Excavation Mosul University Archaeology Program Sunday, May 26, 2013 Overview • Excavation has become the primary method of acquiring archaeological data. • Excavation is inherently destructive. Thorough documentation will become the only remaining record of the excavated material. • Materials documented and collected are used as evidence to explain past human behavior and site formation process. Sunday, May 26, 2013 Objectives • In this lecture, you will learn the following elements of archaeological method and theory: – Designing and executing an excavation – Archaeological recording – Analyzing stratigraphic, material, and contextual data Sunday, May 26, 2013 Key Terms • • • • • • Stratigraphic relationships Total excavation Baulk Profile & plan Deposit Feature Sunday, May 26, 2013 WHAT IS EXCAVATION? Sunday, May 26, 2013 Excavation produces data • Archaeological record is a product of behavioral and transformational processes, comprised of the materials within the matrix • Provenience documents the distribution of material within the matrix • Associated materials found in the same deposit are assumed to be archaeologically related • Context is the combined analysis of provenience, association, and matrix • Data produced by the archaeological record are subject to interpretation Photo: Author’s own Sunday, May 26, 2013 Excavation is destructive • Majority of archaeological material is below the surface • Removal of matrix destroys contextual evidence • Documentation is the only record for excavated material • Total excavation (complete removal) is generally avoided, but sometimes necessary Photo: Author’s own Sunday, May 26, 2013 7 Excavation is preservation • Sites facing human and natural threats can be preserved in documentation • Though the archaeological record in its original form, with proper recording it can be studied in the future • But, without site, only documentary evidence can be used to answer future research questions, which can be limiting (no more samples) Photo: Author’s own Sunday, May 26, 2013 8 EXCAVATION PLANNING Sunday, May 26, 2013 Where to excavate? • Locate unexcavated site based on surface evidence – Survey – Remote sensing • Start new project on previously investigated site • Chance find during commercial investigative survey • Rescue of threatened archaeological material Photo: Author’s own Sunday, May 26, 2013 10 Logistics • • • • • Permissions Funding Time Staing Research design – Sampling strategy Photo: Author’s own Sunday, May 26, 2013 11 Logistics: Permissions • Permits – What are the requirements? – Import/export license for finds & sample processing outside country • Laws – National antiquities/historic preservation laws – Ownership of materials – Special treatment of human remains • Private landowners – Permission for excavation – Discuss equipment storage, access, facilities, maintenance, security Photo: Author’s own Sunday, May 26, 2013 12 Logistics: Funding • Understand where your funding originates and the motives behind it • Governmental – Advocacy: promotion of national scientific advancement, investigation of the past – Obligation: expansion of infrastructure or utilities • NGO & University – Advocacy: promotion of select research projects, advancement of method, improving knowledge of a time or place • Commercial – Obligation: agricultural/industrial/housing expansion – Advocacy: promotion of research or past, positive public relations • Private donations – Advocacy: Individual interest, personal cause Photo: Author’s own 13 Sunday, May 26, 2013 Logistics: Time • Research project – Primary purpose is archaeological investigation, instruction – Urgency: low, occasionally medium • Commercial – Identification of cultural resources prior to construction – Urgency: medium • Rescue – Material under immediate threat of destruction – Urgency: high Photo: Author’s own Sunday, May 26, 2013 14 Logistics: Staing • Who is recruited is based on project goals and finances • Professionals – Contractors – Academics • Students – Field school – Graduate students • Specialists • Volunteers Photo: Author’s own Sunday, May 26, 2013 15 Logistics: Research design • Determine: – Purpose • Research, rescue, or commercial investigation? – Time constraint – Funding and budget – Available resources (laboratories, storage, data management) and specialists – Preservation requirements • Design: – Sampling strategy • Excavation units, • Artifact collection methods, • Types of environmental, geological, chemical samples • Absolute dating methods – Investigation goals – Data processing time frame 16 Sunday, May 26, 2013 EXCAVATION PROCESS Sunday, May 26, 2013 Excavation Process • Pre-excavation – Research design – Sampling strategy – Grid layout – Unit placement – Surface clearance – Spoil heap – Facilities organization • Excavation – Digging technique – Seeing stratigraphic changes – Collection methods 18 Sunday, May 26, 2013 Pre-ex: Grid layout