FLORA OP CENTRAL NORFOLK. 391 



valleys were raised, by alternate beds of moor and silt, to 

 the high-water mark of the fresh streams that continue to 

 drain through them. There are now three rivers meandering 

 through the central tract of the estuaries that have preceded 

 them^ the lateral formations of moor and silt having been 

 converted into valuable marsh and pasture lands ; that to 

 the northward of the three is the Bure ; it is the most 

 irregular in its course, and is connected with several shallow 

 lakes that have been left where the silting process has been 

 checked, or the draining less perfect. The second river is 

 the Yare, which is rendered somewhat important by being 

 navigable between Norwich and the sea-port of Yarmouth. 

 The third river is the Waveney, which forms the natural 

 boundary of the contiguous counties of Norfolk and Suffolk. 

 At the confluence of these rivers a lake is formed, which 

 reaches to within half a mile of the sea, then contracts again 

 into a narrow stream, turns sharply to the south, and con- 

 tinues its course for three miles in that dii'ection, separated 

 from the ocean by a low tongue of sand only, which is over- 

 flown by the highest tides, and then suddenly empties itself 

 into the German Ocean, where the cliffs of Suffolk com- 

 mence to raise themselves above the flats of Norfolk. 



The botanical stations of the county all bear a direct rela- 

 tion to the geological features which have been thus suc- 

 cinctly sketched. 



In the immediate vicinity of Yarmouth the coast is a flat 

 plain, but more to the north the sand has accumulated under 

 the action of the wind and tide, and formed a line of sand- 

 banks which offer a natural barrier to the encroachments of 

 the ocean. In several positions these banks rise to a con- 

 siderable height, and the labours of the plough may be seen 

 to extend to within a quarter of a mile of the sea ; the safety 

 to the agricultural district, from its close neighbourhood to 

 these loose and mobile sands, being provided for by a series 

 of grasses and sedges, (the most characteristic of which are 

 the Carex arenaria and the Triticum junceum,) which inter- 

 lace their creeping roots, often extending to the distance of 

 many yards, and thus bind into a firm soil that which would 

 otherwise render useless to the cultivator the inland country 

 for miles. 



Somewhat more removed from the coast than these regions 

 of sand, on the immediate banks of the lower parts of the 

 rivers, and around the broader waters, is an extent of marsh 

 ground entirely distinct from all other regions in its vegetable 

 productions, in consequence of its being periodically over- 

 flown by salt water. These are known as the Salt Marshes, 



