GeologyRocks

Hi, I think that on Wednesday I'm going to exactly the same place your describing. We're going to polish up on our mapping skills ready for the projects next Summer. Have fun while you're there.

I'm not sure of the exact area at present, but I gather its just north or north east of Madrid.

 I'd love to hear about your trip when you get back please.

 John

“Civilisation exists by geological consent, subject to change without notice.” -  Will Durant

Hey John,

Just got back form my mapping in Spain,

We stayed in La' Cabbrera, losts of Granite and Granitic Gneiss, and mapped in an area a little bit North of Torellaguna, Lots and lots of Slate, Limestone and conglomerate/Sandstone.

A very Big unconformity between basement slates and later sands, and a lot of dolomitised limestone.

The entire area is criss-crossed by faults, some little with a small displacement, and some huge that cut the whole area. the entire formation is trending North, and there are some really spectacular outcrops of spotted slates, and normal slates, a few quarries with good exposures, and a few places where it's really easy to spot slicken-fibres. 

A few fossils in the limestone, and a few shell fragments in the Sands. The area involves a hell of a lot of walking up some very steep faces, but has some very good geology. Hopefully you wont have the heat like we did because your going 2 months later.

If you want any more information just let me know (I have  a hell of a lot of of field notes) 

Leah 

Hi Leah,

 Thanks for all that info.  Is this La Cabrera north of Madrid (where I shall be going)?

I shall try and find out out actual location this week - those field notes of yours might really come in useful! 

John

“Civilisation exists by geological consent, subject to change without notice.” -  Will Durant

Hey Jhon

   The entire area is north of Madrid! If you need anything just ask I'll be happy to help!

Right.  Great news. Thank you. I'll get in touch with our beloved leader this weekend and put some pressure on him to tell me what he has planned!  Then I'll get back to you..

 John

“Civilisation exists by geological consent, subject to change without notice.” -  Will Durant

 Hi Leah,

 I have unashamedly copied and pasted the into.  So you can pick the bones out of it now.  I must admit I haven't even looked at a map yet - and probably won't have time until I'm on the ferry!

Introduction   The purpose of this trip is to study the rock types, geological structure and history of two related but distinct areas; the Sierra de Guadarrama, a horst of mainly Palaeozoic rocks deformed, metamorphosed and intruded by granites during the Variscan Orogeny, involving the collision between Gondwanaland and Laurussia to form Pangea at the end of the Carboniferous period (but also including some folded Mesozoic, especially around the edges, uplifted between the Duero and Madrid Tertiary sedimentary basins in relatively recent time (Miocene or younger). The other area lies to the north, around the city of Burgos, lying close to the corridor between the Duero and Ebro sedimentary basins.  There are Paleozoic rocks exposed in the Sierra de Demanda inlier, a horst lying to the south of the La Rioja trough; these have again be deformed by the Variscan orogeny, but less a degree than the Guadarrama. Deposits ranging in age from Stephamian (uppermost Carboniferous),  to Triassic were laid down  unconformably on top of the eroded Hercynian belt.  The subsequent history of the region is tied up with the opening of the Bay of Biscay between N Spain and Brittany, which involved an anticlockwise rotation of about 30^o . Extensional  sedimentary basins opened on the north coast, whilst to the east the SE shifting of the Iberian microplate created basins in the Pryrenean area controlled by strike slip faults.  Thick sequences of Cretaceous sediments accumulated in these basins, shallow  marine to begin with, followed at the end of the Cretaceous by unstable turbidite “flysch” , which continued into the Tertiary.  During this time the Cantabrian area became the site of southward subduction of Bay of Biscay oceanic crust, the scraped off, thrust and folded sediments forming the Cantabrian chain.  Large quantities of clastic “molasse” sediments were produced by the erosion of the rising mountains which accumulated in basins to north and especially south.  These foreland basins were partly formed by the weight of the rising mountain chain and by the moving thrust sheets, leading to deformation of the sediments during and just after deposition.  Evaporite beds in the deeply buried Triassic were mobilised and rose as salt diapirs.  The area is still undergoing erosion and huge amounts of sediment have been deposited in the Ebro and Duero Basins.  This, together with the dry climate and the youthfulness of the structures makes the area a classic one for exposure of two orogenic belts on a grand scale.

 I'd be glad to know of any areas mentioned that you went to. 

John

“Civilisation exists by geological consent, subject to change without notice.” -  Will Durant

Joh, 

firstly I have to thank you, my follow up work is to compose an illustrated Geological History of the area, so the piece you posted is quite valuable as a starting point.

From the above discription I think my mapping area was across a section of the Cantabrian chain. I didn't really get to see a whole lot of the Granite of the Gneiss, except for on the last day. It all sounds a lot like what I mapped. Hope you enjoy it there, and if you need any field note information, let me know, I'll be happy to help.

Leah 

Hi Leah,

 Many thanks for your response.  Unfortunately it looks like I won't be going.  My mother, who is quite elderly,  has had a bad fall and is in hospital. In view of that I think I have to bow out of this one and be here.   In view of that I might take you up on the offer of your notes so at least I can see what I'm missing!

I shall probably have a few days out in this country where I an contactable by phone and can get to Minehead area reasonably quickly.

Thanks anyway.

Disappointed John

“Civilisation exists by geological consent, subject to change without notice.” -  Will Durant

I'm very sorry to hear that John. I hope all is well soon, and of course you're welcome to the notes, but I have just handed my note-book in for assessment, so when I get it back I shall scan the pages in and email them to you.

Again sorry to hear about your Mother,

Leah