CHAP. IV TERRESTRIAL ERUPTIONS 51 
among the great Tertiary basaltic plateaux which cover so large an area in 
the north-west of Europe. Not only has no trace of any marine organism 
been found among their interstratified sedimentary, layers, but they have 
yielded a terrestrial flora which is preserved in hollows between the 
successive sheets of basalt. A full account of these rocks will be given in 
Hook VIII. 
