This hill is the remainder of a glacier scraped dolomite shield volcano, covered with boulders, which make the 7-8 km long drive across it rather slow and bumpy. On its top a large and a 100 m deep cauldron, partly filled with sand, suddenly opens up. East of the hill is a 20 km wide alluvial plain, where travellers have to drive for kilometres on end in the rather shallow, but fast flowing water, which keeps the sand in constant movement and makes the crossing very tricky and difficult for the inexperienced.
The only way to cross the alluvial plain, when the meltwater rushes across it, is to select the low drive and the lowest gear and simply continue without ever hesitating or stopping on the way through. When the area is dry and the wind blows, sandstorms make the crossing hazardous and difficult. Then the GPS or the compass come in handy.
Close to Urdarholl is the Holuhraun Lava field that emerged north of Dyngjufjoll from Volcanic eruption in 2014.