Principles of excavations
Why can all excavation be described as destruction? Because once the material has been removed it cannot be replaced as it was before the excavation.
How does preservation by record limit the impactt of excavation? Achaeologists must pay appropriate care & attention to the way excavation is carried out & quality records kept.
What 9 points are achaeologists expected to consider before they excavate?
1.Provide justification for digging
2.Use surveying techniques to plan excavation strategies
3.Adjust to subsequent changes on site
4.Put a complete recording system in place
5.Select and maintain appropriate samples for analysis
6.Have facilities for all aspects of post excavation work
7.Interpret a site from a limited excavation or sample
8.Publish the results of the work so they are avaliable to other interested parties
9.Maintain professional standards while working under time and economic constraints
Types of excavation
What is research excavation? On sites that are not under any immediate threat of destruction. sites are selected on thie suitabliity to answer the question they wish to answer.
How are these funded? Both publically and commercially or by universities as 'training excavations'.
What are rescue excavations? Rapid recordings of a site before the site is built.
What is an impact assessment? They establish the nature and extent of the archaeological deposits, they then discuss with contractors on how to aviod cost and delays in construction.
Give an example of a 'mitigation strategy'? A full excavation of a watching brief.
Types of excavations cont.
What is preservation in situ ?
This involves building whilst trying to minimise the damage to the archaeology.
What is a watching brief?
The archaeologist will watch the machines to see if any archaeological remains are unearthed.
What key differences are there between rescue and research achraeology?
Research archaeologists select thier sites, Rescue archaeology has sometimes resulted in many tiny 'keyhole' excavations in to parts of sites rather than full scale excavations of the whole site.
Excavation strategies (Test Pits)
Which 2 key elements do all sites have in common? A vertical sequence & Horizontal layout
Why are these 2 elements so important? They establish a sequence and give a plan on the site
what is a trench? A rectangular shaped pit of variable width, depth and shape
What is a test pit/sondage? 1m X 1m square trench
What is the purpose of a test pit? To evaluate stratigraphy of the site & get excavations samples
What is the vertical profile of a site? Provides info on depth, complexity and cintext of the deposits
How can systematic sampling of vertical profiles help establish the horizontal plan of a site? They give a profile across the whole site at regular intervals
What is area or open stripping? The most common form - it occurs where the extent of the features to be uncovered determines the size of the excavation
What doesn't area or open-stripping mean? That the whole site is laid bare
Why is area excavation so useful?
1.Complete structures can be studied
2.Complex relationships between features can be clarified
3.Provides excellent recording possibilities
4.Total understanding of horizontal relationships is possible
What is the criticism of area excavation?
The sides of trenches have the advantage of revealing the vertical sequence of deposits
How is this criticism overcome?
1. Leaving baulks (undug strips of land)
2. Carefully recording the horizontal pictures of a side layer by layer
If no baulks are left, how can data be checked?
No check is left in place if the director wishes to refer back. So recording systems must be of the highest quality.
Box-grid / Quadrant systems
What is the box grid system? positions between trenches & are of excavation
The 3 advantages of this method?
1. Chance to record sections of every box
2. Removal of waste is easy due to baulks
3. Gives both a horizontal & vertical view of excavation sections
The 4 disadvantages of this method?
1. The whole layout of this site is not revealed until baulks are removed
2.relationships between artefacts & features are not understood whilst digging
3. takes alot of time and man power
4. No use on sites with deep stratigraphy
Box grid cont.
What is the quadrant method?
Feature is cut into four sections by lines intersecting at the middle opposing quadrants are excavated first.
What is the advantage of this method?
1. After removing half of the remains, patterns are evident
2. Records a vertical profile of the site
Why are some sites unsuitable for using the quadrant method?
1. lack of clear stratification
2. Comprises of soil rather than stone & building material
How does the planum method solve this problem? plane off a predermined thickness of deposits across the whole site record results & then repeat process, In effect slices are removed across the site to reveal & record a series of images like an MRI scan.
Which type of site is this useful for? Large open sites with few features
How can the planum method be enhanced? building the deposits veritcally for more precise excavation