Sjöbo blocksänkor

Within an area of about 1 km2 there is a form of frost ground, which is usually found in the mountains. The frozen ground in question is known as a block sink and some block sinks are very clear while others are more diffuse. For the block sink to occur, a number of criteria must be met. The terrain consists of many moist depressions, which are surrounded by small hills. The soil is a moraine, which is rich in blocks and rocks. Last but not least, the climate has played a major role in the formation of the block sink.

In short, the block sink has been formed by blocks and rocks being lifted up to the ground surface by frost heaving. During the thaw, the blocks and stones do not fall back into their original position, as fine material has partly filled in the space beneath them before all the frost has gone out of the ground. The boulders and stones are piled up more and more year after year. During the annual development process, there has also been a simultaneous movement of boulders and rocks from the moraine slopes down towards the depression.

From originally being a damp or water-filled depression with a few boulders and stones at the bottom, it can be assumed that the boulder depression was formed during a relatively short and vegetation-free period immediately after the melting of the ice sheet from the area about 13 000 years ago.