and unit placement • Define datum point, then set base line – Base on known geodetic points if available – Measuring from one base line reduces error – Try to use immovable grid points to prevent shifting • Lay out grids – Digitally: EDM or theodolite – Manually: hand tapes (beware of slope to avoid error) • Establish site coordinate system • Place units, cut trenches 19 Photo: Author’s own Sunday, May 26, 2013 Pre-ex: Grid layout Set datum point and baseline, then triangulate rest of grid using tapes B A S E L I N E datum point 20 Sunday, May 26, 2013 Pre-ex: Cutting trenches Photo: Author’s own Sunday, May 26, 2013 21 Pre-ex: Surface clearance • Determine depth of modern surface • If surface truncated or shallow turf, remove manually • Machinery can be used to remove deep modern deposits, concrete surfaces • Once archaeological surface exposed, remove remaining topsoil with sharp trowel strokes Photo: Author’s own Sunday, May 26, 2013 22 Pre-ex: Facilities • Organize the site: – Spoil heaps – Pathways – Recording area • Protected area to store records, supplies, finds/ samples – Rest area • Protected area for breaks, meals, escaping elements – Toilet • Private area, away from site • Maintain cleanliness Photo: Author’s own 23 Sunday, May 26, 2013 Health and Safety: Site maintenance Photo: Author’s own Sunday, May 26, 2013 • Set spoil heap away from trenches • Establish direct barrow paths and walkways • Never sit on trench edges or step on edge to enter/exit unit • Shore up unit walls during deep soundings • Use hard hats and high-visibility jackets • Keep string lines low and visible • Use flagging tape on protruding pegs, nails • Keep a stocked first-aid kit 24 Health and Safety: Personnel care • Communicate! • Know your physical limits • Take frequent breaks • Drink water, eat right • Lift with knees, not back • Wear proper attire, prepare for the elements Photo: Author’s own Sunday, May 26, 2013 Photo: Author’s own Excavation: Dig Tools Pick: to excavate deep passes Spade: to edge units, cut through turf Shovel: to remove large amounts of spoil Barrow: to carry large amounts of spoil Trowel: primary tool, used for everything Leaf: detailed trowel-work Brush: to remove fine particles from solid features • Pan: to remove small amounts of spoil • Sift: to separate • • • • • • • Photo: Author’s own Sunday, May 26, 2013 Excavation: Good digging habits • Work from known to unknown • Move side to side, working backwards • Minimum contact with surface: crouch • Never walk over area just cleaned • Brush stones/surfaces, not soil • Clean up loose often • Communicate! Photo: Author’s own Sunday, May 26, 2013 27 Good habits Crouching Working in one direction Cleaning up loose YES Photo: Author’s own Sunday, May 26, 2013 28 Excavation: Bad digging habits • • • • • • • • Using wrong tools Improper dress Working in circles Ignoring your neighbor Walking over a cleaned area Sitting in trench Smoking in trench Digging without purpose! Be aware Bare feet NO!! Photo: Author’s own Sunday, May 26, 2013 29 Y Bad habits Sitting on unit edge YES NO!! Crouching YES 30 Photo: Author’s own Sunday, May 26, 2013 Bad Habits Digging without purpose NO!! Photo: Author’s own Sunday, May 26, 2013 31 Bad Habits Sitting on surface NO!! Photo: Author’s own Sunday, May 26, 2013 32 Bad habits Using equipment inappropriately NO!! Photo: Author’s own Sunday, May 26, 2013 33 Excavation: Stratigraphic changes Photo: Author’s own • • • • • • • • • Color Texture Compactness Moisture level Inclusions Layer thickness Horizon transition Finds Relationships with other strata 34 Sunday, May 26, 2013 Excavation: Artifact/ecofact collection • Hand collection in trench • Sifting Photos: all Author’s own – Using screen for finds • Flotation – Using water to separate ecofacts and tiny finds from soil • Block lift – Removing a whole find and surrounding matrix in an entire unit when it is too delicate to excavate in the field 35 Sunday, May 26, 2013 Excavation: Sampling • Samples are only as good as the quality of collection • Process in a timely manner • Types: – – – – Geomorphology Carbon Microbotanical Phosphate Photo: T. Parno Sunday, May 26, 2013 36 RECORDING Sunday, May 26, 2013 Recording Methodology • Registers • Photographs • Drawings – Plans – Profiles • Data management – Databases – Geographic Information System Photo: Author’s own 38 Sunday, May 26, 2013 Recording: Registers • Stratigraphy • Features & structures • Artifacts – Batch collection – Small finds • Samples • Photos • Drawings • Basic information: – Stratigraphic context – Location – Elevation – Description – ID of excavator 39 Sunday, May 26, 2013 Recording: Field notebooks • Each excavator should keep a personal notebook • Can keep track of deposits being excavated • Write down changing interpretations • Keep track of levels, drawings, photos Photo: Author’s own Sunday, May 26, 2013 40 Recording: Photographs • More flexible than drawing, can