The differences of salinity support this method, and, especially in the northern European seas, often prove a sharper criterion of the boundaries than temperature itself; this is especially the case at the entrance to the Baltic. Evidence drawn from drift-wood, wrecks or special drift bottles is less distinct but still interesting and often useful; this method of investigation includes the use of icebergs as indicators of the trend of currents and also of plankton, the minute swimming or drifting organisms so abundant at the surface of the sea.
These are no longer cast but hammered into shape, and decoration is elaborate curvilixear rather than simple rectilinear, the forms and character of the ornamentation of the northern European weapons resembling in some respects Roman arms, while in others they are peculiar and evidently representative of northern art.
The currently favored crop under northern European conditions is willow grown as short rotation coppice.
European discount cruises can make the wonders of Venice, the Greek islands, Barcelona, and other popular ports along the Mediterranean Sea and northern European shores much more affordable.
Mediterranean cruises, for example are often more expensive than Northern European cruises because the Mediterranean is more popular with tourists.
