They are merely craters raised above the level of the surrounding country by the gradual accretion of the soft oily mud, which overflows at frequent intervals whenever a discharge of gas occurs.
The opening of railway communication with London in 1906 resulted in a considerable accretion of residential population.
Its seaward accretion is estimated at 6 ft.
It is unique, however, among the great promontories of the south coast of England, the accretion of gravel banks falling into deep water contrasting with the cliff-bound headlands of the North Foreland, Beachy Head and the Lizard, and with the low eroded Selsey Bill, off which the sea is shallow.
There is a gunnery establishment in the harbour on Whale Island, the area of which has been increased to nearly 90 acres by the accretion of material excavated from the dockyard extension works, and various barracks including those of the royal marine artillery at Eastney, beyond Southsea.
It will be seen that the only European country which gains by the exchange is France, and there the accretion is almost insignificant.
It was the final stage in a process of accretion dating back to the beginnings of the Christian reconquest in the 8th century.
Herbart apperception is that process by which an aggregate or "mass" of presentations becomes systematized (apperceptionssystem) by the accretion of new elements, either sense-given or product of the inner workings of the mind.
In view of the many evidences of the linguistic character of Sumerian as opposed to the one fact that the language had engrafted upon it a great number of evident Semitisms, the opinion of the present writer is that the Sumerian, as we have it, is fundamentally an agglutinative, almost polysynthetic, language, upon which a more or less deliberately constructed pot-pourri of Semitic inventions was superimposed in the course of many centuries of accretion under Semitic influences.
Three more distinguished names likewise passed away in 1853, though without any attendant accretion to British territory.