Wealden District and the Bas Boulonnais. 21 



ing one in the escarpment. I have observed the temperature of a considerable 

 number of springs of this description, and have found it, at different times of the 

 year, to be uniformly about 51° or 52° Fahr. These springs seem strongly confirma- 

 tive of the existence of transverse dislocations, of which they would be almost the 

 necessary consequences. 



Transverse River-courses through the Greensand Escarpment. — In the transverse 

 valleys just described, we may probably recognise the earliest stage in the formation 

 of those large transverse valleys which have resulted from the removal in such 

 places of the whole escarpment of the greensand, and through which the transverse 

 drainage of the district takes place. One of these is opposite Guildford, and another 

 near Dorking. The wider these valleys are, the less likely are they to afford present 

 indications of any transverse dislocations in which they may have originated. In 

 neither of these cases have I been able to recognise direct proofs of such origin. 

 Our conclusions respecting them can only, therefore, rest on analogy. 



There is also another curious case of a transverse river-course, opposite the 

 western extremity of the Hog's Back, where the western branch of the Wey, in- 

 stead of pursuing what might appear its natural course at the foot of that hill, cuts 

 directly through the greensand ridge west of Cooksbury Hill. It seems to have 

 an obvious connexion with the change of structure which is observable between 

 the chalk ridge just mentioned and Farnham. I have already stated that the dip 

 towards the western end of that ridge is not less than 70° or 80°, whereas at 

 Farnham it is not more perhaps than about 10°. This change accounts for the 

 sudden termination of the ridge, and indicates moreover a transverse curvature, 

 such as must almost necessarily be accompanied by a transverse fracture, which, 

 continued in a direction exactly south from thence, would account for the actual 

 and apparently anomalous direction of the river-course as above described. 



West of the supposed transverse fracture just mentioned, the Guildford line loses 

 its distinct character. I doubt its continuance much to the west of Farnham. 

 Near that place I believe considerable disturbance is indicated by subterranean 

 water-courses, but I could detect no conclusive external evidence of a line of curva- 

 ture or anticlinal line beyond that place. Mr. Martin's Pease Marsh line, however, 

 somewhat south of the former, seems, as it approaches the chalk westward, to 

 assume a more determinate character than I conceive it to have nearer Guildford. 

 Towards the east I have shown that the Guildford line extends to Tilburstow Hill. 

 Immediately east of that hill is another break through the greensand escarpment, 

 to the east of which we find a line of elevation, which I shall now proceed to de- 

 scribe. 



Seven Oaks Line. — This line was first noticed by Dr. Fitton in his memoir " On 

 the Strata below the Chalk." He traced it from Montreal Park to a point between 



