Basins and ranges

The Sorbas basin transect always makes a good first day on this trip because of the stunning gypsum evaporite deposits. We met up with Mick our birding friend on the way to the first stop, had a coffee at the Cuevas de Sorbas and then walked up the Rambla del Infierno to the cave at the far end (picture). Plenty of discussion on the way which continued in Sorbas Rambla and road cut and the Rambla de Gochar before calling in at the Centro de Visitantes Los Yesares in Sorbas where after David and Ted had spotted them we were lucky enough to get hold of half a dozen super (free!) booklets: Geology of the Arid Zone of Almeria ISBN 84-933537-0-1 which we distributed around the cars.

Having done a basin on Day 1, Day 2 was a ‘sierras’ day – the Sierra de Alhamilla in this case. We started off though with a visit to Cerro del Joyazo, the ‘garnet volcano’ east of Nijar. The service road along the A7 has been much improved and well graded so there was only about 0.5 km of rougher track. Last winter’s rains seemed to have washed out plenty of garnets – there were lots of pink patches in the sand on the track in and we also managed to find a lot of cordierite (this is original type locality of the blue crystalline version discovered by Cordier), sillimanite and lower crust xenoliths material (picture) of black and white gneiss with garnet, cordierite and sillimanite porphyroblasts. After last June’s recce we had high hopes of the Níjar-Lucaiñena traverse across the S de Alhamilla and it started well with the basin and Alpujárride stops and the first of the Nevado-Filabride exposures. Lunchtime also gave us a sight of a Montpellier snake but though Mick chased it up the bank he wasn’t able to catch it to give us a closer look. Sadly though after that the local highways people have now put up crash barriers effectively cutting off access to all our carefully noted parking places. I particularly regretted one super N-F exposure where we had observed a visible increase in garnet phenocryst size as we walked up the hill away from the thrust area.
A bonus was that we found we were able to park at the fault zone on the northern edge, and a second bonus was that the track from Rambla Hondo down to Polopos, along the route of the old mineral railway, had been surfaced. The mineral railway itself must have been the target of a conservation project over the winter: the route has been tidied up, fences erected on the more exposed stretches, and information boards added.

We wound up the day, which turned out the be quite a long one, with a visit to the Brèche Rouge at Playa del Algorróbico (twinned amphibole crystals in dacite - see right), the unaltered cores at the mirador where a wildlife bonus was a group of 5 ibex for whom we were obviously objects of curiosity as they stayed on top of the cutting for some time looking down at us (picture, left)

Finally we stopped to look at the Carboneras-Sopalmo fault zone which was looking good in the evening sun with the Tahel schist on the left, and multicoloured Alpujárride rocks in the centre with volcanic on the right. Unfortunately we had run out of time to visit it, though our recce had shown the road down was fine with a good surface on the steep section below the village.