssociations between artifacts are recorded Assumption: artifacts found at same layer Assumption: artifacts found at same layer

occurred at same time periodoccurred at same time period

Vertical Excavation: ProveniencingVertical Excavation: Proveniencing

Definition: recording artifacts in three-Definition: recording artifacts in three-dimensional spacedimensional space

Transit and stadia rod: record is set from a Transit and stadia rod: record is set from a secondary datum pointsecondary datum point

Theolodite: Records the position of a artifact Theolodite: Records the position of a artifact Using both vertical and horizontal coordinatesUsing both vertical and horizontal coordinates

What is a Theolodite?What is a Theolodite?

Left: Front View Right: Back ViewLeft: Front View Right: Back View Front Lens Viewing Lens and FocusFront Lens Viewing Lens and Focus Gun Sights Adjustment knobs (v and h)Gun Sights Adjustment knobs (v and h)

Laser TheoloditeLaser Theolodite

Adds an electronic distance meter (EDM)Adds an electronic distance meter (EDM) And a laser device to the theoloditeAnd a laser device to the theolodite It records the position of an artifactIt records the position of an artifact Using a laser bouncing off a prism of known heightUsing a laser bouncing off a prism of known height Results can be written down or linked to a portable Results can be written down or linked to a portable

computercomputer Printer can produce tags that are detachedPrinter can produce tags that are detached And put with the artifact to be photographed before And put with the artifact to be photographed before

removalremoval

Horizontal Excavation: Horizontal Excavation: ProcedureProcedure

As each layer or stratum is excavated, it is As each layer or stratum is excavated, it is removedremoved

Same procedure of excavation is repeated for Same procedure of excavation is repeated for next layernext layer

One or two layers: prefer horizontal excavation One or two layers: prefer horizontal excavation to get lay of the siteto get lay of the site

Different samples are taken for different layers: Different samples are taken for different layers: soil, pollen, charcoal, bonesoil, pollen, charcoal, bone

Some layers may be left for controlSome layers may be left for control

Overview of DatingOverview of Dating

UnifomitarianismUnifomitarianism Relative DatingRelative Dating

StratigraphyStratigraphy AssociationAssociation

Absolute DatingAbsolute Dating CalendricalCalendrical Natural FeaturesNatural Features IsotopicIsotopic

Dating: UniformitarianismDating: Uniformitarianism

Uniformitarianism vs. CatastrophismUniformitarianism vs. Catastrophism Uniformitarianism: All geological processes--Uniformitarianism: All geological processes--

erosion, weathering--observable today have erosion, weathering--observable today have always been present and at the same ratealways been present and at the same rate

Uniformitarianism is the basis of dating.Uniformitarianism is the basis of dating. Catastrophism: Changes have been sudden and Catastrophism: Changes have been sudden and

have occurred at different rates in the past have occurred at different rates in the past from those of the present.from those of the present.

Relative DatingRelative Dating

Stratigraphy: Stratigraphy: Establishment of sequences by Establishment of sequences by soil stratasoil strata Exceptions: soil disturbance, erosion.Exceptions: soil disturbance, erosion.

Law of Association: Dating of finds within a Law of Association: Dating of finds within a stratumstratum

Chronometric AssociationsChronometric Associations

Basic principle:Basic principle: Materials associated with Materials associated with other materials of known age are the same age other materials of known age are the same age rangerange Bottle styles and clay pipes .Bottle styles and clay pipes . Gravestones in Stoneham, MA (Deetz)Gravestones in Stoneham, MA (Deetz)

Absolute Dating: CalendricalAbsolute Dating: Calendrical

Entails use of traditional calendarsEntails use of traditional calendars MayanMayan

Long Count:Long Count: Beginning date fixed at 3113 BC Beginning date fixed at 3113 BC Calendar Rounds: Calendar Rounds: 260- and 365-day calendars260- and 365-day calendars

Egyptians: Egyptians: 332 BC Conquest by Alexander the Great332 BC Conquest by Alexander the Great Traced back through recorded dynastiesTraced back through recorded dynasties Astronomical events checked by present data Astronomical events checked by present data

Others: Others: Chinese, Romans, GreeksChinese, Romans, Greeks

Absolute Dating: Natural Absolute Dating: Natural FeaturesFeatures

Dendrochronology: Dendrochronology: Tree ring datingTree ring dating Tree rings vary from year to yearTree rings vary from year to year Local stumps or timber compared with master Local stumps or timber compared with master

sequence (e.g., Univ. of Arizona)sequence (e.g., Univ. of Arizona) Varve analysis: Varve analysis: Clay deposits in lakes from Clay deposits in lakes from

melting ice.melting ice. Patterns also differ yearlyPatterns also differ yearly Likewise compared with master chart.Likewise compared with master chart.

