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island connected with the mainland by a roadway carried 

 along the summit of one of the principal dykes. 

 Grouped round the town are the oldest of the valli, for 

 the seaward section of the lagoon, possessing ready 

 access to the sea, was naturally the scene of the initiation 

 and gradual evolution of the complex system now 

 existing. 



To-day the town is 5 kilometres from the seacoast, 

 but I am of opinion from the character of the northern 

 portion of the lido or sea-bar that when Comacchio was 

 founded it was not more than 3 kilometres from the sea.* 

 At that time the valli now existing in the extreme north- 

 east of the lagoon, those between and including Valle 

 Volano and Valle Stefano, probably did not exist, the 

 sea-bar certainly was considerably narrower and access 

 between the lasfoon within and the sea without was much 

 more free that it now is — probably with a well-marked 

 and free tidal flow renewing the water of the lagoon 

 daily, making it a laginia viva or living lagoon such as 

 is paralleled by the condition of that of Venice to-day. 

 Now, the lagoon being dyked all round and with water 

 not in ample and free tidal communication with the sea, 

 it has become the type o{2,lagunamorte or dead lagoon, 

 in the lansruao-e of Italian valli-culturists— an inland sea 

 shut off from the Adriatic, save for the narrow sluices 

 opening from each valle into the marine canals. 



The information we possess concerning Comacchio 

 does not antedate the 6th century, but there can be 

 little doubt that the principles governing the present 

 system of fish-farming were conceived and the foundations 

 of valli-culture laid several centuries earlier. The system 

 followed is in substance similar to that known to and 

 practised by noble Romans shortly before the beginning 

 of the Christian era as detailed by Pliny and other early 

 writers ; it is very probable that its introduction into the 



* This conclusion receives confirmation from the fact stated by Feletti * 

 that the seaward extension of the sea-coast south of the mouth of the Volano 

 has been 20 metres in ten years. If we assign the founding of Comacchio 

 to the 5th century — say 1,500 years ago, this would give an extension of 3,000 

 metres as against the 2,000 which I claim. But of course the rate of deposit 

 is not and cannot be uniform and it is probable that the rate of deposit is 

 rather more rapid now than some centuries ago, as the extension of cultivation 

 and of drainage tends to make floods more violent and so bring down more 

 sediment and so increase the rate of the formation of deltaic lands. (*" Intorno 

 all attuale salsedine della acque del Campo Trebba, " etc., p. 3, Comacchio, 1909.) 



