Essay on the Theory of the Earth - baron Georges Cuvier

ON THE LEVEL OF THE BALTIC.

About the middle of the last century, a controversy took place among the natural philosophers of the north of Europe, regarding the alleged gradual lowering of the level of the sea in general, and of the Baltic Sea in particular. Celsius was the first who introduced this idea to notice. He generalised it by applying it to all the planets, and was supported by the authority of the celebrated Linnæus. He soon perceived, however, that the point could never be settled by mere discussion, and that facts alone could lead to any certain result. Observation was therefore had recourse to; and thus the dispute in question had at least one good effect, that of directing to the subject the attention of men of science, whose situation might enable them to mark the variations of level that take place along the coasts of the North Sea. The results of investigations undertaken for this purpose, are now beginning to be collected.

In the course of 1820 and 1821, Mr Bruncrona, assisted by the officers of the Pilotage Establishment, and other qualified persons, undertook the examination of all the authentic measures that had been established upon the west coast of the Baltic, during the last half century. The results of this examination are given in a short memoir, inserted in the Swedish Transactions for 1823. The following table indicates the degree to which the level of the sea has fallen during the last forty years, on the coast of Sweden, at various latitudes. It is proper to remark, that, in some of the places observed, the measures were much older, and in some others much more recent, than the period of forty years. In both these cases, the change of level that must have been effected during this period, has been estimated, by calculating the mean annual depression furnished by the observations.


Latitude.		Fall of surface in forty years.	Latitude.		Fall of surface in forty years.	Latitude.		Fall of surface in forty years.

East Coast.		Feet.	East Coast.		Feet.	East Coast.		Feet.
63°	59′	1.50	59°	17′	2.17	56°	10′	0.00
...	...	2.50	58	44	1.00	56	11	0.00
...	...	0.50	58	42	1.08	55	53	0.00
61	43	2.50	58	45	1.17
61	37	2.83	58	35	2.00	South-West Coast.
61	32	2.50	58	28	0.07	55	23	0.00
61	45	2.50	58	11	0.83	55	22	0.00
60	11	2.33	58	8	1.00	57	21	0.00
59	46	0.17	57	50	1.00	57	53	1.00
59	46	2.00	56	41	0.41

Of the facts collected in the course of this investigation, the following may be mentioned as tending to support the opinion of a fall of level.

1st, It is generally believed among the pilots of the Baltic, that the sea has become shallower along the course which vessels ordinarily follow; but, it is added, that this alteration is more sensible in the places where the tide collects sand, detached pebbles, and sea-weeds, or in those where the bottom is composed of rocks. The same observation has been made in the neighbourhood of some large towns and fisheries; for example, a hydrographic chart made in 1771, gives six fathoms for the mean depth of the sea opposite the harbour of Landskrona, whereas, in 1817, the sounding line scarcely gave five fathoms at the same point.

2d, According to the oldest and most experienced pilots, the straits which separate the numerous islets scattered along the coast of Sweden, from Haarparanda to the frontiers of Norway, received vessels that drew ten feet of water; now they are not practicable for boats that draw more than two or three feet.

3d, The pilots further affirm, that, along the whole coast of Bahusia, the bottom undergoes a diminution, which becomes sensible every ten years in certain places, where it is composed of rocks. Several other parts of the Baltic may be cited, in which a similar change has been remarked.

M. C. P. Hallstrom, in an Appendix to Mr Bruncrona’s Memoir, gives the following table of the diminution observed in the depth of the waters of the Gulf of Bothnia.