The absence of rocks and seaweeds forbids the abundance of certain fishes and Mollusca, so that the ornithologist may in some measure infer as to what particular species of birds would from choice be usually scarce or abundant. Surface-feeders are well represented, but those which dive or prey upon Mollusca, and those that delight in rocky and precipitous habitats, are generally uncommon, or merely storm-driven stragglers. An exception exists in the Scoter, numbers of which frequent the Broads all the winter, feeding upon the smaller bivalves which are apparently in spots plentiful at the bottom (vide note on Scoter).
The northern sand-hills mostly slope gradually into marshy levels or cultivated fields, reaching their level in the Broad-lands and the valley of the Bure.
Southwards of the town, after passing the mouth of the Yare, stretching away towards Lowestoft, is a range of crumbling sand-cliffs, the fields above which are cultivated to the very edge. A straggling colony of Sand-Martins nests here. All westward of the cliffs is cultivated, and merges off into a fairly well-wooded district, notably at Fritton and Belton, excepting which scarcely anything worthy of that name exists within the limits comprised in the district to which these remarks refer. Small thickets occur at the margins of some of the Broads, and a few carrs of alder and willow, interspersed with birch, are irregularly scattered over the swampy parts of the marshes, but seldom covering more than an acre or two of ground.
To the west of the town is the great alluvial flat, once the bed of the great estuary known to the Romans as Garienis ostium, and up which their galleys passed to their camp at Caistor, beyond Norwich. Remains of this estuary and the branches now exist in the famous Norfolk Broads, most noticeable of which is Breydon Water, into which the Yare, the Waveney, and the Bure empty their sluggish streams.
Before Breydon was walled[1] and the rivers banked, and the
- ↑ Breydon, five miles long and one in width, is surrounded by a winding mound or dyke, faced with jagged flints and backed with grass, forming a triangular barrier. The rivers are similarly confined. The ditches formed by the soil removed drain the marshes, and are connected with a network of others. Steam drainage mills pour the surplus water over into the rivers. Hence, although the marshes grow drier year by year, they are always below the level of high water.
