Thursday, 19 October 2017

Lessons From A Canary Island - Rock of Ages

The core of an old volcano, Gran Canaria
The great thing about going to somewhere different is that you see different things - if you look.

We've just got back from a little over a week in the Spanish Canary Island, Gran Canaria, just off the coast of West Africa. Yes, it's where the Canary finch comes from but, apart from a brief glimpse that might have been one and a couple in a cage, we never saw any. In fact, we saw very few birds. A few buzzards, a couple of kestrels, some egrets and herons and quite a lot of gulls, but nothing to get excited about and no new species to cross off my list!

This is mostly because Gran Ganaria is hot and arid and, being volcanic, has very little soil for anything much other than cacti and other succulents to grow in. There are pine woods on the higher places but still not a lot of wild life.

And this means that a great deal of the underlying geology is, well, not really underlying so much as overlying and exposed. It's black volcanic tuffa, pumice, basalt and towering columns of extinct volcanic core with the core eroded to expose the solidified magma as in the photograph on the right.

This, of course, if only they would look at it, is a problem for creationists because there is no way to explain the geology of Gran Canaria in terms of the product of a recent global flood or of volcanic activity in just a few thousand years since one. It is, quite simply, as close as science comes to proof that there never was a recent global flood and the Earth is actually very old. Although, on the accepted scientific understanding of the age of Earth, the Canary Islands are comparatively young - i.e., just a few tens of millions of years old.

The photograph on the left (taken through the window of a moving coach on our way to the airport) is of a cutting to make the one major road on the Island, GC1, along which we always seemed to be driving to or from somewhere. We do beaches and swimming, but not all day every day. We explore and go there just to say we've been there and to see what we can see!

But anyway, this photograph shows the formation in a local outcrop along the southeast of the island. Take a close look.

First, a disclaimer. I'm not a geologist so I'm talking as a lay-person here. Please forgive me if I us non-standard terminology or ten words where one technical one would have done.

Immediately behind the steel crash-barrier is a man-made wall. Ignore that. Just above it is a brownish layer consisting of small horizontal strata but from the centre of the picture towards the right, this takes a dip into what looks like a cross-section of a shallow dip. This has clearly been cut through the strata which are not distorted. Above this layer and filling the dip is a pale layer with similar horizontal strata. This layer fills the dip and builds up in layers, spreading out on either side, just as you would expect a sedimentary deposit to build up as water filled up a lake or a river bed or whatever caused that dip to be cut through the lower layer.

From where we were, not being able to stop on the motorway and go take a look, this looks like sand (maybe wind-blown, maybe a beach) on top of which limestone or chalk was deposited later when covered gradually by a rising sea.

Then we have a sudden sharp change to volcanic basalt. The central volcano has blown up and poured magma over the lower two layers. Look at the left hand edge of this picture and note how, even though the overlying strata have eroded away, this hard basalt has barely had its surface scratched.

The photograph on the right is the same formation a few yards further on, taken as the coach sped on. It basically show the other side of that dome of rock sitting on top of the basalt. Note that the finer strata in this thick layer are also in the same plane as the lower strata. They appear to be volcanic ash, deposited over time after the initial magma flow and then weathered and cut into hills and valleys (I'm open to other interpretations here, as elsewhere).

Now to the point!

Had this predated a global flood a few thousand years ago, we should see a single sedimentary layer overlaying the whole column (and, incidentally, providing the island with a nice, rich alluvial silt in which the inhabitants could now be growing superb crops instead of struggling to scratch a living and depending almost entirely on tourism for their income.

Had it postdated a global flood just a few thousand years ago, all of these strata would have to have been laid down, eroded, covered in water, exposed again, covered in magma and then covered in volcanic ash which solidified and eroded into the hills and valley we see today, in a matter of a few thousand years and certainly well before the islands were first inhabited in prehistoric times. It's not known exactly when they were first inhabited, almost certainly by Berber people from northwest Africa in pre-classical times, i.e. 2-3,000 years ago.

Is that at all feasible?

Or is the following a better explanation?

Gran Canaria Geology
The Canary Islands are a volcanic archipelago which lies off the coast of north-western Africa.
Although there is some debate over the cause of the Volcanic Activity in this area, the most probable theory is that the Islands were formed by the dual processes of a Hot Spot (or Mantle Plume) and the proximity to the Geologically Active Atlas Mountains.

The Hot Spot theory suggests that, as the diverging African and South American tectonic plates separate, the Canary Islands were formed as they crossed a mantle plume that sent molten rock to the surface. The fact that the Canary Islands get older as they go from West to East (Lanzarote and Fuerteventura are the oldest) supports this theory.

The origins of the dramatic scenery of Gran Canaria began about 15 million years ago with the first submarine building stages of the Gran Canaria Volcano. The first sub-aerial activity took place about 14 Million Years ago. This shield-building phase (growth phase) continued until about 9 Million Years ago when there was a massive collapse that formed the 20km in diameter Tejeda Caldera. While this Caldera isn't as clearly defined today, parts of it's enormous walls can still be seen.

After the collapse, the Caldera gradually filled up with Lava and other volcanic material over the next few million years. This period was followed by 3 million years of volcanic inactivity and erosion.

The next major stage, between 4.5 and 3.5 Million years ago, was characterised by explosive eruptions. This was again followed by a period of erosion.

Gran Canaria is now in it's Post-Erosional stage with it's last eruption taking place at Bandama about 2000 years ago.

But of course it's not just in Gran Canaria that you can see the evidence that the Biblcal flood myth is just that - a myth. You can see it in every geologically active part of the world (creationists really should try to get out more; not everywhere is like Kansas or Texas). You can see it where we were a couple of years ago around Naples in Italy. You can see it in Snowdonia, Wales where you can also see the effects of glaciation adding a whole new dimension to the geology.

There must be places in the USA where a creationist can go and see the irrefutable evidence that Earth is very old, if only they weren't afraid to look. Maybe they do. Maybe they're just too afraid to admit it.

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