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as far as Alton. After the Wey has passed the chalk, it 

 diverges from its Northern course, towards the Mole, and 

 at one time it is possible that they may have united at 

 some point before joining the Thames, of course above the 

 present 200 feet contour. That some depression or combina- 

 tion of depressions which inclined the two rivers together 

 existed at this spot, or as appears likely does now exist, is 

 made the more probable by the abandonment of the 

 Thames of its more direct course, by Acton and Ealing, to 

 diverge Southwards by Chertsey and Walton ; and it may 

 be that the great quantity of debris which this conjunction 

 caused to accumulate, with a rise in the land and di- 

 minished rainfall, separated the streams again, and now 

 the gravel-capped St. George's Hill lies between, and still 

 the two rivers run on the proximate margins of the Hill. 



That part of the Wey, however, which lies Westward 

 of Pepperharrow, I believe formerly ran Northwards 

 through the gap or pass at Aldershot, and was the Weal- 

 den affluent of the Blackwater. This gap has its lowest 

 crest but a few feet below the 300 feet contour line, and 

 the streams which descend the greensand hills from the 

 South still incline towards the gap, while the course of the 

 Wey forms a deep valley between Farnham and Crooks- 

 bury Common, whose bounding hills exceed the elevation 

 of the lowest level of the Aldershot Gap by more than 100 

 feet ; which valley will also be seen to be inclined towards 

 the gap from the S.E. During some period when the 

 Blackwater valley was blocked, whether from debris, land- 

 slips, or ice, it is probable that the streams South of 

 Aldershot were dammed so high that the waters were 

 ponded back and found an outlet into the basin of the 

 present Eastern part of the Wey, and this might have 

 been assisted by some of the causes which contributed to 

 the depression on the Eastward, which produced the 

 approximation of the Wey, Mole, and Thames, near St. 

 George's Hill, and enabled the Mole to supplant the 

 Wandle in the Weald. Thus it is likely that the valley of 



