98 The Geology of the Roihray Line from 



From an agricultiixal point of -view the lower elialk is notaMe as 

 fomiing the principal arable land of the district, and the heavier 

 land of the chalk area, except for the clayey soil over the upper chalk. 



Between Chiseldon and Yatesbury it has an outcrop of from three 

 to four miles. It also forms the lower part of the chalk escarpment 

 and is a prominent feature. 



Arr/ireohgy of the Lower Chalk. 



Tliis escarpment of the lower chalk has numerous old trackways 

 cutting- deej)ly into it, probably dating back to the Stone Age. These 

 trackway's lead down to the belt of woodland at the base of the 

 escarpment, in these woods game no doubt abounded. The 

 number of these is in marked contrast with that of the modern 

 roads, which are here few and far between. This points to a popu- 

 lation in early days much more niunerous than the scanty numbers 

 now inhabiting the district. 



Canyons and Terraces in the Loiccr Chalk. 



Near the edge of the lo-\A'er chalk escarpment may be seen — as, 

 for example, near Liddington and Wanborough — steep-sided 

 canyon-shaped valleys looking like chasms rent in the chalk. 

 These are the result of water action in former times, wlien the 

 water-level in the chalk was higher than now ; the draining of the 

 Wliite Horse Vale, the clearing of the waterways, the cutting 

 down of the woods, and the diminished rainfall, has caused this 

 lowering of the Avater. So steep are the slojies of these valleys that 

 you come on them from the higher ground quite suddenly and 

 without preparation. Tlieu* bottoms are now dry, and in many 

 cases I have found old pit-dwellings and lynchets or cidtivation 

 terraces, connected with them. Other good exam^iles may be seen 

 at King's Play Hill and Heddington. Here the sides of these 

 valleys are teiTaced and their bottoms flat — valleys that were 

 originally v-shaped having been flattened at the bottom by the 

 action of constant ploughing, continued to the present day from 

 the time when the terraces were cultivated. 



The lower chalk, including the chalk marl, is about 250ft. thick, 



