The ancient shields of paradise

By Phil Plait | June 19, 2012 6:30 am

[Note: At the bottom of this post is a gallery of astonishing pictures of volcanoes taken from space.]

Note to self: visit Tahiti someday.

Why? Because this:

[Click to breathtakenate, and yeah, trust me here, do it.]

This image of Tahiti was taken by Landsat 7 back in 2001. We may think of Tahiti as a tropical paradise — because it is — but like so many other islands in French Polynesia it’s actually a volcano. In fact, its two: Tahiti Nui, the bigger one to the northwest, and Tahiti-Iti to the southeast. Both are shield volcanoes, built up from lava flows. Nui is older, with hardened lava flows ranging from 300,000 to 1.7 million years old, while Iti is somewhat younger, only a mere 300,000 – 900,000 years old. Both volcanoes have had events where the shield has collapsed, so there are no classic circular holes in their middles.

Not only that, but their appearance has been heavily modified over the millennia by rainfall and erosion. Those deep crevices are where water has flowed down and eaten away at the slopes, and the color is of course from vegetation that thrives there. All of this makes the pair less volcano-looking and more oh-my-god-I-want-to-visit-there-looking.

See that little triangular jut-out of land at the very top of Tahiti-Nui? That’s called point Venus, and is where Captain Cook landed to observe the 1769 transit of Venus (you should read that link; it’s a cool story). It took them nearly a year to sail from England to Tahiti. Not too many scientific expeditions these days take that long to reach their destinations… with the notable exception, of course, of planetary probes, which can take much longer than that to reach their own Point Venus.

I’ve been to three volcanoes in my life — Taburiente on the island of La Palma, Pululahua in Ecuador, and Crater Lake in Oregon (one of the most astonishing places I have ever been). They are magnificent, transcendent places, and one day, I think, I’ll find a way to visit this pair of craggy, warm, and fantastically beautiful volcanoes so far away.

NASA Earth Observatory image by Jesse Allen and Robert Simmon, using Landsat data from the U.S. Geological Survey.


CATEGORIZED UNDER: Pretty pictures, Science

Comments (22)

Links to this Post

  1. Tahiti from Space | A Few Reasonable Words | June 24, 2012
  1. Again, if you had gone in another direction, I could see this blog being claeed Bad Geology or something, and Dr. Phil Plait would be a vulcanologist. :) Great pictures.

    You haven’t been to the Hawiian volcanos? For some reason I figured that would have been a no brinaer for you (astronomy and volcanos all in one trip). And I also have to recommend Icelandic volcanos. Visiting there where you can see two tectonic plates separating is just too cool.

  2. Marc C

    I trust you’ve read Simon Winchester’s “Krakatoa: The Day the World Exploded”? It’s an absolutely marvelous tale of geology, colonialism, geomagnetism, plate tectonics, the beginning of the global communications network, Islam, heroism, and one nasty ass explosion.

  3. Chris

    @1 Larian
    You beat me to it. Mauna Kea counts as a volcano doesn’t it? And Mauna Loa not to mention a bunch of others are just a hop, skip and a jump from there.

  4. kennypo65

    Wow! Just look at all of those reefs surrounding both islands. This is a scuba diver’s paradise. Thank you Dr. Plait, I’m going.

  5. ND

    You can see the airport at the upper left corner of the big island.

    The colors are awesome. Dark blue with strong green with a ring of turquoise. Nature is beautiful.

    I wonder if that thin section connecting the two volcano islands is in danger of being submerged if sea levels rise.

  6. Trebuchet

    I’ll just toss in a recommendation for a visit to Mt. St. Helens. It’s amazing and scary to realize how powerless we humans are on a geologic scale.

  7. toffer99

    I’ve been to the top of Vesuvius, in southern Italy. Its well worth the trip if you’re in Italy. When I got there it felt thoroughly alien, as though I’d left Earth behind. It was quite a disturbing sensation and lasted until we got back down to the line of normal vegetation.
    As you say, Trebuchet, a bit of heavy geology really puts you in your place as a human being.

