Rare books and manuscripts appraiser Martin Gammon examines a map that the owner’s great grandfather, a 49er (miner in the 1800s), used to prospect for gold in this video produced for ANTIQUES ROADSHOW. The early rendition of the Britton and Rey map depicts, more accurately than others of its time, the border region between California with what was called Utah, now Nevada. Very few of the maps survived because they were generally carried in the pockets of miners.