Zac Miller can’t be certain exactly how long Timber Ridge Cemetery has been in use, but he is sure of one thing: It holds the keys to a treasure trove of local history. Miller, a lecturer of geographic information science at the University of North Georgia’s Gainesville campus, said the northeast Hall County cemetery dates at least to the early 19th century, and includes burial sites of Civil War and possibly Revolutionary War veterans. Miller said it is among the oldest cemeteries in the county.