UKH

I'd always thought Glyder Fawr fell just shy of 1000m but I noticed today it's been elevated to over 1000m.  When did that happen?

Must be global warming

It is the bigger (Fawr) one, thought it always had. But in the 1888 six inch maps "Glyder Mawr" trig is 3,279 feet =999m (rounding down a .4). Same in 1912 and 1953.

Not sure I can be ar5ed to dig out old paper copies (if I have them) to try to see when it got it's extra height, due to the rounding being between whole metres, it only needs another 15cm to make the rounding up to 1,000m 

​​​​​But you're right, it has got a metre taller at some point

At least since the last ice age, and probably long before that (actually about 500 million years or so). Answer to your actual question: it was resurveyed in 2010 with dGPS - it’s actually 1000.8m, round up of course so 1001.

Has Myrddyn Phillips, the oracle of Welsh hill heights been up there with his Trimble?

http://mappingmountains.blogspot.com/?m=1

It was 999m until fairly recently. Just checked the date and apparently it was remeasured in 2010.

It could be the result of isostatic rebound.

Yes, just looked at my OS 1:25,000 map from 2009 and it's shown as 999m so clearly after that.

Probably another Brexit benefit.

it's just a big cairn on the summit

Link here with more details (link to a doc). https://www.hill-bagging.co.uk/mountaindetails.php?qu=S&rf=1967

Thanks all.  Reassuring to know my memory hadn't entirely deserted me !

There was a lot of coverage at the time, including some stupid invention of something called a "super mountain"

https://www.theguardian.com/uk/2010/sep/21/wales-peak-promoted-super-mounta...

It's not. It's surveying precision. Isostatic rebound in the northern UK is single digit millimetres per year.

I blame Hugh Grant

This was way back in 2010. Way before Brexit was a thing. This was delivered at the start of the Cameron Clegg coalition.

Gordon Brown had claimed he'd ended the boom-bust cycle of isostatic rebound and isostatic depression with his superior governance. But the coalition were running scared because Plaid had just gained a seat in Arfon, they had to give something.

The anglicised "Mount Snowdon" was already a sore point (and tall enough already). So the cheapest one to increase to become a 1,000'er was Glyder Fawr and that's what they did...

Slightly off the subject but... with global warming raising sea levels and all mountain heights calculated as being above mean sea level, won't all our hills become lower?

Not off topic at all! "Sea level" is actually somewhat of a misnomer, it's better to just think of it as a zero point - so shouldn't change any elevations of the hills.

Actually, its a little known fact that just like sea water expands as it warm up, so does rock. Hence all mountains will getting slightly bigger as a result of climate change....

Glyder Fach will be next to sneak above 1000m....

That would be 3283' 6".  Saw it in a tunnel.

So if sea levels rise 1 metre, sea level will be 1 metre above sea level? 

Is it that much? That would be enough over a couple of decades.

Is that high or low tide?

Neap or springs?

Bit more I think because the UK's official sea level has been kept under a little trap door in the floor of a concrete hut at the end of a pier in Cornwall since 1921, and sea levels have already risen a bit since then.

https://www.bbc.co.uk/news/science-environment-56935097

All this discussion just washes right over me 

You'll regret ever having asked that

https://www.youtube.com/watch?v=lCA0II1sVZA&t=18s

which he followed with the comment

"One fact I couldn't fit into the video: the Newlyn Datum doesn't change over time. It's based on a brass marker on that harbour wall. Which means that as the actual sea levels rise, the Sea Level won't. [Edit: and I misspelled geodesy as "geodisy"! Apologies to Prof. Clarke.]"

So yes.. sea, level will rise higher than sea level as "sea level" is that brass marker in Cornwall, but then again Cornwall goes up and down 6 or 7 cm with the tides (see video) so the height of hills like Glyder Fawr rises and falls with the Newlyn tides. If any hills are really close to that 1,000m height??  (Glyder Fawr is a pretty safe one) make sure you walk up at the right time of day/tides or you might not be able to tick it off as a 1,000'er

It was an open secret that it was actually over 1000m back when I lived locally in the mid 70's. The 999m height referred to a survey marker (a small metal blob) on the SE side of the summit rock, which was more than a metre lower than the top of the rock.