Icebergs
floating out to sea. They are the source of the "ice-rafted debris" found
in cores. Note the one on the left black with debris, probably
volcanics.
A source for volcanic glass in Iceland. This is the head
of a fjord with basalt created by one of Iceland's many eruptions. When
this fjord again becomes glaciated, the bergs that break off and float out
to sea will be laden with volcanic debris.