30 October 2012
The latest benchmark comes to you courtesy of Rick Le Mon, who’s an undergraduate tackling a challenging schedule and a senior thesis! He offers up a National Geodetic Survey gravity control marker on Antelope Island in Utah:
Antelope Island is the largest of the 11 islands in Utah’s Great Salt Lake, and actually becomes a peninsula when water in the lake is low. It’s located in the southern part of the lake, is a Utah State Park, and is home (since 1993) to antelope, as well as its own herd of bison.
Gravity survey markers are used by the National Geodetic Survey as base stations to make measurements of the acceleration of gravity at different points around the country; this data is then used to compute the state of the Earth’s geoid (the equipotential surface of the gravity field). This model gets used to do things like accurately determine elevations, for geophysical exploration, and even for weights and measures laboratories.