gloppedalsura magma geopark stavanger norway

100 altitude annual area avalanche away boulders burrowed byrkjedal byrkjedalsgryta consists course covered cycle dammed debris evidence expanding forced formed former frost geopark gilja giljajuvet gloppedalsura gully hunnedal ice lake magma massive melted metre moraine mountainside norway number outlet period piled river rocks scree settled sheet southern stavanger terraces thick time towards veen vikesayen water were