Plate techtonics

[+Eclectic Penguin]

Sorry if this has been brought up before but I got thinking while chatting with a friend the other day...

 

How long before a published coordinate is seriously compromised by the shifting of the continental plates on the earth's surface?

 

I'm sure that this is a thought experiment rather than a practical issue - but plates do shift and over the millennia and various parts of the UK have been in very different locations on the globe in the past - and not necessarily at the same time either!

Edited April 21, 2008 by Eclectic Penguin

[+The Blorenges]

...but plates do shift and over the millennia and various parts of the UK have been in very different locations on the globe...

 

Excellent! I needed a plausible excuse for a couple of recent DNFs

 

MrsB

[+MartyBartfast]

How long before a published coordinate is seriously compromised by the shifting of the continental plates on the earth's surface?

 

I'm pretty certain that we'll all be dead an buried (& out children & our childrens children) before it becomes a problem so I ain't gonna worry about it.

[+Renegade Knight]

Looks like someone has taken time to do a presentation on this very issue.

 

http://www.naref.org/transf/nad83_hydroscan2006.pdf

 

Quick and dirty.

NAD83 seems to be tied to the ground.

WGS84 is tied to a speroid that's independant of the ground.

 

It would appear that it would take an earthquake to make much of a difference. California when it has the "big one" for example. Plate techtonics is too slow otherwise.

Edited April 21, 2008 by Renegade Knight

[+PopUpPirate]

Heck that's hardcore. I still don't know the answer to the following :

 

If a cacher can't find a micro in a forest and no one is around to see them, is it still a DNF?

 

[+Eclectic Penguin]

Wow - pretty heavy stuff for what I thought would be thought experiment already!

 

I guess it shows that others have thought the same thing that I had - and also that scientists are debating it too - which is a good thing!

[+Eclectic Penguin]

So, If I understand this correctly, WGS84, being independent of the ground means that the ground is shifting under our feet because of continental drift as far as Geocaching coordinates are concerned then, however slow that's happening.

 

I too have wanted to use continental drift as an excuse for a DNF []

[+careygang]

So is this a serious project, or just caching without the McTrash

 

geodrift

[+Happy Humphrey]

I wondered about this very subject when finding Point Reyes Earthquake Trail a while ago. I guess they didn't want to use a container due to the guidelines banning "travelling caches".

[NickPick]

The UK is on the Eurasian plate, which is (If I recall correctly) moving south-east at a rate of about 1 cm per year. This is about the speed at which your fingernails grow.

 

It was 7 years ago when I did that training course, and I didn't look it up, so I might not be 100% on the exact direction and rate.

[+Simply Paul]

There are parts of the world moving much faster due to the effects of plate movement. I'm thinking of vertically more than horizontally. Several islands and mountains have appeared within a few short years...

[+Alibags]

There are three types of plate boundary; divergent, such as the boundary along the middle of the Atlantic, where the plates are moving apart (and new crust is being formed at the boundary);convergent, such as where the Indian plate has bashed into the Eurasian plate causing a few folds (the Himilayas) and transform, where the plates are moving laterally to one another, for example along the San Andreas fault in California. The rate of movement is very very slow, apart from where friction causes the plates to stick, and then the pressure builds up until they slip and move very rapidly indeed (ie an earthquake).

 

I don't think you can get away with using this as an excuse for a DNF, unless of course the cache falls into a large crack caused by an earthquake, or is suddenly thrust up onto the top of new island formed by a volcano (but if this is a very remote island, Simply Paul will have an event there presently!).

[+The Blorenges]

...if this is a very remote island, Simply Paul will have an event there presently!.

 

MrsB

[+macroderma]

So is this a serious project, or just caching without the McTrash

 

geodrift

 

I bumped into this one today while looking for something else

 

Anyone know of any background?

 

I thought it is an easy, interesting and worthwhile add-on to some of my caches that are in good GPS reception areas

[+kbootb]

The UK is on the Eurasian plate, which is (If I recall correctly) moving south-east at a rate of about 1 cm per year. This is about the speed at which your fingernails grow.

 

It was 7 years ago when I did that training course, and I didn't look it up, so I might not be 100% on the exact direction and rate.

I've got the same figure and analogy somewhere, but I'm sure my fingernails grow more than 1 cm a year.

 

But assume the 1 cm/year figure is about right. = 1 m in 100 years. The best I ever get is about 10m 'accuracy' on my GPS. So about 1000 years before plate drift moves a point outside the 'circle of uncertainty'.

[+Bear and Ragged]

So is this a serious project, or just caching without the McTrash

 

geodrift

 

I bumped into this one today while looking for something else

 

Anyone know of any background?

 

I thought it is an easy, interesting and worthwhile add-on to some of my caches that are in good GPS reception areas

 

A couple of Trigs around Warwick/Leamington have a small (35mm film tub) cache placed near them and a link to the geodrift site