Introductory 77 



Finally, to the south of this the chalk lands rise gradually 

 as plateaux or hills of moderate height, characterized by plan- 

 tations of beech and fir, and by the usual vegetation of dry 

 down-lands. In addition to these main divisions the parish 

 of Gamlingay on the extreme west, and the Isle of Ely proper, 

 are chiefly of the Lower Greensand formation ; at Chippenham 

 an expanse of loose sand and gravel overlying the chalk leads 

 to the similar country towards Brandon and Thetford in 

 Norfolk, while at the extreme north of the county, above 

 and below the town of Wisbech, is a dried-up marsh, formed 

 by the silt of the river Nene. Isolated eminences or ridges of 

 Boulder-clay or gravel are also scattered over the Fen districts. 



No account is here taken of the state of the country before 

 the period of the Roman occupation and for some time subse- 

 quently, when it is supposed to have been kept fairly dry by 

 natural drainage, and was covered in many places by woods, 

 orchards, or vineyards ; for even then it is evident from the 

 bones discovered in the Fens that a certain amount of marsh 

 land must have existed. 



No large sheets of water are now to be found in the 

 county 1 , and even Whittlesey Mere, just within the Hunting- 

 donshire boundary, was drained in 1851, while, as might be 

 expected from the fact that the town of Cambridge is little 

 more than from twelve to fifteen feet above the average tide 

 level in Lynn Deeps, the rivers run sluggishly between their 

 muddy banks. 



The Avifauna of the different areas naturally depends to a 

 great extent upon their physical characters : in the Fens, for 

 instance, the Sedge, Reed and Grasshopper Warblers, the 

 Reed Bunting and the Snipe, with an occasional Montagu's 

 Harrier or Short-eared Owl, as above-mentioned, are the most 

 characteristic species ; in the gravel and clay district the 



1 Soham Mere must once have been of considerable dimensions, 

 as is shown by ancient maps, while Stretham Mere was a similar but 

 smaller piece of water. The former was drained by 1793 and the latter 

 even earlier. 



