The agate of the Bay of Fundy occurs primarily in veins in the basalt lava of the North Mountain formation, an extensive flow system which erupted some 175 million years ago as the supercontinent Pangea rifted apart. Although you will find nodular agate in some places (notably in the area around Scots' Bay) - in a general sort of way Bay of Fundy agate tends to occur in veins. These, harder than their enclosing rock, weather out during winter's frost thaw cycles and are collected on the beaches as flattish plates. Since agate forms from the walls of the vein toward the center patterning is often symmetrical. While agate patterning is immensely variable, in a general sort of way we can say that Bay of Fundy agate comes mostly in the "three P's" illustrated above: panorama plume and porcelain. Click on the pictures for larger images.