The Cordoba Mezquita Geology Museum

[Peregrinopaul]

I’m indulging myself here, as an ex geologist. When I visited the Mezquita in 2018, I was astonished at the beauty and variety of source rocks for the celebrated 850 columns of the hypostyle hall. I shouldn’t have been, because apparently they were recycled columns from previous Roman and Visigoth sites from all over Spain. Columns are particularly effective at displaying petrology on a grand scale, because of course they are polished fresh rock. One example particularly engaged my attention.

This is a classic example of an olistostrome breccia. These rocks outcrop extensively on the southern side of the Guadalquivir valley. They represent what are called mass transport deposits, giant slump features on a scale of cubic kilometres, formed during the severe deformation of sedimentary layers when continental plates collide - in this case the African and European plates about 15 million years ago. On this map you can see the occurrence of slump deposits on the northern front of the Betic Cordillera, extending from east of Jaen as far as Cadiz.

There is a postscript to this. In 2019 I stayed at an airbnb in the centre of Avignon, a converted apartment in a 17th century house close to the Palais des Papes. In the lounge was this fireplace. the owner called it marble. I disagreed.

 

[Peregrinopaul]

The owner of the Bnb turned out be a research scientist at the university. I gave him the long version. He said it would make a great after-dinner story in the future... "this crazy Australian and his enthusiasm for the fireplace".

 

[C clearly]

In the lounge was this fireplace. the owner called it marble. I disagreed.

And what did you call it?

It is interesting that I wouldn't choose to have that particular stone as a decorative feature in my house, but when its origin is explained, we can develop a much different appreciation of the appearance.

 

[Deleted member 73526]

the owner called it marble. I disagreed.

I don't anticipate being able to retrieve "olistostrome breccia" from my memory when the need arises. For those of us who are merely disagreeable, without being disagreeable recovering geologists, is there a vernacular term for our hosts' mock-marble furnishings? Could it be .... "mudstone"?

 

[VNwalking]

Could it be .... "mudstone"?

Uh-uh.
A different beast altogether. I'll let Paul chime in with a possibility.

 

[C clearly]

Uh-uh.
A different beast altogether. I'll let Paul chime in with a possibility.

I knew you would be interested in this thread, VN!

I don't anticipate being able to retrieve "olistostrome breccia" from my memory when the need arises.

Once retrieving it from memory, pronouncing it fluidly in conversation would be a more serious problem.

 

[VNwalking]

pronouncing it fluidly in conversation

Thus labelling one as a geogeek.
Chaoic and jumbled up underwater deposits getting cemented together into rock do call out for an evocative common name.
I vote for 'apocalyptic breccia.'
When those slumps happened, it sure would have been the end of the world for anyone in the vicinity.

 

[Peregrinopaul]

And what did you call it?

.. is there a vernacular term for our hosts' mock-marble furnishings? Could it be .... "mudstone"?

I hope I did not come across as being irritatingly picky but I was intrigued and quite thrilled to see such a distinctive rock-type used in this way - in both locations. I agree and have no intrinsic objection that colloquially we all refer to most polished stone whatever its origin as marble, except in distinguishing crystalline rock as polished granite, which similarly it may not be.

In any dictionary marble is defined as metamorphosed limestone, (or or a glass sphere beloved of most males of my generation in their youth!) But who cares?

But in this case the breccia contributes to an amazing story of continents colliding and a vanished ocean, Tethys.

 

[VNwalking]

But who cares

Picky geogeeks?
I don't care either...and am always awed when faced with evidence that the seemingly solid crust of our earth is like the scum on a simmering pot of soup.
Plus that rock just looks spectacular.

 

[C clearly]

I hope I did not come across as being irritatingly picky but I was intrigued and quite thrilled to see such a distinctive rock-type used in this way

Actually, we (well, at least 3 of us) were quite intrigued, too!

 

[VNwalking]

And this led me to an app that I wasn't aware of, an interactive ICS Timescale. It's very cool, because you can access all kinds of specific information about sites defining boundaries between geological strata. Click on the wheel and you get a map with specific type locality. For example on the Camino Viejo:

 

[Peregrinopaul]

I'm digging a hole for myself, but I got a buzz out of these too!
...granite fence posts?????

