SUMMARY OF SUBJECT 27 



and corn-fields. He has replaced some parts of the 

 primeval forest by plantations of a different type, 

 wherein the native hardwood trees are mingled now 

 with larch, silver-fir and other trees which seem to 

 have had no place in the original flora. 



But the minor modifications of the landscape within 

 historic time have not been merely those due to 

 human interference. Nature has been ceaselessly at 

 work in slowly, and for the most part imperceptibly, 

 changing the forms of the ground. The streams 

 have dug their channels deeper into the flanks of 

 the hills and have spread their alluvial soil further 

 and wider over the valleys and lake-floors. The 

 frosts of winter have been splintering the crags, the 

 springs have been sapping x the cliffs, and from time 

 to time landslips have been launched into the stream- 

 channels below. The sea has cut away large slices 

 of land from some parts of the coast-line, while to 

 others it has added strips of alluvial ground and 

 mounds of shingle. We have seen too that under- 

 ground movements have contributed to modify the 

 landscape in some parts of the country, certain tracts 

 having been upraised so as to expose broad spaces 

 of flat ground, while others have been submerged 

 beneath the sea which now ascends into what were 

 formerly open valleys. This sinking of the land in 

 southern England, inasmuch as it helped to separate 

 Britain from the continent, must be regarded as prob- 

 ably the most far-reaching change that has affected 

 the landscape of this country since the days of Neo- 

 lithic man. 



