Earthwatcher's photos with the keyword: pillow lava

Pillow lavas of the Porth Maenmelyn Volcanic Formation (Ordovician, Llanvirn age) are well exposed adjacent to the Pembrokeshire Coastal Path just above and to the north of the eponymous bay. These pillow lavas were formed by a submarine eruption, probably in an island arc setting, probably in not particularly deep water. The southerly dip (to the right in the photo) is mostly due to subsequent uplift and folding.

This is a view of the Ordovician age pillow lavas on Strumble Head, Pembrokeshire. Pillow lavas are formed when molten basalt lava is erupted onto the sea floor. If the water is deep enough, the hydrostatic pressure stops the lava from exploding the sea water into steam. Instead, the liquid rock and liquid water co-exist together in an uneasy truce. The lava is extruded like toothpaste into successive oval globules, resembling pillows or sacks, hence the name. See the video clip here: oceanexplorer.noaa.gov/explorations/04fire/background/vol...

The Strumble Head lighthouse is located on Ynys Meicel ('Michael's Island') which itself is composed of the Strumble Head Volcanic Formation, mainly pillow lavas.

Another photo of the Ordovician age pillow lavas on Strumble Head, Pembrokeshire; a close-up view of one of the pillows. Radial cracking/jointing is visible, as is a hint of a finer-grained chilled margin on the edge of the pillow. Pillow lavas are formed when molten basalt lava is erupted onto the sea floor. If the water is deep enough, the hydrostatic pressure stops the lava from exploding the sea water into steam. Instead, the liquid rock and liquid water co-exist together in an uneasy truce. The lava is extruded like toothpaste into successive oval globules, resembling pillows or sacks, hence the name. See the video clip here: www.youtube.com/watch?v=y7CtJNO14YI

Another view of the Ordovician age pillow lavas on Strumble Head, Pembrokeshire. Pillow lavas are formed when molten basalt lava is erupted onto the sea floor. If the water is deep enough, the hydrostatic pressure stops the lava from exploding the sea water into steam. Instead, the liquid rock and liquid water co-exist together in an uneasy truce. The lava is extruded like toothpaste into successive oval globules, resembling pillows or sacks, hence the name. See the video clip here: www.youtube.com/watch?v=y7CtJNO14YI

A general view eastwards over the pillow lavas on Strumble Head, Pembrokeshire. Can you spot the seal?

Another photo of the Ordovician age pillow lavas on Strumble Head, Pembrokeshire. This photo shows the slaggy texture of the pillows. Unfortunately no scale as this particular exposure was not readily accessible to allow the placing of the lens cap or similar. However, the individual pillows are around 20 cm - 40 cm long. Pillow lavas are formed when molten basalt lava is erupted onto the sea floor. If the water is deep enough, the hydrostatic pressure stops the lava from exploding the sea water into steam. Instead, the liquid rock and liquid water co-exist together in an uneasy truce. The lava is extruded like toothpaste into successive oval globules, resembling pillows or sacks, hence the name. See the video clip here: www.youtube.com/watch?v=y7CtJNO14YI