Islands

mckeonj · 140108. Mon Jan 29, 2007 4:31 pm

I feel a klaxon coming on: something to do with map projections and apparent areas.

Gaazy · 140120. Mon Jan 29, 2007 5:20 pm

I still don't get it. What is this about Greenland's girlfriend?

I bet it's some youth culture thing that's above my head, grumble, mumble, grouch...

Lucwhostalking · 140121. Mon Jan 29, 2007 5:27 pm

Gaazy · 140125. Mon Jan 29, 2007 5:44 pm

Oh, RIGHT!!

I must remember to buy something for my atrophy of the brain.

Gaazy · 140213. Tue Jan 30, 2007 3:27 am

Actually, having thought about it, it is a generational thing.

In my day, you were single until you were married, whether or not you were courting/going out (as it was then called), or even engaged to be married.

I wonder, though, whether I'd have got the joke if Archie had written 'No, Greenland's married'.

suze · 140292. Tue Jan 30, 2007 6:47 am

Coming back to the topic if we may, costean raises some good points.

Let us for the moment accept the notion that Greenland is actually three islands overlain by an ice sheet. Given what we are told about the location of this "superfjord", I'd agree that the chances are that the northernmost of the three is in itself larger than New Guinea and hence the largest island in the world. Now as noted by Mr McKeon, standard map projections make Greenland appear larger than it - so guessing by looking at a map isn't really the way to go, but surely some geologist types have come up with approximate sizes for the three islands. Perhaps they could get in touch.

But is the "Greenland is three islands" argument a specious one? Interesting as the three island notion is, Greenland appears to us to be one island because of the presence of the ice sheet. And as costean notes, the weight of the ice has caused the earth's crust to sink downwards in the Greenland region. If the ice were not there, one would have to imagine that the crust would come back up - and might this perhaps cause the three islands to become one?

This site certainly thinks so.

djgordy · 140317. Tue Jan 30, 2007 7:52 am

Greenland is quite interesting from the global warming perspective as discussed on another thread. When the Vikings colonised Greenland in the late 10th century AD, this was during the medieval warm period and it was possible to establish relatively prosperous colonies there supporting around 3,000 people.

http://www2.sunysuffolk.edu/mandias/lia/vikings_during_mwp.html

However, from the 12th century onwards the climate became colder and living conditions became much less favourable.

http://www2.sunysuffolk.edu/mandias/lia/end_of_vikings_greenland.html

costean · 140321. Tue Jan 30, 2007 7:58 am

Very good points Suze. Leaving aside the question of projections of size on maps for the moment, we have to consider what constitutes a landmass. At the moment Greenland is comprised of an ice sheet sitting on bedrock, some/much of which is below sea level. If the ice were not there ie if it melted then the underlying bedrock would rise by a process known as glacial rebound. This is where the underlying continental plate, having been pushed down into the mantle, is relieved of the force acting on it and rises under a process known as isostasy (buoyancy) until it reaches its equilibrium. Interestingly this process happened (and is still happening) in Britain after the last ice-age. So it could be argued that if the ice were to melt then initially Greenland would be much smaller (possibly many islands) because much of it would be under water, but over time it would gradually increase in size as the bedrock rose and could possibly become one landmass. But, in the absence of accurate geological information this is speculation and so, for the moment, I would be inclined to stick with the idea that Greenland is one (the largest) island.

Any geological information on this subject would be a most welcome contribution.

costean · 140561. Wed Jan 31, 2007 5:03 am

eggshaped · 140579. Wed Jan 31, 2007 5:51 am

Does anyone else think that the map image is quite a lot different from the satellite image?

The satellite seems thinner, and with less islands. Maybe it's just the clouds playing tricks.

strukkanurv · 140582. Wed Jan 31, 2007 5:53 am

Archie · 140590. Wed Jan 31, 2007 6:02 am

Are you just looking at the snow-covered part of the satellite image?

eggshaped · 140611. Wed Jan 31, 2007 6:30 am

I don't think so. For instance, look at the south coast. As it heads North-Eastwards it is fairly smooth, the drawn map has all number of coves and inlets.

costean · 140656. Wed Jan 31, 2007 7:59 am

I think that particular satellite image is taken at a slight angle so might be a bit deceptive.

Here is another satallite image and the map for comparison.

I think they are close enough for our purposes of making a rough estimate of the area above the 71st parallel.

A globe or a good atlas would be sufficient to check this; neither of which I have unfortunately.

<edited by Jenny because the original image was making the page hard to read>

deltadry · 142265. Sun Feb 04, 2007 4:41 pm

One of the most interesting things about Greenland, and there can't be many, is that on all the most commonly used map projections it looks HUGE. But if you look at a globe Greenland is actually only about the same size as Mexico.