Thursday, August 29, 2013

San Cristobal Interpretation Center, Natural and Social History

We'll start our tour of San Cristobal, the Galapagos island closest to the continente, at the Interpretation Center, but make a few diversions and finish with a bibliography, just like at school. 

This facility, a gift from Spain,  is about half a dozen years old and is devoted mainly to natural history and the human history of the islands. 

It's pretty well done and worth the visit. I "read" it cover to cover. 

Apparently there was more going on in the Galapagos in the last 500 years than in the last 5? million, and plenty just in this century.
Geologically the Galapagos islands are unusual, being volcanic in origin, currently active, and located at  the junction of three different tectonic plates riding over one another. The islands have arisen in the west and are sinking below the sea in the east. 
The newest island is Fernandina, a fresh shield volcano of 500,000 years, whose lava continues to leak from a hot spot beneath part of the Nazca plate into a bay close to western Isabela, the most western island. 
The oldest islands are the eastern ones, Espanola and San Cristobal,  and they are expected to eventually subside below the sea.

At the same time, ocean currents swirl around, five of them in an intricate dance to the rhythm of the prevailing trade winds - no wonder water temps and sea conditions are so variable in the Galapagos. The nutrient-rich Humboldt Current originates in Antarctic waters so it's cold enough to cool the air, leading to the odd sensation of sleeping under blankets near the Equator. A fine mist, the garua, forms at higher altitudes, but the arid zones are less affected.  I'm told that from January into April, when northeasterly trade winds prevail, the Humboldt loses its grip so the weather is hot and it rains many afternoons, unlike the temperate conditions we experienced during July. Then there are the El Niño years when 'normal' is turned upside down.

The Galapagos are of course noted for the large number of endemic species, known nowhere else in the world, that developed in its isolated location.  

The famous ones are the tortoises and iguanas, which probably drifted in on logs from South American rivers but survived because there was no competition from mammals (tortoises) or adapted (the marine iguanas learned to swim and dive to the bottom). 

Several birds are special: the penguins, the flightless cormorant. Others, like the albatross, simply thrive in the isolation. The finches developed differently on each island from a common ancestor; Charles Darwin was  able to adapt or diversify his observations of them into a successful new theory.

The most notable mammal is the Galapagos sea lion. I like to think of this image as having persisted for umpty-thousands of years. 

Behind my back, though, are youths with surfboards, sunbathers, tourists with cameras, all new in the last century. I wonder what the sea lions make of it.