2 66 



HARDWICKE'S SCIENCE-GOSSIP. 



(often containing sea-shells) show that from time 

 to time the forests were inundated and destroyed by 

 the waters of the sea, and were buried beneath the 

 muddy deposits which resulted from the inundation. 



Even in historical times, the sea has often broken 

 through the sandhills and has flooded large tracts of 

 the marsh behind them, and the result of such inun- 

 dations has always been to raise the surface of the 

 land, by warping it up with the silt deposited from 

 the muddy waters as they gradually evaporated. 



The stiff brown clay which immediately underlies 

 the soil near Mablethorpe, and in most other parts 

 of the Wash, is probably the latest warp or sediment 

 deposited in this manner, and some of it has doubtless 

 been formed since the earliest banks and drains were 

 made. 



Thus was gradually built up the thick mass of clays, 

 generally between thirty and fifty feet thick, which 

 lies below the Lincolnshire marshland. Many cen- 

 turies must have been occupied in its formation ; but 

 the climate does not seem to have differed much from 

 that which we now enjoy, the shells are of the same 

 species as those which now live on the Mablethorpe 

 shore, and the trees are chiefly oak, birch and willow, 

 like those which now exist on clay soils. It is possible, 

 however, that the greater height of the land and the 

 wider extent of forest growth, caused the rainfall to 

 be greater than it is at the present time. Modern 

 geology admits no great cataclysms or convulsions of 

 nature, except where volcanic action has come into 

 play, and of that there is no trace in Lincolnshire ; 

 All the changes above described have been produced 

 by a gradual change of climate, accompanied by 

 slow and comparatively slight movements of the land, 

 and by the constant operation of waves, tides and 

 currents. 



The only other physical feature which remains to 

 be accounted for is the long line of sand-hills which 

 form a border to the marshes and protect them from 

 the inroads of the sea. The mode in which these and 

 similar dunes have been slowly built up to their 

 present height, has often been described — the growth 

 of grass and reeds along the margin of the shore, the 

 arrest of the drifting sand and its accumulation round 

 the patches of vegetation, shifting, yet ever rising 

 higher and becoming firmer with the matted growth 

 of reeds and other plants, till by degrees a barrier of 

 steep sand-hills is raised by the action of wind and 

 waves. 



It is possible that the origin of these dates back to 

 the time when the area first began to silt up, and that 

 the marsh land has never been without a protecting 

 fringe of sand dunes. It is certain that they have 

 shifted their positions from time to time according as 

 storms and changing currents have caused the loss or 

 gain of land at different points ; of one such alteration 

 we have evidence in the low ridge called Croft Bank, 

 along which the Roman road is carried from Wain- 

 fleet to Skegness ; this appears to have been a sandy 



beach at one time, and was probably backed by a line 

 of sandhills, but the shore in front gradually silted 

 up and formed the marsh which now intervenes 

 between Croft Bank and the present sea margin, 

 while a new line of sand hills began to be formed 

 along its edge. 



There is one other feature of interest connected 

 with this part of the Lincolnshire coast, and that is 

 the ancient forest bed which is exposed for some dis- 

 tance along the shore at low water. Mr. T. W. Wallis 

 has recently given some account of this, as seen at 

 Mablethorpe on the occasion of an unusually low 

 tide (Sept. 28,1878) ;* the following may be quoted 

 from his description : — 



' ' At this low water the old partly-submerged forest 

 was well exposed, as far as the eye could reach, right 

 and left, and many miles beyond. The width of the 

 old forest exposed was great, but a succession of 

 points of tree stumps kept appearing, far into the sea, 

 so as to prove we saw only a portion of the old forest. 

 Some of these tree stumps at Mablethorpe are very 

 large, with large root arms branching out, but the 

 major part were small trees ; they are very numerous 

 and stand from one to three feet above the clay, they 

 are firm and sound, generally the upper end of each 

 stump tapers to a point, caused by the long continued 

 friction of the sea. I selected the most handsome 

 stump, one literally encrusted with small shell fish, 

 it stands about twenty inches high, and has been 

 about ten inches in diameter, though perhaps only 

 about a quarter of its original bulk remains. I had 

 about one half of it cut off by a cross-cut ; the wood 

 is fir, and by counting the layers of growth I make it 

 out to have been one hundred years old." 



The origin and date of this ancient forest bed has 

 not yet been fully investigated ; it may be the 

 termination of one of those which occur underground 

 in the marsh behind, or it may be a more recent 

 growth upon ground which has subsequently sunk 

 beneath the sea. I am strongly inclined however to 

 think that the former will prove to be the correct 

 view of the case. 



We have now reached the end of the geological 

 record ; how long the land remained in an unre- 

 claimed state we have no means of knowing, but 

 the early British found food and shelter among its 

 woods and marshes, and are believed to have con- 

 structed certain banks and drains, but these are 

 matters which come rather within the province of 

 archeology and we leave the antiquary and the 

 historian to take up the pen which the geologist 

 here lays down. 



Localities for Fossil Star-fish.— I am glad to 

 inform Dr. Charles Ricketts, that I also obtained a 

 specimen of Protaster Salteri, near Llangower, about 

 two years ago ; both sides perfect." — Owen Rees. 



* In the Louth Times for May 3, 1873. 



