Page:VCH Bedfordshire 1.djvu/78

 A HISTORY OF BEDFORDSHIRE and still fewer bogs, remain. Bedfordshire has neither any large expanses of water such as the East Anglian broads, with their interesting aquatic vegetation, nor any rocky escarpment on which a rupestral flora could grow, as in the Derbyshire dales ; indeed the limestone of the Great Oolite only comes to the surface in small and widely separated patches, and were it not for the long line of the Chalk escarpment, and the elevations of the Greensand at Woburn and Sandy, the flora would possess but few species of an attractive character. In the few pages allotted to this subject it is desired to give the salient features of the county botany and to show how they compare with those of some of the border- ing counties. In its general character Bedfordshire has much in common with the botany of Buckinghamshire and Hertfordshire, since the dominating feature in each is the long range of the Chalk hills, and the picturesque escarpment of the Lower Greensand about Woburn also extends into Buckinghamshire. As there is no sea coast, there is, with the exception of a few casuals, no maritime flora. The physical character of the county is very varied for so small an area, but for botanical purposes the geological formations offer naturally two main divisions which are not dispropor- tionate in size. Putting it briefly, the northern division is clay, with a river valley of alluvium, gravel and limestone ; the southern division has a lighter soil, which in turn falls into two divisions, Greensand and Chalk, with a slice of Gault sandwiched between them. In the following obser- vations the terms northern and southern divisions will denote these geological characteristics. In the north most of the hills are capped with Boulder Clay, which also forms a broad patch between the windings of the Ouse. The Oxford Clay comes to the surface south of the county town as far as Lidlington, where it is succeeded by the Lower Greensand. Following the course of the Ouse, besides the gravels and alluvium there are exposures in bands of Oolitic limestone and Oxford Clay and Cornbrash — the latter forming a persistent bed of slight thickness and about a quarter of a mile wide. The Lower Greensand enters the county at Leighton Buzzard and crosses it about mid-way. Aspley Guise, Lidlington, Millbrook, Haynes, Southill, Sandy and Everton are on its northern edge. At Leighton, Heath, Tingrith, Pulloxhill, Silsoe, Campton, Shefford, Eyworth and Potton, the Greensand is contiguous with the Gault, which extends in a narrow band from Eaton Bray on the south-west to Arlesey on the east. Along the line of contact the surface soil is often of a mixed character, chiefly owing to farming operations. The Lower Chalk suc- ceeds the Gault at Dunstable, Eggington, Chalgrave, Toddington, Harl- ington, Hexton, Stondon, Arlesey and Stotfold. The Chalk without flints is well developed in the south of the county. A flora typical of the Chalk is found on the downs of Luton and Dunstable, and the characteristic orchids are plentiful in those localities but are not confined to them. The bee {Ophrys apifera), the fragrant (Habenaria conopsea), 38