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 valley, 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. 
