58 THE SILTING UP OF THE DEE: ITS CAUSE. 
THE CAUSE OF THE BORE. 
The slope of the tidal flow between Hilbre and Chester.— 
I have already stated that it is nearly high water at Hilbre 
when the bore or head of the tide passes the Cheese-stage at 
Chester. Now, the channel between Hilbre and Chester is 
about 25 miles in length, and if we suppose a tide to rise 25 feet 
at Hilbre, it follows that when the head comes up to Chester 
the slope would be z5 feet in the 25 miles, or one foot per mile. 
This body of water, travelling at an average rate of five miles 
an hour, is invited to enter our river at Connah’s Quay by an 
opening 850 feet wide, which is shortly reduced to 500 feet, 
and thence to Chester, narrowed in seven miles to 280 feet. 
Oan we wonder that the destructive bore is the consequence ? 
It must be understood that all my observations refer to ordinary 
or high spring tides; of the neap tides the phenomena are the 
same but much less in degree. 
THE EFFECTS OF THE FRESHES. 
The fresh water floods or ‘“‘freshes” clear the channel 
between Chester and Flint.—In an average year there are some 
half-dozen freshes, which clear out of the bed of the river much 
of the sediment brought up by the tides. Were it not for such 
floods the Dee, from Chester to Connah’s Quay, would have 
been reduced to a brook long ago, but on the whole I am 
informed by the supervisor of the river that the upper part, say 
from the Higher Ferry to the causeway, is being silted up 
despite the partial effects of occasional floods cutting out 
a channel. This is the strongest evidence that the silting up 
is from the seaward, because the river is very free from 
sediment above the causeway except during floods, and these 
appear to be so strong at times as to be able to carry their own 
sediment into the estuary, together with much of the sediment 
deposited by the tide between the occurrence of each fresh. 
The force of these freshes is exhausted in attempting to undo 
in as many days what the tides have been doing in as many 
weeks. Now suppose we got rid of the bad effects of the in- 
coming tide, and strengthen the power of the freshes or floods 
coming down from Bala to the sea, by so reconstructing our 
river between Chester and Flint, as to make it as difficult for 
sediment to come up, and as easy as possible for the freshes to 
remove any that might so find its way in; or in other words, 
endeavour to utilize the force of the freshes to the uttermost, 
whilst reducing to a minimum the power of silting up the 
channel by the incoming spring tides, then we might, I think, 
undo much of the evil of the past, and many of us live to see 
Chester once more recognised as an important port of Her 
Majesty’s United Kingdom, and again justify the words of the 
writer in the 14th century, who described our town as situated 
