156 J. V. ELSBEN AGRICULTURAL 



springs, might be facilitated by the construction of artificial 

 swallow-holes. 



The Chalk Bistrict. — Prof. Prestwich says of this area:* " The 

 chalk hills which bound the Tertiary area on the north, unlike the 

 chalk of Salisbury Plain, present but a small extent of open downs, 

 and are well wooded on their summits. This arises in part from a 

 covering of clay-drift, and in part from thin cappings of the Lower 

 Tertiary beds." "VVhitaker also says:f "In the north-western 

 corner of our district, in Bucks and Herts, there is absolutely no 

 down-land, and the greater part of the tract consists of ploughed 

 land diversified by woods and parks." The only portion of the 

 county, indeed, which can be said to have agricultural features at all 

 characteristic of the Chalk formation, is the narrow strip forming 

 the Eoyston and Dunstable Downs. Here, although sheep-farming 

 is the characteristic feature, yet much corn is grown, and the 

 quality of the straw grown on these chalk soils is so suitable for 

 the manufacture of straw-plait, that an important industry has 

 sprung up around Dunstable and Luton, and a considerable market 

 for the sale of wheat-straw has been established at Hitchin and 

 other places in the northern part of the county. Of this district 

 it has been said:^ "The strip of thin chalk-land crossing the 

 northern part of the county, with its wide, open fields, and turnip- 

 and sheep-farming, is so suggestive of Cambridgeshire that the 

 boundary of the counties at Eoyston may well be passed without 

 being remarked. The natural division is found in the hills near 

 Therfield, on the great North road, when you plunge at once into 

 Hertfordshire proper, with its woods, small enclosures, and heavily 

 timbered fences." 



To the south of this narrow strip of chalk-soil, however, the 

 nature of the underlying rock is completely concealed by the heavy 

 clays which cover its surface, the district drained by the Beane, 

 Rib, and Ash being uniformly covered by loamy clay, derived 

 chiefly from the upper glacial drift ; while the western portions of 

 this area are occupied by a flinty loam, which seems in places to 

 consist almost entirely of stones, and which generally corresponds 

 to the " clay-with-flints " previously described. Thus, although 

 there appears to be a gi'eat mixture of drift-soils over the portion 

 of the chalk area which lies between the Eocene beds in the south 

 and the high ground in the north, important differences may be 

 established between the eastern and western halves of the county ; 

 for, while the soils of the eastern boulder-clays are heavier in 

 character, and more calcareous, they are to a great extent free from 

 that abundance of flints which especially characterises the north- 

 western corner of the county. Some of the worst land of the whole 

 district lies towards the east and south-east of Stevenage, where 

 the clay forms so bad a soil that it cannot easily be improved, 



* ' Quart. Joum. Geol. Soc.,' vol. x, p. 19. 

 t ' Guide to the Geology of London,' p. 21. 



X Evershed, "Agriculture of Hertfordshire," ' Joiirn. Eoy. Agric. Soc.,' 

 vol. XXV, p. 271. 



