GEOLOGY OF UEUTFOKDSHIRE. 161 



VI. Stjmmart and Conclusion. 



In the foregoing imperfect description of the chief agricultural 

 features of Hertfordshire, we have been able to assign geological 

 causes for the prevailing industries which characterise each district. 

 "\Ve have seen tliat the hay-farms on the heavy soil of the south, 

 overlying the London Clay, give place to the market-gardens and 

 nurseries of the t'ertile alluvium of the valley of the Lea; while, 

 still further towards tlie cast, the character of the soil is so changed 

 by the presence of the chalky boulder-clay, that arable culture 

 predominates, and a large malting industry has sprung up upon one 

 of the best barley-soils in England. The same geological characters, 

 also, which have combined to stamp the northern part of the 

 county as a wheat-growing district, have also been the means of 

 establishing an important industry in the manufacture of straw- 

 plait, the main source of the wealth of the districts around Luton 

 and St. Albans. 



But still another feature of interest is presented to us, when we 

 compare our county with other districts, similar in their main 

 geological features. For the purpose of assisting in this comparison 

 I have calculated the percentage acreage devoted to each crop, as 

 well as the proportion of permanent pasture, bare fallow, orchards, 

 market-gardens, woods, and nurseries in the twelve south-eastern 

 counties which bear the closest geological resemblance to Hertford- 

 shire. These calculations have been based upon the Agricultural 

 Eeturns for 1881, issued by the Board of Trade. 



An examination of this table will show that, of these twelve 

 counties, only two, viz., Cambridgeshire and Wiltshire, have a 

 larger percentage of land devoted to agricultural puiposes than 

 Hertfordshii'e ; while Hertfordshire ranks with the eastern counties 

 generally as the largest corn-growing district in England, a position 

 which it owes almost entirely to the nature of its drift-deposits, 

 and to the comparative dryness of its climate. We have seen that 

 it is to these drift-deposits that we owe the generally heavy nature 

 of our soils. In fact, if we briefly survey the distribution of the 

 glacial drift in the eastern counties, we find that in JSTorfolk there 

 is a comparatively small area of clay, and that is chiefly the chalky 

 boulder-clay. In Suffolk the area covered by this clay is larger 

 than in Norfolk, while in Essex and Hertfordshire, in addition to a 

 comparatively large area of boulder-clay, there is also a considerable 

 district of stiffer London Clay. The land in fact becomes stifter 

 from north to south, the soil of Hertfordshire being on the whole, 

 however, not quite so stiff as that of Essex, both on account of the 

 chalk soils of the north, and the lighter nature of the superficial 

 deposits in some of the western portions of the county. 



The influence of this change of soil is well shown by the table 

 (p. 162). Clover and other rotation grasses decrease towards the 

 south, being 15-1 in Norfolk, ITl in Suft'olk, and only about 10 

 per cent, in Hertfordshire and Essex. The proportion of bare 

 fallow, also, an unmistakeable index of heavy soils, increases largely 



