Glumstenen: The glacial erratic and Halland's ebbing tides

Glumstenen, also known as Glumstenen, is a glacial erratic situated in Glommen, Morups socken in Falkenbergs kommun, Halland. The stone has functioned as a landmark for shipping in former times and has given the location its name. Before the construction of the lighthouse on Morups Tånge, fishermen used Glomstenen for orientation. Today, the stone serves as a windbreak during sea bird watching, as the winds can be quite strong.

In September 1816, Sven Peter Bexell, a well-known Halland historian and church pastor in Grimeton and Rolfstorp, inscribed a message into the stone regarding the mean sea level. Since the beginning of the 1700s, there has been a debate about the so-called water level reduction in the seas. Some believed the land was rising from the sea, while others imagined the seawater was being swallowed by holes in the ocean floor. A third guess suggested a continuous evaporation of the seawater.

Bexell had found old data on water levels in Halland that did not agree with the levels he could observe. He measured the sea level at Glomstenen in September 1816 and had the results carved into the stone for future research. Bexell wrote in his Hallands historia och beskrivning regarding his findings. With modern units, Bexell's median height is 1528 millimeters. He specifies the height on a third line when, which corresponds to a millimeter in our measurements. The transition between the stone and the underlying ground surface may be the reference level Bexell used when measuring the median height of the sea level by a millimeter.

Sources: Wikipedia, OpenStreetMap, Wikidata, Wikimedia Commons