Sammendrag
An eight-point Rb-Sr whole-rock isochron from Caledonianrhyolites at Stord in western Norway defines an age of 455 +- 5 m.y.and an initial 87Sr\/86Sr of 0.7071 +- 0.00018. This places thevolcanism in the Upper Ordivicium, close to the Ordovician\/Silurianboundary.