What is a USGS
Geodetic control points
are permanently affixed objects at various locations all
over the United States to enable land surveying, civil
engineering and mapping to be done efficiently. These
objects are usually metal disks, but can be any other object
that serves as a control point.
Although not as popular
as finding Geo Caches, Benchmark hunting can be very interesting
to try and locate. The databases are mostly pre-GPS
waypoints done with surveyors. They can be way off the
GPS settings which make them hard to find but rewarding
when you do locate them.
The oldest ones I have
found were from 1926 and looked brand new. In other
parts of the country they can go back to the