The idea that the Earth continents are moving has been mentionned during the XIXe century (by A. von Humboldt, among others), and formalized by A. Wegener in the early XXe. Now, it is not "just" an idea with indirect proofs such as the continents'contours fitting together, but something measured daily and continuously by a number of instruments all over Earth.

Doris, among other system has been doing such a monitoring for the past 27 years, and is continuing. Doris has about fifty stations all over Earth, used to track satellites on their orbits (mostly altimetry satellites, which embarked a Doris instrument for all of them since 2002 and since 1992 for the T/P-Jason series). It is fully part of the International Terrestrial Reference Frame system, which is providing precise georeferencing to all systems in need of it -- GPS, etc.

Doris will be launched on the next Sentinel-3 (B, C & D), some of the next HY-2 (C, D and E), Jason-CS / Sentinel-6 (A & B), and of course SWOT. The system should thus continues on in the next decades and more