Archaeological excavation
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In archaeology, excavation is the exposure, processing and recording of archaeological remains.[1] An excavation site or "dig" is the area being studied. These locations range from one to several areas at a time during a project and can be conducted over a few weeks to several years.
Excavation involves the recovery of several types of data from a site. This data includes
Before excavating, the presence or absence of archaeological remains can often be suggested by, non-intrusive
During excavation, archaeologists often use stratigraphic excavation to remove phases of the site one layer at a time. This keeps the timeline of the material remains consistent with one another.[7] This is done usually though mechanical means where artifacts can be spot dated and the soil processed through methods such as mechanical sieving or water flotation. Afterwards, digital methods are then used record the excavation process and its results. Ideally, data from the excavation should suffice to reconstruct the site completely in three-dimensional space.
History
The first instance of archaeological excavation took place in the sixth century BC when Nabonidus, the king of Babylon, excavated a temple floor that was thousands of years old.[8] During early Roman periods, Julius Caesar's men looted bronze artifacts, and by the medieval period, Europeans had begun digging up pots that had partially emerged from erosion, and weapons that had turned up on farmlands.[8] Antiquarians excavated burial mounds in North America and North-West Europe, which sometimes involved destroying artifacts and their context, losing information about subjects from the past. Meticulous and methodical archaeological excavation took over from antiquarian barrow-digging around the early to mid-nineteenth century and is still being perfected today.[9][8]
The most dramatic change that occurred over time is the amount of recording and care taken to ensure preservation of artifacts and features.[citation needed] In the past, archaeological excavation involved random digging to unearth artifacts. Exact locations of artifacts were not recorded, and measurements were not taken. Modern archaeological excavation has evolved to include removal of thin layers of sediment sequentially and recording of measurements about artifacts' locations in a site.[citation needed]
Motivation
There are two basic types of modern archaeological excavation:
- Research excavation – when time and resources are available to excavate the site fully and at a leisurely pace. These are now almost exclusively the preserve of academics or private societies who can muster enough volunteer labour and funds. The size of the excavation can also be decided by the director as it goes on.
- Development-led excavation – undertaken by professional archaeologists when the site is threatened by building development.[10] This is normally funded by the developer, meaning that time pressure is present, as well as its being focused only on areas to be affected by building.[10] The workforce involved is generally more skilled, however, and pre-development excavations also provide a comprehensive record of the areas investigated. Rescue archaeology is sometimes thought of as a separate type of excavation but in practice tends to be a similar form of development-led practice. Various new forms of excavation terminology have appeared in recent years such as Strip map and sample some of which have been criticized within the profession as jargon created to cover up for falling standards of practice.
Development-led archaeology
There are two main types of trial excavation in professional archaeology both commonly associated with development-led excavation: the test pit or trench and the watching brief. The purpose of trial excavations is to determine the extent and characteristics of archaeological potential in a given area before extensive excavation work is undertaken. This is usually conducted in development-led excavations as part of Project management planning. The main difference between Trial trenching and watching briefs is that trial trenches are actively dug for the purpose of revealing archaeological potential[11] whereas watching briefs are cursory examination of trenches where the primary function of the trench is something other than archaeology, for example a trench cut for a gas pipe in a road. In the US, a method of evaluation called a Shovel test pit is used which is a specified half meter square line of trial trenches dug by hand.