You can wait with bated breath for my next instalment, "On this Day in May". May 22nd 2018, Almaden ...(the other one).

 

[Peregrinopaul]

And this led me to an app ...

I'll respond when I've checked this out ... I have time on my hands

 

[VNwalking]

granite fence posts

I'd have missed that, assuming concrete....

 

[Deleted member 73526]

I hope I did not come across as being irritatingly picky

Not at all. I thought you were very entertaining - both to us and to your host. And I admire the scholarship and expertise that people share here - the geekier the better.

It's sometimes hard to get a humorous sentiment across over the interwebs. I picked up the word "disagree" and turned it into "disagreeable" (which I also levelled at myself). And recovering geologist for ex-geologist ... Well, I was aiming to convey a gentle ribbing.

 

[Deleted member 73526]

granite fence posts?????

Hooray. I am no geologist also thought that those were extraordinary. I think I mentioned in my diary that they seemed so extravagant, but must have been an economical / readily available material.

 

[Peregrinopaul]

And this led me to an app that I wasn't aware of, an interactive ICS Timescale. It's very cool, because you can access all kinds of specific information about sites defining boundaries between geological strata. Click on the wheel and you get a map with specific type locality. For example on the Camino Viejo:
View attachment 100613 View attachment 100614

Having navigation trouble. How did you come up with the wheel for the Santonian in your first pic?

 

[VNwalking]

How did you come up with the wheel for the Santonian in your first pic?

That wheel is what came up for me when I opened the app.
If you spin it, you can see the pins on the edge of the wheel; [EDIT:] click on "see more" in red at the bottom left of the screen to access the map.

 

[Peregrinopaul]

Hooray. I am no geologist also thought that those were extraordinary. I think I mentioned in my diary that they seemed so extravagant, but must have been an economical / readily available material.

It beats me how cutting, or at least cleaving the toughest rock on the planet into fence posts would occur to anybody!

 

[Peregrinopaul]

That wheel is what comes up when you open the app.
If you spin it, you can see the pins on the edge of the wheel; click on one of them to access the map.

Maybe there's some Apple incompatibility. The wheel is completely passive on my Mac.
And curiously it suggests searching "ICS timescale" on the appstore, and I came up with nothing (on my iphone).

 

[VNwalking]

It beats me how cutting, or at least cleaving the toughest rock on the planet into fence posts would occur to anybody!

Well, you'd only have to do it once.

The wheel is completely passive on my Mac.

Bummer. I'm using an Android and it works perfectly. Does it move at all. with a MYBP# changing in the middle of the screen on the left margin? If so, hover over anywhere there's a yellow pin and see if there is a link that appears on the lower left. (Sorry. I edited that post above to make that clear).

 

[Peregrinopaul]

I am no geologist...

Well, neither am I really, not having worked in the field since 1974. (Life takes some quirky turns). Nevertheless it has been a lifelong interest and a fair proportion of the books on my shelves are specifically geological, not to mention a fair proportion of photos on my phone.
And maybe I should recommend a fascinating book to you guys. it's approach is quite unique, and the content completely up-to-date.
.

 

[Peregrinopaul]

Hey, it's nice to be in your company. I'm so used to peoples eyes glazing over when I wax lyrical about rocks.
Here's my brother when he accompanied me to the NW Highlands of Scotland.

 

[VNwalking]

DItto.
And...

I see those rocks behind him, too...

 

[Peregrinopaul]

To be fair to my brother, we staged that photo for a laugh. “ Rocks? What rocks?” That road cutting is heritage-listed.

 

[Peregrinopaul]

With respect to my first post, I was astonished this morning to see on the news images of the interior of the Jackson Mississippi legislature.

 

[VNwalking]

Ummm.
Where did that olistostrome breccia come from, I wonder?

Skimming wikipedia about the geology of Mississippi, it seems unlikely to be from inside the state. So I went looking and this is all I found:

More than 10 types of marble from other states and countries are found throughout the Capitol.

So if it's from the US, the USGS says either Rhode Island or Washington State. Could be Spain too.

(That's quite a look. A bit too much action for my taste.)