Girvas Paleovolcano

The Suna at Girvas was dammed in the 1930s for hydroelectricity and its old bed left dry, and what the water had been covering turned out to be the eroded remains of a volcano that erupted around two billion years ago in the Palaeoproterozoic - among the oldest volcanic structures anywhere that can simply be walked onto. What is visible is the vent area and the lava flows around it: layered basalt in successive sheets, pillow structures formed where lava met water, columnar jointing, and the pothole-scoured channel the river cut through it all before the dam. It is unusual to be able to stand inside a structure of that age without any interpretation between you and the rock. There is no infrastructure to speak of - a path down from the road and the dry bed - and when the dam spills, which happens in high water, the site floods and cannot be entered.

What you'll find

• The vent - the eroded core of a volcano that erupted around two billion years ago.
• The lava sheets - layered basalt flows with pillow structures and columnar jointing.
• The dry bed - the Suna's old channel, emptied by the 1930s hydro dam.
• The accessibility - a two-billion-year-old structure you can walk directly onto.

When to go

May to September. One to two hours. Check the dam - when it spills the riverbed floods and the site is inaccessible.

Before you go

The site floods without warning when the dam releases water, and people have been caught out. Rock is uneven and slippery when wet. There is no signage or interpretation on site. Nothing looks dramatic without knowing what you are standing on.

Nearby

Kivach waterfall is south-east; the Marcial Waters spa is nearby.