2 ARCHAEOLOGY Locating Sites The Excavation Investigating the Evidence Dating Methods
3 LOCATING SITES How do we know where to find archaeological sites? Sometimes they are obvious (eg. Colosseum)However, most are found by chance.
4 LOCATING SITES Chance vs Investigation Chance finds are common, lost sites may be exposed by natural elements such as weather, or by human activity such as farming, construction, warfare, fishing, dredging etc.Eg. Pompeii was found when a drain was constructed in late 1500’s.
5 In 1974, workers digging for a village water project in China found some strange pottery items. Their discovery led to the unearthing of the great Terracotta Army.
6 LOCATING SITESInvestigation is actively looking for a site. There are several methods used by archaeologists.Written Documents: old maps, ancient textsScientific Methods: Aerial photography, Surveying, Satellite imagery, Photographic Probes.Trial Trenches: usually 1m by 1m “test” pits across a site.
7 Satellite Imagery of Angkor Wat temple complex, Cambodia
8 EXCAVATION What happens on a dig? The excavation is a process of recovering, collecting and recording information.There are many steps to the process of excavation. Once a site has been located and a decision is made to excavate, the site director selects a team of experts.Some experts used on a dig:CartographerAnthropologistEpigrapherArchitectBotanistNumismatistGeochemistRadiologistClimatologistZoologistPathologistPapyrologist
9 EXCAVATION The Excavation team Title Job Description Director Supervises dig, maintains site records.Assistant DirectorCare and allocation of equipment. Finance.Site SupervisorResponsible for specific section of the site.Labelling of artefacts and recording relevant information.DiggersUnearth items, clear soil from around artefacts.RecordersRecord position of artefacts, enter details in a log.MeasurersRecord location of artefact at the site, measure dimensions.WashersWash artefacts.SiftersSift excavated dirt to locate small finds.PhotographersRecord finds and strata profiles.SurveyorsSurvey the site, draw up layout of site.Lab ExpertsPreserve / repair artefacts.IllustratorsScale drawings of artefacts.
10 EXCAVATION Methods of Excavation: a) Grid Excavation This is where the site is divided into squares of boxes in a given size. Each square is numbered and then excavated leaving a wall (called a baulk) in between.Each baulk provides a vertical record of the layers that have been dug through. The layers are called strata and each one is labelled with everything found in them.
14 EXCAVATION b) Open-area excavation This is where the site is uncovered layer by layer. Different strata are not revealed.
15 EXCAVATION STRATIGRAPHY Generally, a site depends on the principle of Stratigraphy; That each settlement on a site will leave a layer of debris. Normally, the oldest strata will be the deepest.Stratigraphy can become very complex, due to movements of the earths crust and intrusions (such as wells or pits).
18 INVESTIGATING THE EVIDENCE Archaeologists follow three basic stages of investigation.The archaeologist asks question at each stage of the investigation to determine the relevance and reliability of the evidence.
19 OBSERVATION CLASSIFICATION & RECORDING INTERPRETATION Stage 1:OBSERVATIONCollection of information.- Where was it located?- Who used it?- Purpose / function?Stage 2:CLASSIFICATION& RECORDINGPlace objects in correct contextRecord important information.- Is it authentic?- What can be learnt from it?- Does it relate to other evidence?Stage 3:INTERPRETATIONDraw conclusions by looking at the evidence and studying patterns that may emerge.
20 DATING THE PAST Prehistory & History HistoricalTimesPrehistory = before civilisation (writing)History = Since Writing
21 DATING THE PAST Historical Dating The measurement of time Calendars have been used based on natural events, eg. sun and moon, Ancient Egyptians based time on the annual flooding of the Nile.Based on written documents. (After 3500 B.C)Most used is based on Christ’s life. AD (anno Domini,) and BC (Before Christ)
22 DATING THE PAST Relative vs Absolute Dating Methods Relative Dating = Gives a general idea of the time period an artefact comes from. Often dated through chronological sequence (in relation to something else)Absolute Dating = Gives an absolute date in calendar years (also called scientific dating)
23 (Earliest Old Stone Age) Iron Age1,000 BCBronze Age3,000Copper Age5,000Neolithic(New Stone Age)9,000Mesolithic(Middle Stone Age)10,000Upper Palaeolithic(Latest Old Stone Age)The Three Age System:Stone, Bronze, Iron30,000Middle Palaeolithic(Middle Old Stone Age)100,000Lower Palaeolithic(Earliest Old Stone Age)2 Million
24 DATING THE PAST RELATIVE DATING TECHNIQUS TYPE?DESCRIPTION?USES?StratigraphicTypologySeriationThree Age systemThe study of layers in the earth (strata). The oldest is at the bottom.Classifying objects according to their characteristics. Compare scientifically dated objects.The arrangement of artefacts in a chronological sequence.3 stages of technological development by humans – Stone age, Bronze age and Iron Iron age,Grid excavation. Sites where geological change is noted. Inside test pits.Items found in large quantities eg.potteryArtefacts found in large quantities – similar uses to typology datingAnything made by humans out of stone, copper, bronze or iron.
27 DATING THE PAST Absolute Dating Methods 1. Radiocarbon Dating All living things absorb isotope carbon-14 from the atmosphere.At the point of death this process ceases.C-14 begins to decay at a known rate > 5730 years half is decayed (“half life”)By measuring the amount of C-14 left in an organism, scientists can tell when it died, therefore its age.Dates expressed in + or – BP. That means: something could be 2000 years + or – 100 yearsLimit is 50, 000 years.
29 DATING THE PAST Absolute Dating Methods 2. AMS Dating Recent development in radiocarbon datingCan date very small amounts of material containing C-14Will extend radiocarbon dating back to 100,000 yearsFirst absolute dating method used in Rock Art. (pigments of paint from ochre trees or charcoal)
30 DATING THE PAST Absolute Dating Methods 3. Tree-Ring Dating (Dendrochronology)Dates timber objectsCounting the growth rings of a treeMost species ring annually or every two years.Comparing overlapping trees (in age) can reveal a continuous sequence for thousands of years.
32 DATING THE PAST Absolute Dating Methods 4. Thermoluminescence Dating Used to date pottery and clay that has been firedClay gives off radiation. This displaces electrons which become trapped in the structure of the clay.When re-heated, electrons go back to original positions, giving off light. The light is measured to determine age of the clay since firing.Dates to 35,000 years
33 DATING THE PAST Absolute Dating Methods 5. Potassium-Argon Dating Used to date volcanic rockSimilar to radiocarbon datingVolcanic rock contains potassium-40 which converts to argon-40 as it ages.Half life of 1.3 billion yearsUseful in dating fossil remains (human and other) embedded in volcanic rock.
34 Which Dating Method?CHOOSE THE METHOD OF DATING FOR THE FOLLOWING, AND STATE WETHER IT IS A RELATIVE OR ABSOLUTE DATING METHOD.Inscription on a stone wallStone tool from Africa found without any other materialHuman remains found in a tombWooden beam found as part of Viking shipA glass bottle found during an excavationThe Great Pyramid in GizaAboriginal rock art paintingPiece of charred bread from stomach of a bog bodyA group of stone tools varying in styleA collection of pottery from a site in AthensSingle pottery piece from SpartaA bronze axe from ItalyPapyrus paper from Ancient EgyptA fossil of a hominid jaw from East AfricaA coin found at Byblos in LebanonSeed residue from a stone hand axe
35 Research and explain how the following dating methods work Carbon 14 (radiocarbon) datingPotassium – Argon datingDendrochronologyThermoluminescence dating