Mantle in the Mountains - Day 4

Jan and I now know Ronda's shopping streets pretty well - we were looking for a gift for our leader, Tom, and thought that a "proper" Spanish pocket knife would fit the bill so we set out up one street and down the next looking for the right sort of shop. The chap in the one ferreteria we found didn't have anything very exciting but directed us to a "proper" knife shop.... which unfortunately was closed for the day. That exhausted the main town so we headed over the Puente Nuevo into the old town, getting a great view of a parade in passing - bandits, mules etc. It was like stepping back into the pages of Washington Irving's Tales of the Alhambra!

Luckily we found a really good quality, hand-made knife quite quickly so, that done, enjoyed the rest of the morning - though it was a shame we missed the walk down the gorge... must do that next time!

After lunch we set out to the west of Ronda, turning off towards Montejaque and stopping first for an overview of the geology around the embalse.

Montejaque embalse - dry when we were there

The grey rocks are Jurassic limestone on the edge of the Sierra de Grazalema and have been folded until nearly vertical. We are on the edge of the Ronda Basin which underwent late stage extension in the Late Miocene (Tortonian/Messinian) and is partly filled with a lot of Neogene fan and distal basin fill deposits. The Taco fan delta is at the edge of the Ronda Basin.
The scenery here is upland pasture on the flysch between the knolls of limestone. The flysch is marine, but includes frosted Neo-Numidian sand grains from the Sahara area. On the whole the flysch is muddy and poorly exposed, but does have occasional sandstone beds and some olistostrome. Unclear if it is unconformable or whether there is a structural contact.
We drove on down the gorge below the dam, turning right up a track before the village of Montejaque where we found marly limestone as seen the previous day, and had an opportunity to examine the limestone in a small quarry.

The gorge below the dam

The limestone/olistostrome and flysch scenery

Exposure of marly limestone

Limestone outcrops near the hilltop but the grassy slope below that is where there is a flysch covering

View east towards Ronda, sitting on its crags of fan deposits at the edge of the Ronda Basin

Mantle in the Mountains Day 3 - South-west of Ronda

The route for today went through Benaojan, Jimera de Libar, Benalauria, Algatocin, Jubrique and Atajate, to look at Low grade Alpujarride cover of peridotite in the Internal Subbetic.
The first Locality was the Cueva de la Pileta south of Benaojan where there are prehistoric cave paintings.

The parking area is below the cave which is 35 m higher up the hillside, reached by steep steps

Information board about the cave system

I have a thing about spotted horses!

A fish

From the Cueva de la Pileta we continued south-east over the steeply dipping Dorsale Limestone ridge, and turned off the road to look at an exposure above Benalauria. This is the Malaguide unit which here comprises Palaeozoic schist and phyllite of Silurian to Carboniferous age. In other areas there are younger rocks in the Malaguides - up to Cretaceous - but not here.

Locality 2, the Benalauria road cutting

At the downhill (eastern end we say two lithologies: a hard, twinkly, dark grey rock and grey, smooth, shiny phyllite. Moving uphill there were thinly laminated rocks with upright folds.

Upright folds

In a brecciated zone we saw iron and calcium carbonate.

Yellow staining by iron and calcium carbonate

There were examples of plastic and brittle deformation
Near the top some carbonaceous material (sulphur? pyrite?)

Brittle deformation - low angle faulting in vertical sediments

Returning to the main road we turned downhill past Algatocin to look at exposures on the road section to Jubrique and Genalguacil.

The Jubrique road section

Graphitic mica schist, with quartz and feldspar blobs showing signs of deformation. We also found pink andalusite, gold coloured, translucent biotite and garnet. The metamorphic zones here have been condensed by pressure top left to bottom right.

After a lunch break we headed back up the hill to Atajate mirador which is a great viewpoint for Peridotite, Malaguide and Dorsale Limestone units.

Final stop of the day was a short drive north of here where a road cutting exposed red and white striped Cretaceous marls.

Cretaceous marls exposed in a road cutting 

The white limestone beds don't warp although stylolites are evidence of pressure

Beds of red marl take the strain as in this example of shear

The Cretaceous marl is downfaulted against the older, Dorsale Limestone; the junction is visible near the next mirador travelling north.

Tomorrow, a morning off in Ronda (with a chance for people to walk down into the Tajo, and out to nearby Montejaque in the afternoon