I agree with Jerry that archives aren't generally in the business of preserving their contents against every possible contingency, such as nuclear war or other civilization destroying events. We plan the for the future as practically as we can. That's hard enough. Mechanical and digital storage have their advantages and disadvantages. Both need to be "migrated" regularly to preserve access and data integrity (shellac discs may be the longest lasting medium we know of so far, but they're still not permanent). But digital preservation files have the distinct advantage of being able to be monitored and re-preserved (converted to new file formats and/or moved around storage locations) automatically with little or no loss of data. Of course the means to monitor and migrate data must be part of any serious digital preservation plan, but this seems to widely recognized now. 20 year-old computers and their data are difficult to salvage because migration plans did not exist. Several years ago at LC, I saw someone from the Church of Scientology demonstrate their long-term preservation medium for L. Ron Hubbard's lectures. It was a conventional disc made of some special of non-oxidizing alloy, vacuum-sealed in a special sleeve. The person claimed that these discs should last for thousands of years, and if I recall correctly, the disc format was chosen specifically because of the ease of retrieval by other civilizations, domestic or alien. As far as I know this is the only example of an archive seriously looking to a post-"civilization" era and acting on a solution. James Conjecture about preserving data for archaeologists or alien visitors is amusing but not very applicable. Any archival media should be evaluated every "few" years to detect any degradation and to allow a copy to be made if any risk is detected. Transfer to media using updated technology should be anticipated every 20 years or so. Material that is centuries, or even decades, old can be expected to be severely degraded, as is now being discovered with film. Material that is thousands of years old usually contains very limited information, digitally equivalent to a few bytes, not GB, and its limited visual content must be painstakingly reconstructed. In context, information can be carved into granite, cast into titanium, or whatever you like. Such efforts can only preserve very limited amounts of information (cave drawings anyone), and lingual or pictoral content would probably be just as difficult to interpret eons hence as coded digital data would be. Jerry Media Sciences, Inc.