Interesting little article for you all to look at.

[Hobbo]

Found this article you might like to read.  Some people might not like it being on the Torygraph, but there are worse news sources out there!

It's about a group of men who re-measured a hill (Thack Moor) and got it reclassified as a mountain.  Another one asking to be walked up, then :-)

http://www.telegraph.co.uk/earth/earthnews/10017758/Three-ramblers-go-up-a-hill-and-come-down-a-mountain.html

[captain paranoia]

I hope they remembered to subtract the length of the pole...

It's quite an interesting example of GPS surveying.  Since the vertical accuracy of GNSS is poor, what they must have done is to record the raw data from the GPS, and then use data from the ten reference stations to apply post-hoc correction of the data, allowing them to get the 2cm accuracy.

I wonder how long it will be before the little bit of grass and moss is worn away by the 2cm required to hit the 200ft mark...

[Pete McK]

I read somewhere that the surface of the earth moves relative to its centre by up to 10 metres in any one day, due to the gravitational pull of the sun, moon and stars. If this is so, and it sounds plausible, how can these guys get an accuracy of 20mm?

[Lyle Brotherton]

According to the US NOAA (National Oceanic and Atmospheric Administration) this tidal pull can except a change of 21 feet (6.4m) but of course all the land mass around you is going to move as well and across the entire width of the earth, so relatively it does not move - think my logic is right 

[MoonMan]

The Moon & Earth share a Barycentre, or Centre of Gravity. the Tides are one manifestation of the Bulge Effect, while, the not-so-noticeable shift in the landscape is another. Not unlike the deck of a ship at sea. Nice to know that some of the ranges around here are, in fact, mountains.