453 
In tlie formation of our river valleys, m’c must remember that 
the nature of the rocks cut through has exercised some influence 
on their shape according to udiat engineers call the “angle of 
rest.” ^ Wo know in making railway cuttings that the slope is calcu- 
lated in accordance with the nature of the rock, chalk standing in 
wall-hke masses, while clay, or gravel, or sand, have to be cut away 
at angles of from twenty to forty degrees. In our river valleys, as 
before hinted, the Chalk gives a bolder feature, as near Norwich, at 
Attlobridge and liingwood, at Glandford and Letheringsett, and at 
Walsingham and iroughton-in-the-Dale, where it rises more or less 
abruptly to some little height above the river valley, and supports 
masses of Glacial drift above it. 
Gravel forms much steeper slopes than clay, as wo may witness 
on the Blakeney Downs, in the Bure Valley below Briston, and 
other places. Any marked rise in the ground, or change of 
feature, is, as a rule, caused by a change of formation. Such 
features, too, are often indicated on the Ordnance maps by short 
though abrupt turns in a road, which have been made to avoid the 
steep ascent, where one formation rests on another. These features 
are of great aid to the geological surveyor ; for it is by noticing the 
form of the ground, the indications of the soil, of vegetation, and of 
springs, that ho is enabled to draw those boundaries between for- 
mations where no direct evidence is to be found, and where the 
casual observer might attribute the result simply to the imagination. 
Although the land has been sculptured in great accordance with 
the changing strata, our coast-line presents no modifications of any 
particular kind, because, with the exception of the chalk and sand- 
stone cliffs of Hunstanton, we have no hard rocks capable of offering 
p-eat and special resistance to the breakers, and thus to stand out 
in headlands. Ihe coast-line is rapidly receding between Weybourn 
and Eccles, at such a rate (two or three yards a year), that we 
might make calculations to show how much has been lost duriiifr 
the past five or ten thousand years. We cannot say, however, for 
how long a period the conditions have remained as they are, thou"h, 
probably, the unfortunate landlords have suffered from “time 
immemorial.” 
The alluvial flats and salt marshes of Burnham, Wells and 
Blakeney may have been prolonged further east, and bounded on 
the north by hills since denuded ; for Mr. Clement Eeid suggested 
