GENIZA FRAGMENTS 70: The October 2015 issue of the Newsletter of the Taylor-Schechter Genizah Research Unit, Cambridge University Library has a number of interesting articles, notably "Palimpsests? There’s more than meets the eye..." by Melonie Schmierer-Lee. A palimpsest is a manuscript whose original writing has been erased and over-written with a new text. Careful scrutiny, these days often with the help of technology, can allow scholars to recover the erased text.
On a related note, AWOL pointed to the following earlier this month: Galen Syriac Palimpsest Digital Release at OPENN. More on that manuscript is here.
Some other posts on various palimpsests are here, here, here, here, and here. And this post discusses a forged palimpsest manuscript from the nineteenth century.