GEOLOGY OF HERTFORDSniKE. 159 



trouble and expense in draining than in those soils which rest upon 

 the chalk. Hinxworth, indeed, has long been known to all 

 readers of agricultural literature as the site of the mixed system 

 of drainage carried out by Mr. Bailey Denton.*' 



The Gault is often called the Oak-tree Clay, and certainly the oak 

 thrives better in this part than anywhere else in the county, and 

 from the summit of the chalk escarpment the outcrop of this 

 formation is otten visible as a line of densely-wooded country. 



The true agricultural character of tlie Gault soils is best seen in 

 the neiglibouring county of Buckinghamshire, whei'e the land over- 

 lying this formation is a cold, wet soil, most expensive to cultivate 

 as arable land, and therefore chiefly in pasture. In our own county 

 this character is destroyed by the extensive alluvial drift which 

 covers its surface. 



Y. The Ecoxomic Pkoducts of Heetfordshihe tjsefttl ix 



Ageicultijee. 



It may generally be noticed that an advanced state of agriculture 

 not only does not coincide with grand features of scenery, but also 

 is usually inversely proportional to the mineral importance of a 

 district. We shall not, therefore, expect a long list of economic 

 products from the rocks of our own county. 



From the strata below the Chalk there is little that can be con- 

 verted to practical utility, except perhaps the firestone of the Upper 

 Greensand and the phosphatic nodules (coprolites) which occur at 

 the bottom of the Chalk-marl. These coprolite-beds are worked 

 near Lilley Hoo, and at various places between Hitchin and 

 Cambridge.! 



From the Chalk many useful products are obtained. The 

 flints are largely used for road-metal and for building purposes ; 

 and, when burnt and ground, they can be employed for pottery 

 admixtures. The chalk itself is extensively burnt for lime, and to 

 the many pits excavated for this j)urpose geologists are indebted 

 for many interesting sections of this formation. It is also used a 

 great deal in some districts for chalking fields, its addition being 

 considered a great improvement in heavy soils. Chalking is a very 

 old custom in Hertfordshire. Its chief merits depend upon its 

 mechanical effect upon the soil, but it is said also to assist in 

 destroying troublesome weeds, such as may- weed and sorrel. Its 

 eflPects, too, are lasting, and the process seldom needs repetition 

 during the same tenancy. At the top of the Chalk-marl is a bed of 

 sandy limestone, which is sufficiently hard to be used as a building- 

 stone. This band, called the Totternhoe stone, may be traced from 

 Tring by Miswell, Marsworth, Pirton, and Cadwell, to Ashwell. 

 It is used in St. Albans Cathedral, in some of the older parts of 

 Windsor Castle, and in many churches in the county. When 



* See ' Jonm. Royal Agric. Soc.,' vol. xx, p. 273. 



t See Clutterbuck on " The Coprolite Beds at Ilinxworth," ' Transactions of 

 the Watford Nat. Hist. Soc,' Vol. I, p. 238. 



