Geology in the raw in the Galapagos

This entry is being typed en route to Fiji from L.A.  Mom just joined us in L.A.  With the help of a couple of good sleeping pills, I got a little sleep during the 3 flights yesterday; the kids did not fare so well.  I’m taking advantage of some down time with a little table in front of me to write the final Galapagos blog entry.  My 2nd round of sleeping pills will kick in shortly …
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3 days later … We’ve been in Fiji for 3 days now – we’re staying with friends Rhonda, Henry & Ben on one of the outer islands (Henry is from here).  Absolutely beautiful. Fantastic snorkeling yesterday.  Great fishing today.  Tenting seaside has been idyllic. Very hot but so far we’ve had cooling breezes.  Internet connectivity a challenge here hence the dearth of communication … but we’ll be busy writing in the days to come …
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The Galapagos are remarkable for many reasons.  Jake talked about the amazing “underworld”.  Kaia talked about the wonderful marine iguanas and sea lions.  I wrote earlier about the boobies and other lovely birds.  And Yvonne talked about the story of species decimation and subsequent recovery efforts.  Perhaps what is most obviously remarkable about the Galapagos is the geologic story they tell.  They are a living lab of volcanism, that is so easily explored on a cruise such as ours.

To understand these islands, you have to understand the concept of plate tectonics over a “hot spot”.  A hot spot is a place in the earth’s mantle that has magma welling up to the crust (through convection).  Scientists don’t really understand what creates these hot spots deep in the earth’s core, but the upwelling lava ultimately breaks through the crust and creates volcanoes.  Add to this the reality of plate tectonics – whereby the crust is moving over the magma below – and you get a string of volcanoes as the plate moves over the hotspot.  The most famous of such a string is the archipelago of the Hawaiian Islands.  The island over the hot spot is usually the largest and is “active” (eg. the newest island Hawaii is furthest west) while the oldest island has moved past the hot spot and is now inactive and heavily eroded.

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This is exactly what is going on in the Galapagos.  The plate that the islands are sitting on is moving east, just as the Hawaiian islands are.  So not suprisingly, the eastern islands of San Cristobal and Floreanna are nearly flat and highly eroded, while the western islands of Isabela and Fernandina have high, active volcanoes.  In fact they recently discovered (underwater) “sea mounts” off the east side of the islands (see map below).  These mounts were Galapagos Islands 4 million years ago before they were eroded away.  They also filled in a missing piece of the evolution story for scientists.  The oldest present day island is about 5 million years.  But evolutionary scientists felt like 5 million years was not enough to explain the adaptive changes of present day wildlife species.  But adding in the 4 million years of these previous islands (now sea mounts) apparently completes the evolutionary story.

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I’ll start the photo story on the island of Santiago which lies in the middle of the grouping.  We went ashore on lava that looked like it had cooled just days or years ago.  In fact it was just a little more than 100 years old.

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Santiago Island - an old volcano in the distance with a very new lava flow in the foreground

It was remarkable to walk on this lava – the patterns were fantastic.  You very easily could imagine that a liquid had cooled.

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different colours represent different mineral content - usually presence/absence of iron

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Victor is explaining all things lava. Each time we went ashore he'd remind us to wear good shoes because of the sharp lava. When we pointed out that he was taking his own advice (have a look in picture) he said his shoes were "made in Ecuador" and were up to the task. 🙂
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look carefully ... you can see where lava has cooled around a small log ... and the log has subsequently decomposed
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here's the same "log" formation ... from ground level
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classic "pahoi pahoi" lava - it looks like rope, or the skin of a cooked pudding as it is pulled back
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Victor got caught in this lava flow, but was wearing a heat protective suit so is still smiling. We had to wait till the lava cooled before we could extract him. 😉
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not your average hike!
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The extent of the most recent eruption is so clear here
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lava cactus has taken root ...and is the only living vegetation in sight
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looking back across the lava to Bartholome Island and our Floreana boat

That afternoon we climbed to the top of Bartholome Island. 

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The boardwalk up to the peak of Bartholome was built to prevent erosion caused by foot traffic. Lava cactus in the foreground.
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This plant "Taquilla" is very susceptible to erosion; hence the boardwalk

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Bartholome too was an old volcano.  But in this case, you could clearly see the small “parasitic” cones where small fissures allowed magma to form cones around the main cone.

