Start your hike from the parking lot by highway 54, where you enter into the forest reserve through a stainless steel gate. You will hike through some low birch forest and lupine until you cross the fence. Now there is a steep and coarse rhyolite scree in front of you. This is a debris avalanche created during collapse of the mountain´s summit. This avalanche probably occurred shortly after the end of the ice age, ca. 10 thousand years ago. The trail is up the debris flow deposit, composed mainly of blocks of rhyolite, dacite and occasional obsidian fragments. Continue up until you reach Skál, the valley at the base of the vertical cliffs. The cliffs are composed of rhyolite and dacite lava flows from the late Tertiary period, about 4 million years ago. In between the lavas there is a thick layer of rhyolite ash, which is turning to clay. The cliff is therefore resting on clay and consequently very unstable. More rock falls are likely in the future. Exit the Skál valley to the west and climb up the ridge to the right. Now you hike along the west flank of the mountain, diagonally up to the top marked V1 on the map. This is not the highewst point, however. Continue up to the high summit, which is also composed of rhyolite that is severely flow-banded. Enjoy the view from here in all directions. Notice the little hill to the south, with an obvious cross in its center made of grass. Just to the west of the summit there is a secondary top composed of black and well jointed basalt. This peak is Nónhnúkur and it is a volcanic plug, that is much younger than the rhyolite below. This basalt contains somve very beautiful, large and black shiny crystals of the mineral pyroxene. The trail down follows the eastern flank of the mountain. Then you wil come across an 80 meters long and 1 meter wide fissure in the mountain, cutting across the rhyolite. This fissure is parallel with the cliff below. This is probably an indication that the top is ready to break off again, to form another debris avalanche. So, do not tarry here for too long. Continue down the ridg on the right and in the direction of lake Vatnsdalsvatn and to the parking lot to close the circle.