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see that it occasionally gave battle to the fresh- waters and 
their prey at this period by the existence of channels filled 
with marine silt running up into the blue clay in the form 
of bays and creeks. This stratum contained amply sufficient 
fertilizing matter for the sustenance of the finest trees of 
various kinds, and from it sprang up oaks of vast dimensions, 
lofty firs, alders, birch, and hazels, whose roots are still 
firmly fixed in the soil that originally so amply nourished 
them, whilst their innumerable trunks lie prostrate beneath 
a funeral pall of black peaty earth created by the debris of 
their own leaves mixed with decayed vegetable matter, such 
as stagnant waters always produce. 
Occasionally, but more rarely, the sea still disturbed 
these vegetable cemeteries, for we find silty deposits in some 
portions of the fens of considerable thickness above the 
peaty stratum, and in a few instances alternating with it 
more than once.* How long the lands we are speaking 
of remained at a sufficiently high level above both fresh and 
sea waters to enable them to nourish trees of great size, 
including oaks varying from one foot to ten in diameter, is 
of course, uncertain, but from the last-named dimensions we 
may safely presume that this period of their growth lasted 
for five centuries. Again, how long these fen districts 
continued to be covered with stagnant fresh-water, after 
they had wrought such terrible ruin upon thousands of 
acres of the finest forest lands, is undeducible from any 
internal evidence, but they certainly were for the most part 
still prevalent, when a new and intelligent power drew near, 
already well practised in the art of combating with nature 
as well as with man, and that was the power of Rome. 
Probably the Romans were attracted to take possession of 
* In Sutton, St. Edmund's Parish, two strata of peat are found, alternating 
with others of silty clay, two or three feet thick ; also in Ramsey Fen, where, 
below the peaty surface and a clay substratum, a second deep deposit of peat 
exists. 
