These were made in the Borre style with characteristic powerful faces and prominent eyes. They are Petersen Type 51 brooches and are described in Ingmar Jansson's 'Oval Brooches, 'A Study of Viking Period Standard Jewelry', Upsala Sweden, 1985.  The Borre art style was popular during the 9th and 10th centuries. Open spaces in the brooch surface appear near the end of this period. 

These are single shell brooches where the originals were double shelled.