Reference Mark Keychain

Replica of the early flat topped reference mark introduced by the US Coast & Geodetic Survey in 1913. This mark had a flat top, with a thick stem with a thin slit and small tabs on the underside of the disk. The disk text made reference to the the Superintendent of the Coast & Geodetic Survey. This style of mark was in common use until a domed top reference mark was introduced in 1921. Other changes introduced was a change in the text referencing the Director of the Coast and Geodetic Survey as well as a different style of stem.