Palm trees 'grew on Antarctica'

[dipsydoodle]

Scientists drilling deep into the edge of modern Antarctica have pulled up proof that palm trees once grew there.

Analyses of pollen and spores and the remains of tiny creatures have given a climatic picture of the early Eocene period, about 53 million years ago.

The study in Nature suggests Antarctic winter temperatures exceeded 10C, while summers may have reached 25C.

Better knowledge of past "greenhouse" conditions will enhance guesses about the effects of increasing CO2 today.

http://www.bbc.co.uk/news/science-environment-19077439

[Duppers]

1. Continental Drift

Alfred Wegener brought together several lines of evidence to support his theory of continental drift. One is quite simple -- that the continents look like they could "fit" together, much like puzzle pieces that have drifted apart. Then, he noticed that when you put the continental puzzle pieces back together, other things started to fit. For example, the rock layers that form the Appalachian mountains of the eastern U.S. matched quite well with those in Scotland. Fossils found on the east coast of Brazil match quite nicely with fossils found in western South Africa. Also, he noticed that a lot of the fossilized life found in the rock record didn't fit in the climates they were found in. For example, rocks in Alaska contain fossil palm tree leaves, though there have not been palm trees at that latitude for a very long time! Thus, he concluded that the continents must 'drift' around the Earth, occasionally colliding with one another. Though his ideas were not popular at the time, they were the foundation of one of the greatest scientific revolutions in history!

http://scienceline.ucsb.edu/getkey.php?key=2842

[Viva_La_Revolution]

2. Now we call it Plate Tectonics

the plates don't drift so much as push and shove and split and crash into each other all powered by the convection currents in the mantle.
Other than the mechanism behind it, Wegener was right.

[Duppers]

4. indeedy, it is.

I was having one of my senior moments when I googled that.

[dipsydoodle]

3. As far as I'm aware

Rock formations in Scotland, north of the Great Glen rift valley, match same found in Novia Scotia. Not sure where they got the Appalachians from.

[Viva_La_Revolution]

6. yep. we used to be attached to northern Africa

even Newfoundland at the edge of the Canadian shield has bits of Africa and Europe.

The Appalachians are the remnants of a huge mountain that existed on the continent of Rodinia. it broke up about 750 million years ago when the Iapetus Ocean started forming. the next cycle brought us Pangea

[FiveGoodMen]

5. Looks like Antarctica hasn't moved much in the last 50 million years...

http://www.ucmp.berkeley.edu/geology/anim1.html

[Viva_La_Revolution]

7. 38 mil years ago glaciers started to form

the greenhouse phase kept it warmer than it should have been at that location.

[FiveGoodMen]

8. Yup.

Post #1 made it sound as if the movement of the continents might explain how Antarctica was warmer 53 million years ago.

I was just pointing out that since Antarctica hasn't really moved in all that time, we must look to changing climate to explain the palm trees.

[Johonny]

11. depends how you look at it

The antarctic Circumpolar Current started ~ 35 million years ago when the Tasmanian Seaway separates East Antarctica and Australia, and is reported to have opened to water circulation 33.5 Ma. The isolation of Antarctica by the current is credited by many researchers with causing the glaciation of Antarctica and global cooling in the Eocene epoch. Oceanic models have shown that the opening of these two passages limited polar heat convergence and caused a cooling of sea surface temperatures by several degrees; other models have shown that CO2 levels also played a significant role in the glaciation of Antarctica

So motion of the continents played a role, but likely not only reason for current climate of Antarctica.

[FiveGoodMen]

12. Okay, if you mean it that way.

Last edited Fri Aug 3, 2012, 12:53 PM - Edit history (1)

However there are other instances (longer ago or other continents) in which significant changes in latitude (of the land in question) also played a role.

Given the time frame, I don't think this was one of those.

[caseymoz]

10. Plates haven't drifted much since then.

Antarctica was warmer due likely to a greenhouse effect.

[kooljerk666]

13. It was also a dinosaur habitat..........

I can't find my DVD but 1 chapter was on dinosaurs & killer croc like amphibians, in anarctica.

It was a lush forest w/ 6 months of daylight & 6 monthes of snowy night.

I am not sure if this was recent 65,000,000 ya or way further back.

Bottom line, it was warm enough for a very diverse flora & fauna.

[kooljerk666]

14. More on Palm trees & ancient climates....

Scientists drilling into the seabed off the coast of Antarctica have made a very interesting discovery that was announced this week. The sediment cores obtained during the drilling reveal that 52 million years ago a rainforest grew in Antarctica. 52 million years is most definitely a long time, but changing from a tropical rain forest to a constantly frozen land is a huge change in temperature.

The scientists are using the discovery as a warning of global warming saying that Antarctica could be ice-free again within decades. The sediment cores the team of researchers recovered revealed fossilized pollens. According to the scientists, those pollens came from a near-tropical forest that covered the entire continent of Antarctica during the Eocene period between 34 and 56 million years ago.

http://www.slashgear.com/ancient-rain-forest-discovered-in-sediment-cores-from-antarctic-seabed-02241444/


Bye bye NYC, cya later Jersey........ I am buying land in New England, at least 1500 ft ASL, and far, far away from the coast.

[jakeXT]

15. Precession effects or imprecise continental drift backdating ?

The Milankovich Theory

The big questions are, of course, what caused those glaciers to spread, and will it happen again? Actually, no one is yet completely sure. But an intriguing idea, due to work in the 1930s by the Serbian astronomer Milutin Milankovich, may link them to the precession which Hipparchus discovered.

As already noted, the Earth's orbit is not perfectly round, but is slightly elongated. The Earth therefore comes closest to the Sun in the first week of January (the exact day varies a little). It means that just when the northern hemisphere experiences winter and receives the least amount of sunlight, the Earth as a whole receives the most (the swing is about 3%, peak to peak). This makes northern winters milder, and northern summers are milder too, since they occur when the Earth is most distant from the Sun.

The opposite is true south of the equator: the beginning of January occurs there in summer, and therefore one expects southern summers to be hotter, and southern winters colder, than those north of the equator. This effect is however greatly weakened, because by far most of the the southern hemisphere is covered by ocean, and the water tempers and moderates the climate.
[IMAGE recession of Earth Axis]

Right now, northern winter occurs in the part of the Earth's orbit where the north end of the axis points away from the Sun. However, since the axis moves around a cone, 13,000 years from now, in this part of the orbit, it will point towards the Sun, putting it in mid-summer just when the Earth is closest to the Sun.

http://www-spof.gsfc.nasa.gov/stargaze/Sprecess.htm