Magnetic North

[Janne]

As best I remember the weight of glacial ice on a tectonic plate is as minuscule as the weight of an ice chest on cruise ship.

If you measure, the chest will depress the ship a fraction into the water.
The tectonic plates are between 20 and 200 kilometres thick, an ice layer of 3 kilometres thickness will add anything from a huge % weight increase to one that is quite small.
As the tectonic plate under Scandinavia is around 60 km ( 10 to 100 km) , a 3 km layer is a significant weight increase!

https://www.ngu.no/en/topic/why-are-there-mountains-norway

 

[Janne]

https://doi.org/10.1098/rsif.2019.0295

Will they get confused and get off course?

 

[Robson Valley]

The rock of all the tectonic plates is a little bit plastic. Plastic on a geological scale = they can be deformed.
North of North Dakota in Saskatchewan, find the capital city of Regina. The next 100 miles north, including Last Mountain Lake,
is rising maybe 4" per year since being relieved of the ice load.

 

[Janne]

That is a lot. Plate must be thin?

 

[Robson Valley]

Even if the best guess is that the ice sheet was no more than 1 km thick, it covered most of Canada. That's a HUGE weight.
As sea levels dropped as much as 100m, Doggerland must have been a marvelously rich landscape to live in.

I'm not at all impressed with the voicings of panic about the rapid shifting of the North Magnetic Pole.
This isn't like flicking off a light switch. Open your compass, reset the declination and move on.

 

[Janne]

They estimate that Fenno Scandia had 3 km thickness, thinning out further south and over UK. around 1km over UK.

They trawl up loads of finds from the North Sea banks. Sometimes even fish!

 

[Tengu]

Isostasy?

Dont ask me, I slept though that lecture.

Here in Cornwall we have raised beaches...and drowned forests...

 

[EdS]

Even more of rarity 31 December some of us will be able to see in 2020....

 

[Janne]

Isostasy?

Dont ask me, I slept though that lecture.

Here in Cornwall we have raised beaches...and drowned forests...

Isostasy is the floating balance of something that floats on top ?
The crust level with ice cap was on one isostatic level, fully in balance and harmony considering, then when the ice melted it had to balance out to a new level. That process is still going on.

( I did not sleep through Geology, but it was many, many moons ago, so I might have a wrong /false memory there)

I assume the raised beaches are from an earlier geological era when Cornwall was either covered with sea, or prime beachfront, and the drowned forests are from recent times, when the Ice caps locked in the water, and sea lever was 100-150 meters lower than today?

 

[Woody girl]

They reckon that the pole shift has sped up over the last few years and is now moving at 55km per year. They had to update things a year earlier than predicted so that navigation by planes and ships and satellites etc could stay on track. Back at the beginning of last century it was only moving a few miles a year. Barely noticeable in the great scheme of things. Nowadays it's moving realy fast. We are in a solar minimum and so earth's magnetic features are more erratic anyway. What does concern me is that we are more vulnerable to solar radiation and space weather hitting the planet. This can cause a multitude of problems with tectonic plates volcanoes earthquake and weather... to say nothing of emp's.
I think we could be in for some rough times in the future. .. providing we survive brexit!

 

[Janne]

I am a 'half full glass ' type of guy...
Think of the spectacular Aurora Borealis' you might enjoy in UK!

 

[petrochemicals]

As best I remember the weight of glacial ice on a tectonic plate is as minuscule as the weight of an ice chest on cruise ship.

I think it's more like putting arabbit at one end of a canoe, may make little difference, only on inch, which is a good thing really, any more and we would be knackered

 

[Janne]

You have a pet rabbit, or is he Emergency Food?
(Or a combination - children’s pet, and if Brexit happens, emergency food?)

 

[petrochemicals]

Was thinking food, could have been fish or duck really.

Talking of pet rabbit, my fatherat the factory he worked at once had someone offer a pet rabbit, yes says this fellow and picks it up. A few weeks later one asks the other " how's the rabbit" "delicious" reply the other