"[Copper Printing Plate] Ohio. United States Department of the Interior. Geological Survey.", U.S. Geographical Survey
Period: 1890-1920 (circa)
Publication: Department of the Interior
8 x 8.5 inches
20.3 x 21.6 cm
This is a copper plate printing plate produced for the Department of the Interior. Mounted on nearly 1" thick hardwood this plate was obviously strongly built for a large printing run. The plate is about 1/8" thick and permanently attached to the supporting hardwood block, with the number 9246 on one side and the verso blank save for evidence of printer's ink. The surface of the map is etched in a pattern suggesting this is one plate for the chromozylography process. Areas not included in the printing show signs of machine work to remove copper. Copper plates used for printing maps are extremely rare as the copper was usually recycled as the map image became obsolete.