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What is Digital Archiving?#

Archaeology is in a special position with respect to archiving because the act of data creation, e.g. archaeological excavation, results in the destruction of the primary archaeological evidence itself. Increasingly, the digital record may be the only source of precious research materials. It is essential, therefore, that the digital records that describe archaeological resources be made accessible and that their preservation be ensured. Providing for the accessibility of archaeological data and its long-term preservation are the goal of digital archiving.

Digital archiving is different from traditional archiving. Traditional archiving practice seeks to preserve physical objects (e.g. artefacts, samples, paper, photographs, microfilm) that carry information. Digital archiving seeks to preserve the information regardless of the media on which that information is stored. Computer disks and other magnetic and optical media degrade and the information once on them is lost unless it has been moved to other media.  Software and hardware change rapidly: the physical media on which digital data are stored are impermanent.  Other methods are necessary to ensure wide access to and long-term preservation of digital data. 

The Newham Archive: A Case Study of the Loss of Digital Data#

This problem has been effectively demonstrated through work to rescue the contents of the Newham Museum Archaeological Service digital archive. The Archaeological Service was closed down in 1998 and, although its physical collections are still curated by the London boroughs of Newham, Redbridge and Waltham Forest, the digital archive was passed to the ADS. The digital archive represented all the work that was digitised during Newham Archaeological Service fieldwork and post-excavation analysis, along with project designs over a period of about ten years. This archive was delivered to the ADS on 230 floppy disks containing over 6000 files and totalling over 130Mb of data. Much of the data was held in archaic formats or in proprietary software and significant time and effort were required to rescue these files. Unfortunately around 10-15% of the files are still inaccessible and the data that they contain are effectively lost. An additional problem was that the archive was inadequately documented and it was often difficult to reconstruct which files went with which project. As a result there are a number of 'orphaned' datasets, including a large cemetery database, which have been rescued but have little re-use potential.

The Newham Museum Archaeological Service digital archive had two main problems:

  1. data held in non-preservation file formats, i.e. proprietary file formats that have gone out of use
  2. non-existent data or project documentation

The Newham digital archive is probably typical of the digital information resources of archaeological units. There are many archaeology units with archives of files in redundant formats, without explicit information relating them to sites, containing unexplained coding and in unknown states of completion (cf. Condron et al. 1999). These files may also be stored on unsuitable media in poor storage conditions. In short, there may be large amounts of 'archived' archaeological information which can never be accessed again.

The Newham Museum Service digital archive is a depressing and salutary tale. It developed as a working tool to help the Service write up and manage its archaeological projects and, in this respect, the archive was fit for its original purpose. The concept of digital project archiving was still in its infancy when the Newham archive developed. As there were then no published strategies or methodologies to ensure the effective preservation of the data, the poor condition of the Newham archive is understandable.

These Guides have been developed to offer preservation strategies for archaeological project data as it is clear that the road to long-term preservation begins not at the end of a project but at its inception.

The Goals of Digital Archiving#

The overall goals of digital archiving are simple:

  • Through actions and use of appropriate methods and techniques, permit the easy and wide access to digital archaeological data for cultural, educational, and scientific purposes.
  • Through actions and appropriate methods and techniques, ensure the long-term preservation of digital data so that it remains accessible for appropriate uses in the future.

The Principles of Archiving Digital Data#

This section presents an overview of the key issues that should be considered when creating a digital archive.

  • Ensure that existing digital datasets are safeguarded and, where possible, deposited in an appropriate digital archive.
  • When creating new digital archives they should conform to existing standards and guidelines on how data should be structured, preserved and accessed (cf. Managing Digital Collections)
  • All digital archives should ideally be deposited in a digital archiving facility or collections repository where they can be properly accessed, curated, and maintained for the future and, where appropriate, be made available online.
  • The key to successful digital archiving is thorough documentation of the data, how they were collected, what standards were used to describe them and how they have been managed since collection.
  • If there are concerns that some data (e.g., specific site location information) needs to be kept confidential, a means of easily separating these data from non-confidential data must be developed for reporting, analytical data sets, displaying site locations on maps. It is also key that this process is documented and deposited as part of the archive.
  • There is generally no need to preserve interim versions of final digital files. Exceptions to this include interim datasets where either data or text is subsequently discraded or decimated to final publication. These issues are discussed in the later section on Preservation Intervention Points (link to PIPs)
  • Data already held safely in paper archives does not need to be digitised, except to provide a digital security copy or online access to the data. When digitising or scanning from paper records, do not automatically discard the paper originals when complete. Offer them to relevant documentary archives.
  • Although the digital, paper and finds archives may be dispersed, the integrity of the complete archive must be ensured by cross-referencing between collections and signposting on the Internet.
  • In addition to the data itself, documentation is essential for digital preservation, all digital project archives must have three components: data, data documentation (metadata), and data management documentation.
In accordance with the principles presented above, digital archives should at least provide an index to archaeological sites, finds and paper archives and at best provide access to digital records of data, material, documentation, interpretation and analyses.

It is recommended that the collection or creation of digital datasets should be planned at the outset of a project and incorporated into project specifications. It is recognised that funding agencies must acknowledge such requirements if widespread implementation is ever to be achieved.