capture a variety of angles, color, texture • Subjective, altered dramatically by light, angle • Uses: – Document context and stratigraphic relationships – In situ finds, features – Demonstrate relationship among diferent excavation units • At very least, take photos at the start of a new layer • Always take photos at end of the day, even when midcontext Photo: Author’s own Sunday, May 26, 2013 41 Recording: Photographs • Film can be used, but digital cameras more popular, easier, and less expensive to process • Method: – Clean area, spray if contexts are diicult to see – Remove non-archaeological material – Place scales along features – Place N arrow in correct direction – Reduce shadow – Get elevated – Take both color and B&W – Bracket exposure (-1, 0, +1) – Use wide-angle lens if available – Document day, direction, contexts, features, photographer in register Sunday, May 26, 2013 Photo: T.Fowler 42 Recording: Photography Photo: T.Parno Sunday, May 26, 2013 43 Recording: Spatial record • Horizontal and vertical position of features and finds • Documented with depths and triangulation, manually with tapes or digitally with EDM, etc. • Visually represented in plans and profiles Photo: MF Lane 2011 44 Photo: Author’s own Sunday, May 26, 2013 Recording: Drawings • Plan: horizontal space • Profile: vertical space • Not artistic, but subject to archaeological interpretation of drawer • Better than photos for defining limits contexts Photo: Author’s own Sunday, May 26, 2013 45 Drawing: Plan • Used to document distribution of contexts, features, finds • Drawn after removal of each context • Typically 1:20 scale Photo: Author’s own 46 Sunday, May 26, 2013 Drawing: Plan • Method: – String measuring tape from base line – Mark unit edges – Use plumb-bob with tapes or planning frame to locate and draw contexts, features, finds; make sure tapes/frame are level – Label with corresponding recording numbers – Take elevations, mark on plan Photo: Author’s own 47 Sunday, May 26, 2013 Drawing: Plan Lay tape and string from base line Place planning frame along tape Photo: Author’s own Sunday, May 26, 2013 48 Drawing: Plan Place planning frame on each meter mark. Each string marks 20 cm plumb bob Use plumb bob to follow the feature. tape planning frame Use strings as guide. Draw what’s inside each box. 20cm 1m 49 Sunday, May 26, 2013 Drawing: Plan Image: T.Parno Sunday, May 26, 2013 50 Drawing: Profiles • Used to document stratigraphy • Subject is trench wall or bisected feature baulk • Plot all profiles on plans • Typically 1:10 scale Photo: Author’s own Sunday, May 26, 2013 51 Drawing: Profiles • Method: – Set two stakes at each end of section – Tie string between stakes and then level – Secure measuring tape under string, also level – Measure distance from string to top and bottom of layer to determine depth, repeat across section face – Constantly check string line is taut and level – Determine elevation of string to provide depths of layers Take elevation on string when finished Measure distance from string to stratum Sunday, May 26, 2013 Leveled string 52 Image:: adapted from WikiCommons Drawing: Profile Image: T.Parno Sunday, May 26, 2013 53 Matrix description • Color – Munsell chart • Sediment grain size – Clay, silt, sand • Inclusions – Stones (size, shape) – Charcoal (flecks, fragments, pieces) Photos: all Author’s own Sunday, May 26, 2013 54 Feature description • Always consider relationship between matrix and feature • Cuts and Infilled features – Ditches, post holes • Structures/architecture – How do elements fit together? – Stone, brick, timber • Burials Photo: all Author’s own – Record and photo in situ 55 Sunday, May 26, 2013 Recording: Data management Image: A.McCreery • Computers – Storage of all recorded data • Databases – Images – Artifacts – Samples • Geographic Information System (GIS) Image: AROURA Project Sunday, May 26, 2013 – Finds recording – Elevations – Photos 56 Evidence analysis • Consider deposits, finds, and stratigraphic relationships for each context AND the unit as a whole • Should be an evolving process • Constantly reevaluate original theories • Look at other trenches • Discuss with other excavators Photo: Author’s own 57 Sunday, May 26, 2013 Conclusions • Archaeology is inherently destructive, but can produce new data for future study • Take into account the logistics and evaluate available resources and personnel when developing a research design prior to excavation • Recording evidence is the most important aspect of excavation Sunday, May 26, 2013 Further Reading • T. Hester, H. Schaffer, K. Feder (2009) Field Methods and Archaeology. Walnut Creek: Left Coast Press. • B.A. Kipfer (2006) Archaeologist’s Fieldwork Companion. London: Blackwell. • S.Roskams (2001) Excavation. Cambridge: Cambridge University Press. • C. Renfrew and P. Baun (2012) Archaeology: Theories, Methods, and Practice. London: Thames & Hudson. 59 Sunday, May 26, 2013