Þingvellir (Thingvellir) is a historic site and national park in Iceland, east of Reykjavík. It's known for the Alþing (Althing), the site of Iceland's parliament from the 10th to 18th centuries. On the site are the Þingvellir Church and the ruins of old stone shelters. The park sits in a rift valley caused by the separation of 2 tectonic plates, with rocky cliffs and fissures like the huge Almannagjá fault.
Hverfjall is a tephra cone or tuff ring volcano in northern Iceland, to the east of Mývatn. It erupted in 2500 BP in the southern part of the Krafla fissure swarm. The crater is approximately 1 km in diameter.