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Lövgrund watermark
Lövgrund watermark
In the mid 1700's, Celsius, a well known Swedish scientist for its temperature scale, was asked to measure the rate of decrease of the water in the Baltic sea. He studied it in a couple of islands and Lövgrund is one of them, located a few miles north of Gävle in the Bottenhavet.
The Celsius stone, from Lövgrund gästhamn.
The decrease of the water sea level in the Baltic sea has been an issue for century in Sweden with villages having to move location to remain along the sea shore. Celsius decided to look at rocks that had been documented to host seals, and therefore have a value for seal hunters. Seals love to get on rocks to bask under the sun, but given their mass, they can only access rocks that are flat and very close to the water level. Going along the shore of Sweden, he documented such seal rocks and questioned the local population about how long these rocks were used by seals. By analysing these data, he could figure out a rough rate of decrease, which he estimated to be 1.4 cm per year. This was a bit overestimated as the rate of decrease is between 0.8 cm and 1 cm along the sea of Bothnia.
If you enlarge the picture on the left, you can sea where the water level was in 1731, 1.65 meters higher than today, and where it was in 1831 and 1931. The stone is getting on the shore nowadays, and there has been at least two centuries that the seals have deserted it.
Ratan water mark
Ratan water mark
In Ratan also memories remain from the 1700s interest in Wattuminskningen in our oceans. To measure the apparent "reduction" - which of course, in fact, was due to land uplift - stabbed to the water level marks on the steep shore rocks. In the 1890s, built a mareograph that could better record water levels.
http://www.sevart.se/sv/umearegionen/kulturum-ratan.html
https://www.google.com/maps/search/?api=1&query=%2063.990366,%2020.894043
Landsort water marks
Landsort water marks
In Landsort on Öja, you can find water marks in the österhamn, as well as a mareaograph (yellow small building) to measure the level of the sea, as established throughout Sweden after the study by Celsius.
Anders Celsius
Anders Celsius
Links
- Martin Ekman, The Changing Level of the Baltic Sea during 300 Years: A Clue to Understanding the Earth
- Martin Ekman, An Investigation of Celsius’ Pioneering Determination of the Fennoscandian Land Uplift Rate, and of his Mean Sea Level Mark
- Rosentau, A., Harff, J., Oja, T., Meyer, M., 2012. Postglacial rebound and relative sea level changes in the Baltic Sea since the Litorina transgression. Baltica, 25 (2), 113-120. Vilnius. ISSN 0067-3064
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