Storms can be a boon for beachcombers, bringing not only driftwood and seaweed but occasionally semiprecious stones to British shores. Amber, a fossilized tree sap dating back more than 35 million years, is common in the Baltic but rare in Britain. However, after being transported by rivers and glaciers, amber lies trapped in boulder clay at the bottom of the North Sea. Bad weather churns up the seabed, erodes the clay, and shifts the amber, which eventually washes up in England. The area between Felixstowe and Southwold in Suffolk is known as the amber coast for the number of pieces found there after spring gales.
Jet, another tree remnant more than 180 million years old, is formed by the fossilization of waterlogged wood in sea mud. Storm wave action uncovers and transports submerged jet to the shoreline. Violent storms and high tides often bring pieces of jet ashore on the North Yorkshire coast near Whitby.
In both cases, this movement occurs because, owing to their organic origin, amber and jet are about half as dense as purely mineral stones such as quartz. While heavier stones are left behind, fragments of jet and amber can be dragged along by underwater currents and washed up for lucky treasure hunters to find.