Absolute Dating: Isotopic or Absolute Dating: Isotopic or Radiometric TechniquesRadiometric Techniques

Common PrinciplesCommon Principles Isotopes: Isotopes: Radioactive variants of elements (e.g. Radioactive variants of elements (e.g.

carbon, potassium)carbon, potassium) Isotopes decay from radioactive to nonradioactive Isotopes decay from radioactive to nonradioactive

element element They do so at a constant rateThey do so at a constant rate

Half Life: Half Life: The period in which radioactivity The period in which radioactivity rate reaches half the original rate.rate reaches half the original rate.

Isotopic Techniques: Radiocarbon Isotopic Techniques: Radiocarbon DatingDating

Carbon Carbon is found in all lifeformsis found in all lifeforms Carbon 12Carbon 12 is the stable element is the stable element All living things accumulate All living things accumulate Carbon 14Carbon 14 At death, carbon 14 decays at a constant rate to At death, carbon 14 decays at a constant rate to

Carbon 12Carbon 12 It reaches half the rate of original radioactivity in It reaches half the rate of original radioactivity in

5730 years5730 years At 11460 years, radioactivity is half the second At 11460 years, radioactivity is half the second

rate--and so onrate--and so on

Isotopic Techniques: Accelerator Isotopic Techniques: Accelerator Mass SpectrometryMass Spectrometry

In dating, a sample is cleaned then burned to In dating, a sample is cleaned then burned to produce gasproduce gas

Proportion of C14 to C12 is then counted Proportion of C14 to C12 is then counted using Geiger counterusing Geiger counter

Several grams are required for the countSeveral grams are required for the count Accelerated Mass Spectrometer: Accelerated Mass Spectrometer: counts counts

individual moleculesindividual molecules Advantage: High accuracy, less materialAdvantage: High accuracy, less material

Isotopic Techniques: Isotopic Techniques: Radiopotassium DatingRadiopotassium Dating

Half life: Half life: 1.3 billion years1.3 billion years Potassium is found in granite, basalt, clayPotassium is found in granite, basalt, clay Potassium 40 decays to a gas, Argon 40Potassium 40 decays to a gas, Argon 40 Argon 40 accumulate when a rock is formedArgon 40 accumulate when a rock is formed Disadvantage: materials less than 500,000 Disadvantage: materials less than 500,000

years old cannot be datedyears old cannot be dated

Other Absolute Dating TechniquesOther Absolute Dating Techniques

Electronic Spin Resonance:Electronic Spin Resonance: Accumulation of unpaired electrons in crystals in tooth Accumulation of unpaired electrons in crystals in tooth

enamel and other items with calcium (inaccurate in enamel and other items with calcium (inaccurate in bone)bone)

Geomagnetism: Geomagnetism: Alignment of particles on magnetic rock; this is Alignment of particles on magnetic rock; this is

approximate and there are few labsapproximate and there are few labs Obsidian Hydration:Obsidian Hydration:

Reaction with water; measured by thickness of Reaction with water; measured by thickness of accretion.accretion.

Conclusion: DatingConclusion: Dating

All techniques are problematicAll techniques are problematic Appropriate labs may be rareAppropriate labs may be rare Analyzable material must be present: no volcanic Analyzable material must be present: no volcanic

rock, no radiopotassium datesrock, no radiopotassium dates Inherent problems: radiocarbon dating may be off Inherent problems: radiocarbon dating may be off

by centuriesby centuries Best strategy: use several techniquesBest strategy: use several techniques

e.g. dendrochronology with radiocarbon.e.g. dendrochronology with radiocarbon.

ConclusionConclusion

All excavation involves destructionAll excavation involves destruction Therefore, sites have to beTherefore, sites have to be Excavated carefully, often with trowelsExcavated carefully, often with trowels Recorded for location and elevationRecorded for location and elevation Artifacts catalogued before removalArtifacts catalogued before removal Features have to be mappedFeatures have to be mapped Ideal: Sites could be reconstructed Ideal: Sites could be reconstructed Based on recording of dataBased on recording of data