Just noticed that today is the proposed International Volcano Day: enjoy Montaña Negrita bends/Curvas del Pastel/La Tarta, interbedded mafic scoria and phonolitic tephra from separate sourdes, Tenerife's Dorsal Ridge.
Visited every OUGS #VolcanoesOnAShoestring trip
Do you have a favourite volcano?
Ignimbrite is a fairly strong, low density, easily worked freestone. Up close you can see the lithic and pumice clasts but it does rather resemble breeze blocks from a distance! Not sure about the pointing though....
The Arico Ignimbrite is one of the few welded ignimbrites - look for the fiamme - clasts flattened while the volcanic tephra were still hot and plastic
Not exactly #urbangeology as some is rural! But it is building stone...
On #OUGS Tenerife trips #VolcanoesOnAShoestring looked at building stone use as a sideline. Here's some ignimbrite, unwelded (L) and welded, uncommon on the island (R). See ALT text for more detail.
More to follow ...
The syenite texture with those randomly orientated, thin laths of feldspar reminds me of syenite I've seen on Tenerife and Fuerteventura. #OUGS #VolcanoesOnAShoestring 1990s/2000s/2010s
Tindaya in the centre is a trachyte volcanic plug
#MountainMonday Tindaya, Fuerteventura, is a Majo sacred site and, unusually on the island, a trachyte volcanic plug which stand out from the surrounding basalt hills because of its pale colour. #VolcanoesOnAShoestring 2010s
#VolcanoThursday Volcàn de Bayuyo, Fuerteventura, a monogenetic cone that erupted some 10 000 years ago. #OUGS #VolcanoesOnAShoestring 2010s
#VolcanoThursday penitentes near Teide top teleferico station. Tenerife #VolcanoesOnAShoestring #OUGS
Hydrothermally altered Miocene volcanic ashes and breccias on the edge of the Rodalquilar caldera, Las Negras, Almeria, Spain.
#VolcanoThursday #OUGS #VolcanoesOnAShoestring
Chinyero lies on one (the northwesterly) of three ridges emanating from Teide, Tenerife's central volcano. A single eruption lasting a week or so built up a scoria cone and produced an aa flow.
#VolcanoThursday The most recent eruption on Tenerife: the monogenetic scoria cone of Mta Chinyero (1909). There's been seismic activity on that ridge since, but no more eruptions. #VolcanoesOnAShoestring #OUGS
#VolcanoThursday the eroded remnants of Fuerteventura's southern shield volcano, in Spain's Canary Islands. Talus cones around the base are coated with sand and dust from the Sahara Desert blown across to the islands by the easterly "calima" wind. #OUGS #VolcanoesOnAShoestring
Steep, bare rocky hillside: orange/brown/purple volcanic rock with retamar bushes. Geology students in shorts and T shirts climbing a narrow path towards an area of blue-green mineralisation. March 2003
#mineralisation to brighten up a Monday morning. At the southern end of the Roques de Garcia (Tenerife) my #VolcanoesOnAShoestring group walking up from the Ucanca caldera to Los Azulejos. Stunning green-blue and cream coloured alteration to clay minerals
