There are quench features at Slag Hill, which is suggesting that the volcanic activity was subglacial. Slag Hill was formed throughout the Pleistocene period, but its most recent volcanic activity produced a lava flow on its western lobe that shows no evidence of ice-contact volcanism.
Quench features at Slag Hill imply subglacial volcanic activity. Slag Hill formed during the Pleistocene and experienced its latest eruption, which produced a lava flow on its western side without any indication of ice contact.