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Read Ebook: Geflügelte Worte: Der Citatenschatz des deutschen Volkes by B Chmann Georg Robert Tornow Walter
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It is not easy to realise what the conditions were during the formation of the later Terrace Gravels , and, if it is a fact, why there was not then, as in later times, a marshy peat-bearing area here and there between the torrential deposits of the upper streams near the foot of the hills and the region where the tide met the upland waters. A few plants have been found in the Barnwell gravel but they are very rare in this series. The older Terrace Gravel might be expected to furnish evidence of the existence of abundant vegetation if we are right in assigning it to about the age of the peaty deposits overlying the Weybourn Crag. But at present we have no evidence of any such deposit in the Cambridge gravels.
Although there are great masses of vegetable matter formed in the swamps of tropical regions, peat is essentially a product of northern climes. Pliny evidently refers to peat as used in Friesland but not as a thing with which he was familiar.
FEN BEDS NOT ALL PEAT.
It must not, however, be imagined that the Fen Beds consist wholly or even chiefly of peat. As we travel north from Cambridge the surface of the alluvium is brown earth for miles and only here and there shows the black surface of peat. The numerous ditches for draining the land confirm this observation, and when we have the opportunity of examining excavations carried down to great depths into the alluvium we usually find only a little peat on the surface or in thin beds alternating with silt and clay and marl. Sometimes, but only sometimes, we have evidence of the growth of peat for a long time, then of the incoming of turbid water leaving beds of clay, then again of the tranquil growth of peat. All this points to changes of local conditions and shifting channels during a gradual sinking of the area, for some of the peat is below sea level.
I believe that the volume of clay is much greater than that of peat, although from the common occurrence of peat on the surface and clay in the depth the area over which peat is seen is greater. We have not, however, the data for estimating the proportion of each.
In embayed corners along the river even above Cambridge we find little patches of peat, while on the other hand in deep excavations near the middle of the valley we find only thin streaks of peat or peaty silt. In the trial boreholes at the Backs of the Colleges there was only this kind of record of former swamp vegetation.
SECTIONS IN ALLUVIUM.
In digging the foundations for the chimney of the Electric Lighting Works opposite Magdalene College the following section was seen .
Under the new Tennis Courts in Park Parade facing Mid-summer Common the section was somewhat different .
While in the pit dug some years ago by Mr Bullock at the other end of the Parade at the lower end of Portugal Place in the south-east corner of the Common there was a section very similar to the last .
These three sections, immediately north of Cambridge where the valley of the Cam opens out on to the Fens, are important as showing the variations right across the alluvium from side to side and the absence, here at any rate, of any indication of a constant sequence distinctly pointing to important geographical changes. A section seen under Pembroke College Boat House gave 16 feet of clay and peaty silt on the black gravel which here, as in the borings at the Backs of the Colleges, forms the base of the alluvium. About half way down were bones of horse and stag, but I do not believe that these are of any great antiquity, probably not earlier than mediaeval.
Thickness Depth
Lower down the river near Ely a most important and interesting section has recently been exposed. A new bridge was built over the Ouse near the railway station and to obtain material for easing the gradient up to the bridge a pit was sunk close to it on the east side of the river, and was carried down to the Kimmeridge Clay thus giving a clear section through the whole of the alluvium .
Depth
If now we travel about 30 miles a little west of north we shall arrive near the shore of the Wash about half way across its southern coast line at Sutton Bridge. Here I had an opportunity of seeing the material of which the alluvium is composed. With a view to securing a sound base for the foundation of the piers of the Midland and Great Northern Railway bridge an excavation was made through the whole of the Fen Beds down to the Boulder Clay which as I have already stated was reached at a depth of 73 feet. The clerk of the works kindly gave me the following measurements .
Depth Thickness
Here again we see that the only peat is a bed between three and four feet in thickness of mixed loam and peat more than 40 feet below mean sea level.
From these sections it is clear that along the direct and more permanent outfall from Cambridge to the north, peat forms but a small part of the Fen Beds.
Peat is a substance of so much value as fuel, of such importance to the agriculturist, of such commercial value in what we may call its by-products, and of such scientific interest in the history of its formation and the remains which its antiseptic properties have preserved, that it has, as might be expected, a large literature of its own.
I have before me a list of more than 150 references to peat or to the Fens.
PEAT; TREES AND OTHER PLANTS; TARN PEAT AND HILL PEAT; BOG-OAK AND BOG-IRON.
It is worth noting when trying to read the story of the Fens as recorded by their fallen trees that in all forests we find now and then a few trees blown down together though the surrounding trees are left. This may be the result of a fierce eddy in the cycloidal path of the storm, but more commonly it seems to be due to the fact that every tree has its "play," like a fishing rod, and recurring gusts, not coinciding with its rhythm, sometimes catch it at a disadvantage and break or blow it down.
The story told by the West Fen trees is quite different from that told by the water-borne and water-worn trunks in the section by Ely station.
The same variable conditions prevailed also in the more westerly tracts of the Fen Basin, but the above examples are sufficient for our present purpose.
When Ingulph says that portions of the Fenland were disafforested by Henry I, Stephen, Henry II, and Richard, who gave permission to build upon the marshes, this probably meant that they no longer preserved them so strictly, but allowed people to build on the gravel banks and islands in them.
Dugdale, recording a stricter enforcement of game-laws, quotes proceedings against certain persons in Whittlesea, Thorney and Ramsey for having "wasted all the fen of Kynges-delfe of the alders, hassacks and rushes so that the King's deer could not harbour there." He does not mention forest trees.
In the growth and accidents of vegetation in a swamp there are som
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