Concepts
Site formation
Archaeological material tends to accumulate in events. A gardener swept a pile of soil into a corner, laid a gravel path or planted a bush in a hole. A builder built a wall and back-filled the trench. Years later, someone built a pigsty onto it and drained the pigsty into the nettle patch. Later still, the original wall blew over and so on. Each event, which may have taken a short or long time to accomplish, leaves a
The prominent processual archaeologist Lewis Binford highlighted the fact that the archaeological evidence left at a site may not be entirely indicative of the historical events that actually took place there. Using an ethnoarchaeological comparison, he looked at how hunters amongst the Nunamiut Iñupiat of north central Alaska spent a great deal of time in a certain area simply waiting for prey to arrive there, and that during this period, they undertook other tasks to pass the time, such as the carving of various objects, including a wooden mould for a mask, a horn spoon and an ivory needle, as well as repairing a skin pouch and a pair of caribou skin socks. Binford notes that all of these activities would have left evidence in the archaeological record, but that none of them would provide evidence for the primary reason that the hunters were in the area; to wait for prey. As he remarked, waiting for animals to hunt "represented 24% of the total man-hours of activity recorded; yet there is no recognisable archaeological consequences of this behaviour. No tools left on the site were used, and there were no immediate material "byproducts" of the "primary" activity. All of the other activities conducted at the site were essentially boredom reducers."[12]
Stratification
In archaeology, especially in excavating,
By separating a site into these basic, discrete units, archaeologists are able to create a chronology for activity on a site and describe and interpret it. Stratigraphic relationships are the relationships created between contexts in time representing the chronological order they were created. An example would be a ditch and the back-fill of said ditch. The relationship of "the fill" context to the ditch "cut" context is "the fill" occurred later in the sequence, i.e., you have to dig a ditch first before you can back-fill it.[17] A relationship that is later in the sequence is sometimes referred to as "higher" in the sequence and a relationship that is earlier "lower" though the term higher or lower does not itself imply a context needs to be physically higher or lower. It is more useful to think of this higher or lower term as it relates to the contexts position in a Harris matrix, which is a two-dimensional representation of a site's formation in space and time.
Understanding a site in modern archaeology is a process of grouping single contexts together in ever larger groups by virtue of their relationships. The terminology of these larger clusters varies depending on practitioner, but the terms interface, sub-group, group and land use are common. An example of a sub-group could be the three contexts that make up a burial: the grave cut, the body and the back-filled earth on top of the body. In turn sub-groups can be clustered together with other sub-groups by virtue of their stratigraphic relationship to form groups which in turn form "
Phasing
An "intrusion" or "intrusive object" is something that arrived later to the phase in the strata, for example modern pipework or the 16th-century bottles left by treasure-hunters at Sutton Hoo.
Methods
Excavation initially involves the removal of any topsoil. A strategy for sampling the contexts and features is formulated which may involve total excavation of each feature or only portions.
Stratigraphic excavation
In stratigraphic excavation, the goal is to remove some or, preferably, all archaeological deposits and features in the reverse order they were created and construct a Harris matrix as a chronological record or "sequence" of the site.[14] This Harris matrix is used for interpretation and combining contexts into ever larger units of understanding. This stratigraphic removal of the site is crucial for understanding the chronology of events on site.
Stratigraphic excavation involves a process of cleaning or "troweling back" the surface of the site and isolating contexts and edges which are definable as either:
- Discrete, discernible "edges" that are formed by being completely separated from the surrounding surface and therefore stratigraphically later than its surroundings
- Discrete, discernible "edges" (as in 1.) and have boundaries dictated by the limit of excavation[18]
Following this preliminary process of defining the context, it is then recorded and removed. Often, owing to practical considerations or error, the process of defining the edges of contexts is not followed and contexts are removed out of sequence and un-stratigraphically. This is called "digging out of phase". It is not good practice. After removing a context or if practical a set of contexts such as the case would be for features, the "isolate and dig" procedure is repeated until no man made remains are left on site and the site is reduced to
Tools and techniques
Mechanical excavation
This describes the use in excavations of various types and sizes of machines from small
Recording
Archaeological excavation is an unrepeatable process, since the same area of the ground cannot be excavated twice.[23] Thus, archaeology is often known as a destructive science, where you must destroy the original evidence in order to make observations. To mitigate this, highly accurate and precise digital methods can be used to record the excavation process and its results.[24]
Single context recording system
Digital recording
Digital tools used by field archaeologists during excavation include
Finds processing
Finds and artifacts that survive in the archaeological record are retrieved in the main by hand and observation as the context they survive in is excavated. Several other techniques are available depending on suitability and time constraints. Sieving (screening) and
Flotation
Flotation is a process of retrieval that works by passing spoil onto the surface of water and separating finds that float from the spoil which sinks. This is especially suited to the recovery of environmental data stored in organic material such as seeds and small bones.[25] Not all finds retrieval is done during excavation and some, especially flotation, may take place post-excavation from samples taken during excavation.
