Mt Trolladyngja (4,815 feet) is a vast shield volcano at the northern end of the wide volcanic ridge Dyngjuhals, which connects the Grimsvotn and Bardarbunga central volcanoes.  This shield volcano is the biggest of the country, 6 miles in diameter with a 4,620 feet long, 1,650 feet wide, and a 330 feet deep crater on top.  Lava flowed from it in all directions, especially to the west and north.  Most of the lava field Frambruni was probably created by one of its eruptions, and also the lava field in Valley Bardardalur, which continues to the Thingey Area between two branches of River Skjalfandi.  The new Gaesavotn Route passes through the desert north of it, a 4wd track very rough on the tires of the passing vehicles.
Pic.: Dyngjuhals & Trolladyngja