SE Rauðufossafjöll - the best-exposed and best-studied rhyolite tuya at Torfajökull. The flat cap is composed of subaerial lava flows, which overlie poorly-consolidated fine-grained ash (concealed by scree). Lava bodies on the tuya flank are cut by near-horizontal columnar joints and appear to have flowed within steep-walled cavities melted in the glacier base.

This image was provided by Hugh Tuffen, Lancaster University.

References

Tuffen H (2001) Subglacial rhyolite volcanism at Torfajökull, Iceland. Unpublished PhD thesis, Open University, UK.

Tuffen H, McGarvie DW, Gilbert JS, Pinkerton H (in press) Physical volcanology of a subglacial-to-emergent rhyolitic tuya at Rauðufossafjöll, Torfajökull, Iceland. Journal of the Geological Society of London special edition: Volcano-ice interaction on Earth and Mars (ed. J.L. Smellie).