  8. Mark Heil

    So I imagine these two volcanoes formed over the same hot spot similar too the Hawaiian islands? With Iti being the newer volcano, you can picture the plate moving to the northwest over the hotspot. The difference being that the Tahitian hotspot is no longer active. Or are there newer island to the southeast formed by the same hotspot?

  9. Marina Stern

    I’m surprised that you claim to have visited only three volcanoes, since you live in the West. The Cascades are all volcanic, and, I believe, so is the Sierra. Spend a week or two driving from central California, through Oregon, and into Washington; you’ll be hooked forever. Hint: if you drive up the 97 through Oregon, you can have as many as 10 volcanoes in your field of vision at the same time.

  10. Chris

    May I humbly suggest you add Mauna Kea and Kilauea to your list? As an astronomer, you might enjoy visiting the observatories on Mauna Kea, and live lava flows at Kilauea are amazing. Highly, highly recommend it.

  11. Matt B.

    @10 eyesoars – Aw, man, I must have driven right past Capulin and not recognized it as a volcano. And apparently I should visit Park County, CO, sometime too. It’s only 80 miles or so away.

  12. I second the recommendation of Kilauea. It’s pretty amazing.

  13. MadScientist

    Don’t miss out on Pu’u-o’o in Hawaii (Hawaii itself is made up of 2 monstrous volcanoes with Mauna Loa being the largest mountain on the planet when measured from its base). The vegetation in Hawaii is also somewhat unique – it’ll certainly look very exotic to anyone from the US mainland.

  14. Even better, look at an aerial image of Bora Bora. It has a more solid reef and a huge lagoon ringing one central volcanic island. It’s gorgeous!

  15. Bramblyspam

    I can’t believe Phil hasn’t been to Haleakala. Go there, watch the sunrise from the summit, then bike down. There are tours for that sort of thing, and it’s well worth doing.

  16. CR

    I’ve always understood why so many people over the centuries have found Tahiti to be a destination worth visiting, based on surface and aerial photos of the twin islands, and this image proves that even from space, it’s gorgeous.

    As for Bora Bora, I’ve seen lovely aerial pics of it, and it’s also a destination for me. (I’d best get going on actually visiting some of these places before I get too old or too poor to do so!)

  17. Nigel Depledge

    Edinburgh Castle is built on the basalt plug that is all that remains of a long-extinct volcano. Have you ever been to Edinburgh?

  18. DaveH

    Can I also recommend the day-by-day blog of Cook’s Journal,
    http://jamescookjournal.blogspot.co.uk/
    with the journal of Joseph Banks and one of Cook’s lieutenants appended. The transit was a week or so ago, but the first impressions of Australia are yet to come. Fascinating stuff. Cook’s journal is very professional and quite technical, but Banks’ is very lively and quite funny.

  19. Mick

    I live on the Gold Coast in Australia, and the mountains of the hinterland are the northern face of the massive Tweed Caldera, an ancient volcano. It has mostly eroded away, leaving a ring of mountains which can be easily seen on Google Maps. http://goo.gl/maps/IiKb

    In the center of the caldera lies Mt Warning, which is the volcanic remnant that has resisted erosion compared to the surrounding landscape, and towers over everything when viewed from the coastline.

    Captain Cook connection: Mt Warning got its name from Cook’s voyage to the east coast of Australia. The crew of the Endeavour used the location of the mountain to warn other ships of the dangers that lurk upon the coastline in the days before anyone had a chance to build lighthouses.

    The rest of the region is a smorgasbord for geologic delights. As one example, in times of bad weather, rough seas can reveal pumice rocks that have been buried under the beaches for 23 million years.

  20. Years ago, my wife and I went on our honeymoon to Bora Bora, Moorea, and Tahiti. We charged it to a credit card and took over a year to pay it off. It was worth every penny. I’d highly recommend going to Bora Bora and Tahiti at some point in your life.

    For a travel tip, we got one of the huts on the beach, not one of the ones over the water. At the hotel we were at on Bora Bora, we’re glad we did, because the beach huts had more privacy than the overwater ones, and were just as stunning being only yards away from the water.

    Oh hell, I wasn’t going to blog-whore, but instead of writing a book for a comment, I’ll just link to my site to describe our experiences there:

    French Polynesia Travelling Tips
    French Polynesia Photos

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