300 EOCENE PERIOD. [Ch. XXI. 



the line, whereby the effect of a double axis of elevation was 

 in some measure produced. 



In order to give a clearer idea of the manner in which the 

 chalk-hills are intersected by these transverse valleys, we subjoin 

 a sketch (No. 73) of the gorge of the river Adur, taken from the 

 summit of the chalk-downs, at a point in the bridle-way leading 

 from the towns of Bramber and Steyning to Shoreham. If the 

 reader will refer again to the view given in a former wood-cut 

 (No. 65, p. 290), he will there see the exact point where the 

 gorge, of which we are now speaking, interrupts the chalk 

 escarpment. A projecting hill, at the point a, hides the town 

 of Steyning, near which the valley commences where the Adur 

 passes directly to the sea at Old Shoreham. The river flows 

 through a nearly level plain, as do most of the others which 

 intersect the hills of Surrey, Kent, and Sussex ; and it is evi- 

 dent that these openings, so far at least as they are due to 

 aqueous erosion, have not been produced by the rivers, many 

 of which, like the Ouse near Lewes, have filled up arms of the 

 sea, instead of deepening the hollows which they traverse. 



In regard to the origin of the transverse ravines, there can 

 be no doubt that they are connected with lines of fracture, and 

 perhaps, in some places, there may be an anticlinal dip on both 

 sides of the yalley, as suggested by a local observer *. But 

 this notion requires confirmation. 



No. 74. 



Supposed section of Transverse Valley. 



The ravine, called the Coomb, near Lewes, affords a beautiful 

 example of the manner in which narrow openings in the chalk 

 may have been connected with shifts and dislocations in the 

 strata. This coomb is seen on the eastern side of the valley 

 of the Ouse, in the suburbs of the town of Lewes. The steep 

 * Martin, Geol. of Western Sussex, p. 64, plate III. fig. 3. 



