Distiihution of Rocks 37 



to rock but with special characters influencing the vege- 

 tation (see Chapter XIII). 



A detailed account of the distribution of British soils 

 ■would be out of place in this book, even if the necessary- 

 data, which would have to be derived from a systematic 

 soil-survey, were available. But some account of the 

 general distribution of soils in relation to the geological 

 formations may be given. 



As we have already seen (p. 17) the east and south-east 

 General dis- ^^ England, as well as much of the Midlands, 

 tribution of are entirely composed of Secondary, Tertiary, 

 geological post-Tertiary and Recent deposits, while the 



formations. north, west and south-west, ^\'ales, and 

 nearly the whole of Scotland and Ireland are formed of 

 metamorphiCj Palaeozoic, and intrusive igneous rocks. 

 Yery considerable areas of these older rocks however, 

 especially in Scotland and the north of England, as well 

 as some of the newer ones in the Midlands and east, are 

 covered by deposits of glacial drift left by the retreating 

 ice. This drift may form a heavy "boulder clay" or it 

 may be sandy or loamy. 



The archaean and Palseozoic rocks and the igneous 

 formations of various ages, include all the hardest rocks, 

 and they have been far more elevated and folded by earth- 

 movements than any of the later ones. For these reasons 

 they form all the mountainous land in the country, while 

 the more recent formations, including the glacial deposits, 

 are for the most part comparatively soft and yielding, 

 have been but little elevated or disturbed, and form flat 

 or undulating plains broken only by ranges of low hills. 

 Many of the hard older rocks, such as limestones, 



„ ., ^ . . sandstones, flags, slates, etc., and also many 

 Soils denved ' ,_? ' ' . ., . •' 



from rocks ot the crystailme, metamorphic and igneous 



of different rocks, weather with difiiculty, and conse- 



^^^- quently form very shallow or comparatively 



