Editing Archaeological excavation (section)

==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 [[Archaeological context|context]]. This layer cake of events is often referred to as the [[archaeological sequence]] or [[archaeological record|record]]. It is by analysis of this sequence or record that excavation is intended to permit interpretation, which should lead to discussion and understanding.

The prominent [[processual archaeology|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 [[ethnoarchaeology|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."<ref>Binford, Lewis (1978). "Dimensional analysis of behaviour & site structure: learning from an Eskimo hunting stand". ''American Antiquity''. 40: 335.</ref>

=== Stratification ===
[[File:1555 - Keramikos archaeological area, Athens - Stratigraphy - Photo by Giovanni Dall'Orto, Nov 12 2009.jpg|thumb|upright=1.25|[[Stratigraphy]] in the excavation area in the [[Kerameikos]] Cemetery ([[Athens]]).]]
[[File:Archäologie schichtengrabung.jpg|thumb|Stratification at an excavation site in [[Augsburg]], [[Germany]]]]
{{Main|Stratigraphy (archaeology)}}
In archaeology, especially in excavating, [[Stratigraphy (archaeology)|stratigraphy]] involves the study of how deposits occurs layer by layer.<ref name=":4">{{Cite book|last=Bahn|first=Paul|url=http://veryshortintroductions.com/view/10.1093/actrade/9780199657438.001.0001/actrade-9780199657438|title=Archaeology: A Very Short Introduction|date=2012-08-01|publisher=Oxford University Press|isbn=978-0-19-965743-8|pages=18|doi=10.1093/actrade/9780199657438.001.0001}}</ref> It is largely based on the [[Law of Superposition]]. The Law of Superposition indicates that layers of sediment further down will contain older artifacts than layers above.<ref>{{cite web |last1=Brock |first1=Terry |title=Archaeology 101: Reading Stratigraphy |url=http://campusarch.msu.edu/?p=334 |website=MSU Campus Archaeology Program |date=16 February 2010 |access-date=21 July 2020}}</ref> When archaeological finds are below the surface of the ground (as is most commonly the case), the identification of the context of each find is vital to enable the archaeologist to draw conclusions about the site and the nature and date of its occupation. It is the archaeologist's role to attempt to discover what contexts exist and how they came to be created.<ref name=":2">{{Cite book|last=Ashmore |first=Wendy |url=https://www.worldcat.org/oclc/821067667|title=Discovering our past : a brief introduction to archaeology|others=Sharer, Robert J.|date=4 March 2013 |isbn=978-0-07-803491-6|edition=Sixth |location=New York |oclc=821067667}}</ref> Archaeological stratification or sequence is the dynamic superimposition of single units of stratigraphy or contexts.<ref>{{Cite web|title=Dating Techniques In Archaeology|url=http://www.archaeologyexpert.co.uk/ArchaeologicalDating.html|access-date=2020-07-29|website=www.archaeologyexpert.co.uk}}</ref> The '''context''' (physical location) of a discovery can be of major significance. Archaeological context refers to where an artifact or feature was found as well as what the artifact or feature was located near.<ref name=":3" /> Context is important for determining how long ago the artifact or feature was in use as well as what its function may have been.<ref name=":3">{{Cite web|title=Glossary|url=https://www.archaeological.org/programs/educators/introduction-to-archaeology/glossary/|access-date=2020-07-29|website=Archaeological Institute of America}}</ref> The cutting of a pit or ditch in the past is a context, whilst the material filling it will be another. Multiple fills seen in [[Archaeological section|section]] would mean multiple contexts. Structural features, natural deposits and [[inhumation]]s are also contexts.

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 [[Relationship (archaeology)|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.<ref>{{Cite web|title=Learning Archaeology: Excavation: Recording: Stratigraphy: Cut / Fills|url=http://www.pastperfect.org.uk/archaeology/cutsandfills.html|access-date=2020-07-29|website=www.pastperfect.org.uk}}</ref> 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 "[[Archaeological phase|phases]]". A sub-group burial could cluster with other sub-group burials to form a cemetery or burial group which in turn could be clustered with a building such as church to produce a "phase." A less rigorously defined combination of one or more contexts is sometimes called a [[Feature (archaeology)|feature]].

===Phasing===
[[File:Roman horse.png|thumb|upright|[[Horse]] burial in Roman [[ditch]] on a development funded site in London. Note "out of phase" pipe intrusion left in for practical reasons]]
[[File:Romano celtic temple004.png|thumb|upright|Excavation in phase has reduced this site to the occupation level of a [[Celtic polytheism|Romano-Celtic]] temple (56 [[Gresham Street]], [[London]])]]
[[Phase (archaeology)|Phase]] is the most easily understood grouping for the layman as it implies a near contemporaneous [[Archaeological horizon]] representing "what you would see if you went back to a specific point in time". Often but not always a phase implies the identification of an occupation surface "old ground level" that existed at some earlier time.
The production of phase interpretations is one of the first goals of stratigraphic interpretation and excavation. Digging "in phase" is not quite the same as phasing a site. Phasing a site represents reducing the site either in excavation or [[Post excavation|post-excavation]] to contemporaneous horizons whereas "digging in phase" is the process of stratigraphic removal of archaeological remains so as not to remove contexts that are earlier in time "lower in the sequence" '''before''' other contexts that have a latter physical stratigraphic relationship to them as defined by the [[law of superposition]]. The process of interpretation in practice will have a bearing on excavation strategies on site so "phasing" a site is actively pursued during excavation where at all possible and is considered good practice.

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]].