If land is surveyed from ocean shoreline (high-tide). How is it figured years later when tides have changed?

Meaning, does the constant change in the oceans shoreline (over time) effect land suveys and measurements for mountain altitudes?

If land is surveyed from ocean shoreline (high-tide). How is it figured years later when tides have changed?
The other answer is correct to the extent of how surveyors determine boundaries of a plot of land, but is not correct as to how elevation is determined.





Elevation is in fact determined using a datum based on sea level and the current elevation datum for North America is the NAVD 88 (North America Vertical Datum 1988) which is based on a sea level measurement at the mouth of the St. Lawrence River in Quebec, and is carried across the continent from one benchmark to another.





Many benchmarks are considered unreliable in relation to elevation, and correcting them is an ongoing effort. Most purchasers of land are unconcerned about the elevation so this rarely arises in real estate transactions, but is very important to cartographers and for applications like airport and harbor navigation, national flood insurance, precision irrigation for agriculture, ground water monitoring and environmental clean-up, and systems like major sewage and water infrastructure.
Reply:Land surveyors start with a "point with honor", some landmark that doesn't change, like a known corner of a landgrant, an existing point in a nearby survey marked with a metal pin, or something else that can be found by any other land surveyor. From there the surveyor produces a vector, the direction and distance to the point of beginning of the tract of interest. That way, it doesn't matter if one of the boundaries is affected by a change in a nearby waterway, whether an ocean front or a riverbed whose coursees may change . . . the starting point will still indicate the location on the globe where the subject tract was so that it can be located, even it ends up underwater in the future.

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