A post in Frans-Arne Stylegars excellent blog «Arkeologi i nord» on nordic archeology, documents an horg (old-norse Hǫrgr, i.e. stone-altar) on the farm Ersdal in Flekkefjord. The text is in norwegian but the pictures are not :)

http://arkeologi.blogspot.com/2009/07/horg-pa-ersdal-i-bakke.html