I wonder if instead we could encode this information in a metal that does not corrode, like gold. Unfortunately gold is also a precious metal. Silver or copper are good candidates too. The transcription of data could be done with a laser in microprint. The data could also be encoded similar to how we encode dvds but instead of just etching a tiny mark a partial hole could be punched half way through for every ON bit. This way the data would be less susceptible to scratches. Make the disc 1 centimeter thick and the holes .5 centimeters deep. This way it would take a lot to destroy the data. A simple scratch would not do it. Anybody with a microscope and the knowledge of binary would be able to decode this. The instructions could be printed on the other side in microprint That could be read with a microscope.

Books and scientific journals could be the first to be encoded. Reputable newspapers could be next. Maybe the entire library of congress. Social media data can be encoded dead last or not at all since it would not help in rebuilding a civilization. We do not need to encode every tweet.