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GEOLOGICAL MUSINGS 2
BARONAL

Baronal is a ridge separating the campilla of Genoveses from the sea on its southern flank. Where in the Western massif solid granite predominates the Baronal has a different structure. Were its material to have been ejected through terrestrial vulcanism it would probably be pyroclasts and spread over a wider area. In submarine conditions these emissions appear to have been constrained into domes producing an exotic undulating coast with corniced sea cliffs. Perhaps this is a wall formed as the caldera slowly collapsed? It spreads from Genoveses as far as Monsul where quite different tuffs appear.

Right: the start of Baronal seen from Genoveses head. Right below: the main stretch of Baronal with the western massif in the distance. Left: complex layering of successive volcanic emissions can be seen on this rocky bulkhead. Semi molten material is visible at the base, a thick layer of tuffs, then pyroclast conglomerates (What does one call these when in a submarine environment?) capped by a columnar basalt flow. Are the cornices caused by a heat hardened surface layer? Perhaps many millions of years are represented on this image.

Far left: granite lumps and fused hot ash cooled rapidly in submarine conditions; left: columnar basalt and a basalt pinnacle; right: columnar basalt and the very fine sand erosion by sea and wind creates from these materials.

All these rocks resist erosion & the Med has less force than ocean. Above & left show how  tuffs go first. Right: complex pattern of basalt flows on a cliff face at the western end  of the long Baronal beach. Discontinuities in the range are also interesting perhaps seismic in origin during lift & collision?

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CALA DE LAS AMATISTAS

The structure of Cala de las Amatistas (amethysts) is interesting. On either side tall andesitic cliffs rise sheer over 20 metres The cove itself, like most others on this coast, is the seaward end of an eroded ravine where more friable matter has been carried away. Squeezed between these cliffs is what appears to be the remains of a hydrothermal vent around a lava extrusion and it is from this that amethyst & citrine fragments emerge in the rubble. Hunting them is a relaxing way of spending an hour (or two) in tranquility filled only with the sound of sea around the crashed erosions from the andesitic conglmerates.

Bentonite is still actively quarried near Agua Amarga. It is a large quarry on the landward side of one of the coastal vulcanisms. The illustration on the left shows it stacked; that on the right shows it spread to weather. The large reef and volcano complex of Mesa Roldan (Orlando’s table - for obvious reasons, it is large and flat) is in the background. For other images of this see Carboneras. In the UK the many industrial uses to which this volcanic ooze is put are fulfilled by kaolin, which is rotted or degraded granite.

Both this page and the previous one are in the process of revision of the text. Much of the time I am feeling my way here and discovering better interpretations.

UNDERSEA

VULCANISM