By Andrew Alden
After a while the ice above the eruption melts into a lake, and the more explosive interactions of fire and shallow water yield mainly hyaloclastite. When the lake is filled or boiled away, lava flows more gently again, forming thick flows, often with columnar jointing that forms as the rock slowly cools. All of these stages are visible in Hjorleifshofdi.
The name tuya comes not from Icelandic, but from the Tuya region of British Columbia where many subglacial volcanic features have been described.