The Humber is created by the confluence of the River Ouse and the River Trent. The longships now navigate their way up the river Ouse. The oarsmen would often lay the oars (made from pine) over the top strake, rather than use the oar holes. In the top border appear two closely related Viking symbols; the triquetra and the triskelion. The triquetra symbol is made from three interlocking arcs and appears on the Viking silver penny of Olaf Sihtricsson minted between 941 and 944. The Triskelion comprises of three interlocking horns and in Norse mythology symbolizes the mead of poetry and wisdom. This symbol appears on the 9th Century Snoldelev rune stone in Denmark.