FLEVO LACUS
FLEVO LACUS and FLEVUM OSTIUM. Drusus, the son of Livia, and the brother of Tiberius, when he held a command on the Rhine, employed his men in making a canal to join the
Rhine and the
Yssel. This canal, called the Fossa Drusiana or Fossae Drusinae, commences below the separation of the
Rhine and
Waal, and joins the
Yssel near
Doesburg. (
Tac. Ann. 2.8;
Suet. Cl. 1.) Germanicus, the son of Drusus, passed with his ships from the
Rhine, through this canal, into the lakes and the ocean, and as far as the mouth of the Amisia (
Ems).
The water of the
Rhine being thus partly diverted into the
Yssel made a new outlet for that river, which outlet Pliny (
4.15) calls Flevum.
He says “that Helium and Flevum are the names of the two mouths into which the Rhine is divided, on the north flowing into lakes, on the west into the river Mosa; it preserves by an outlet intermediate between the two a moderate channel for its own name.” The Helium Ostium is the outlet of the
Maas, which now receives the Vahalis (
Waal).
The outlet of the Flevum Ostium was into a lake, which Mela (3.2) thus describes: “The Rhine not far from the sea is distributed in various directions, but to the left the Rhenus is a river even then and until it enters the sea; on the right it is at first narrow and like unto itself, afterwards the banks recede from one another far and wide; and now, no longer a river but a large lake, it is called Flevo where it has filled the plains; and surrounding an island of the same name it becomes again more contracted, and flows out again in the form of a river.” Mela here mentions only two mouths, but Ptolemy (
4.9), besides the outlet which he calls the Mosa [
MOSA], enumerates a western outlet of the Rhine, a middle outlet, and an eastern outlet; the last ought to correspond to the Flevum.
The lake which Mela describes corresponds to the
Zuider Zee. Ukert (
Gallien, p. 151) observes that Mela does not say that the Flevum enters the sea; and he translates the last words, “iterumque fluvius emittitur,” “and comes as a river out of the lake.” He admits, however, that Mela assumed that the Flevum entered the sea; and nobody can doubt that, when Mela says it flows out again in the form of a river, he means to say that it enters the sea in a form like the other branch, though its course had been made different by passing through a great lake. Geographers have attempted to determine Mela's island, which is a useless attempt, for the lake has undergone great changes since Mela's time; and, besides that, his description may not be exact.
It is certain that there were large lakes, or a large lake, near the outlets of the
Rhine; for, besides the passage of Tacitus already mentioned, he says that Germanicus, on a previous occasion (
Ann. 1.60), after sending Caecina through the country of the Bructeri to the Amisia, and appointing Pedo, who had the charge of the Frisian country, to command the cavalry, embarked four legions and took them through the lakes. Infantry, cavalry, and fleet all met at the Amisia.
These lakes then were navigable in the Roman period; and it is an erroneous, though common statement, that the
Zuider Zee did not exist then.
The enlargement that the
Zuider Zee has received by the encroachment of the sea has probably been chiefly on the west side, where the coast is flat and the water is shallow. Along the east side there is deeper water. In 1219 the sea is said to have broken in and to have carried away the dikes; and another invasion, in 1282, which did great damage, is also recorded.
It seems probable that the outlet of the
Zuider Zee is the part that has been chiefly enlarged, the part that lies north of the channel between
Stavoren and
Medenblik, for it is said that old
Stavoren was swallowed up by the sea.
It is conjectured by Walckenaer that the Nabalia of Tacitus (
Tac. Hist. 5.26) is the
Yssel, and that the Fossa of Drusus, from
Arnheim to the
Yssel at
Doesburg, formed, with the course of the
Yssel into the lake or lakes, the north-eastern limit of Gaul.
He further conjectures that the name Flevum was given to the stream which flowed out of the lake into the North sea. Accordingly, he supposes that the Castellum Flevum (
Tac. Ann. 4.72) may have been at the outlet of the Flevum, which channel completed the north-eastern limit of Gallia.
He further supposes that the island of
Vlieland, one of the four which lie in front of the
Zuider Zee, and form a barrier against the ocean, may represent the Flevum Castellum. (Walckenaer,
Géog. des Gaules, vol. ii. p. 294.)
Thus the
Vlie-Stroom, between the islands. of
Vlieland and
Schelling, may represent the old mouth of the Flevum, as it subsisted before the great flood of the 13th century enlarged the lake Flevo, detached the islands of
Schelling and
Ameland from the main, and buried in its waters the numerous villages of the district of
Stavoren. (Walckenaer, vol. ii. p. 201.)
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G.L]