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note the many "parasitic" cones
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a parastic cone visible from atop Bartholome, with the extensive lava flow across the channel on Santiago (where we'd just hiked earlier that day)
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later afternoon light on the Floreana from atop Bartholome
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From atop Bartholome, we could see our next day's objective - the aptly named "China Hat"

ok … just woke up.  3 more hours to Fiji ..

China Hat was a volcanic “plug” surrounded with slopes of lava.  The main attraction here was a sea lion nursery (that Kaia showed photos of).  However I was enthralled with the power of the surf crashing onto the lava shores.

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Although the islands are generally "stark" in their appearance, we would discover pockets of vivid colour like this.,

Here’s a photo I included in an earlier blog post, showing the tunnels left behind when a volcano subsided and the lava retreated from its lava tube.

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Genovesa Island is a circle - the remains of an eroding volcanic cone. The bay you see here is the crater "lake" (but is open to the sea in one spot)

In the last few days we moved west to the newest (and most active) islands of Isabela and Fernandina.  Isabela has no less than 6 volcanoes on it (its “plate” was moving a little north-south as it also moved east, hence the pattern of volcanoes (see map at start of this entry).  These volcanoes are at about 1400m, and have massive craters in them.  Even though they haven’t spewed lava in the past 30 years, they are still active; a large crater lake disappeared from volcanic activity about 20 years ago.  We went ashore on Isabella and climbed up past a crater lake just inside the island that was part salt and part fresh.

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Note our Floreana boat in the background. It carries max. 16 passengers. Next to us at this point pulled in a cruise ship carrying 100 passengers. They came ashore in waves. Glad we were on the Floreana!
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here is our mildly sunburned family, with Isabela island backdrop
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I liked the pattern formed by these seasonally dormant trees on the side of the crater. The green will come roaring back to life in the rainy season of Dec-Feb.
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looking across at 1400m Darwin volcano from Fernandina Island

Fernandina is the youngest island, and fully erupted in 2010.  Victor was leading a tour at Genovesa Island at the time and received permission to change his itinerary to take his clients to see the eruption.  Now THAT would have been pretty cool!

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Young Fernandina Island. The southern end of the island is directly over the hot spot. Note the parasitic cones (lava traveling through smaller secondary fissures)
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the shore visit to Fernandina Island at Punta Espinola was outstanding for many reasons, including seeing this reassembled whale skeleton that had washed onto the shore

One of our favorite shore visits was on the smaller island if Rabida, known as the “red island”.  I believe it is mostly a high iron content that led to this colouration.

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From this vantage point on Rabida Island we watched sea turtles swimming and huge manta rays surfacing and splashing their "wings"

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Family photo. We tried to adopt these two friendly sea lions but the Park rules have some crazy reason that forbids this.
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sorry .... couldn't resist ...
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interesting formations on Santa Cruz
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Galapagos fur seals were relaxing in the pool created by this natural bridge
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again ... we had to be careful not to step on the marine iguanas

I’ll finish out the blog with some photos that capture a bit of what it’s like to live aboard a Galapagos cruise boat.

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our crew - captain, mate, sailor, steward, engineer. Victor is not in this picture.
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sunrise on our final day at sea
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sunset over Isabela Island
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we would typically get in from our 2nd snorkeling outing by 5PM and would have chance for a relaxed drink before 7PM dinner.

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getting to/from zodiacs is something we did about 8 times/day
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the Floreana
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carrying around a giant tortoise shell is harder than it looks!

We parted company with our crew and cruise companions upon arriving back at Baltra Island.  The cruise had surpassed any of our expectations.  Unfortunately expensive – few folks (well … OK … 60,000/yr) are as fortunate as us to be able to experience this.  But probably just as well for those lovely creatures.

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All good things must come to an end ... 😦
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This logo on the plane pretty much sums up our experience in Ecuador. I now am the proud owner of a similar t-shirt to remind me.

Wow … the Galapagos.  Next entry we’ll be back on mainland.  Until then ….

Cam

  

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One thought on “Geology in the raw in the Galapagos”

  1. Great commentary and photos of the geology of the Galapagos, Cam.
    Your blog provides the reader with a good understanding of the prehistory and history of the volcanics of the islands.
    David

    Like

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