Sieving
The use of sieving (screening) is more common on research-based excavations where more time is available. Some success has been achieved with the use of cement mixers and bulk sieving. This method allows the quick removal of context by shovel and mattock yet allows for a high retrieval rate. Spoil is shoveled into cement mixers and water added to form a slurry which is then poured through a large screen mesh. The speed of this technique is offset by the damage it does to more fragile artifacts.
Spot Dating
One important role of finds retrieval during excavation is the role of specialists to provide
See also
- Archaeological field survey
- Archaeological plan
- Archaeological section
- Cut (archaeology)
- Feature (archaeology)
- Forensic archaeology
- Relationship (archaeology)
- Spit (archaeology)
References
- ^ "What Is Excavation?". Archaeological Excavations in Greece. 13 April 2012. Retrieved 9 July 2020.
- ^ Emery, Katy Meyers (4 October 2011). "Archaeology 101: Artifact versus Feature". MSU Campus Archaeology Program. Retrieved 21 July 2020.
- OCLC 821067667.
- ^ Kelly&Thomas (2011). Archaeology: down to earth (4th ed.). Belmont, Calif.: Wadsworth, Cengage Learning.
- OCLC 50802481.
- S2CID 164041261
- ^ ISBN 978-0-19-965743-8.
- ^ ISBN 978-0-19-965743-8.
- ^ "Archaeology". Encyclopedia Britannica. Retrieved 13 July 2020.
- ^ a b "Learning Archaeology: Excavation: Choosing a Site: Development Led Excavation". www.pastperfect.org.uk. Archived from the original on 25 September 2020. Retrieved 21 July 2020.
- ^ "What is Test Pit Excavation for Soil Evaluation and what is Its Purpose?". Metro Pits. 27 July 2017.
- ^ Binford, Lewis (1978). "Dimensional analysis of behaviour & site structure: learning from an Eskimo hunting stand". American Antiquity. 40: 335.
- ^ Brock, Terry (16 February 2010). "Archaeology 101: Reading Stratigraphy". MSU Campus Archaeology Program. Retrieved 21 July 2020.
- ^ )
- ^ "Dating Techniques In Archaeology". www.archaeologyexpert.co.uk. Retrieved 29 July 2020.
- ^ a b "Glossary". Archaeological Institute of America. Retrieved 29 July 2020.
- ^ "Learning Archaeology: Excavation: Recording: Stratigraphy: Cut / Fills". www.pastperfect.org.uk. Retrieved 29 July 2020.
- ^ "Stratigraphic Excavation". Archaeology Skills Passport. 14 June 2014. Retrieved 31 July 2020.
- .
- ^ "How to dig?". Past Perfect. Retrieved 4 September 2013.
- ^ "PBS' Time Team America to Debut July 8 with Dig on Roanoke Island". First Colony Foundation. Archived from the original on 17 October 2013. Retrieved 10 October 2013.
- ISBN 978-1861978806.
- ISBN 978-0713427387.
- S2CID 109818432.
- ^ "What is Archaeological Flotation?". Zagora Archaeological Project. 6 September 2019. Retrieved 29 July 2020.
- Barker, Philip (1993) Techniques of archaeological excavation, 3rd ed., London : Batsford, ISBN 0-7134-7169-7
- Westman, Andrew (Ed.) (1994) Archaeological site manual, 3rd. ed., London : Museum of London, ISBN 0-904818-40-3
Further reading
- Corrado Pedeli and Stefano Pulga (2013). Conservation Practices on Archaeological Excavations: Principles and Methods, Los Angeles: Getty Publications, ISBN 978-1-60606-158-9
- ISBN 978-1-60606-124-4
External links
- Adrian Chadwick – Archaeology at the Edge of Chaos: Further Towards Reflexive Excavation Methodologies
- Principles of Archaeological Stratigraphy and Practices of Archaeological Stratigraphy as authorised free PDF
- Reuben Thorpe – Which way is up? Context formation and transformation: The life and deaths of a hot bath in Beirut
- Record Checking Guidance for Anglo-Lebanese Excavations in Beirut
- Site Phasing and Higher order grouping guidelines for Anglo-Lebanese Excavations in Beirut
- Hammer, F. – Post Excavation Manual
- NIOSH Safety and Health Topic: Trenching and Excavation.
- Excavations at the Roman city of Sanisera, Menorca, Spain