Haga Tingshus Jättegryta


Useful Information

Location: 12 Annerovägen, Stockholm, 169 70.
(59.3535, 18.0398)
Open: no restrictions.
[2021]
Fee: free.
[2021]
Classification: ExplainGlacial Mill
Light: n/a
Dimension: Ø=1 m, VR=2.7 m.
Guided tours: self guided
Photography: allowed
Accessibility: no
Bibliography:  
Address: Haga Tingshus Jättegryta, 12 Annerovägen, Stockholm, 169 70, Tel: +46-.
As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
Please check rates and details directly with the companies in question if you need more recent info.

History

1905–07 courthouse built and glacier mill discovered.
1996 courthouse facade and metal roof renovated.
2000 basement spaces rnovated.

Description

Haga Tingshus Jättegryta (Haga Courthouse Giant's Kettle) is geotope, which is located in the basement of a court house, the Haga Tingshus. It is normally not possible to enter the basement, but there is a weird window which allows a look at the dolly tub. You get a glimps into a basement room with a hole in the middle. It was discovered when the construction of the courthouse had been started and was incorporated into the basement. The spherical rocks which were found on the bottom of the kettle, the drillstones, were reused. Two of them were placed on top of the courthouse gateposts, which were later moved to the back of the house.

This is an impressive geotope though it is actually not underground, so we want to explain first, why it is listed on showcaves.com. The first reason is, that even vertical shafts are considered caves if they are big enough to be entered by man. The bigger ones are generally called daylight shaft or pothole. On the other side, this is a sort of very short gorge, and we also list gorges.

So it is obviously time to explain what this hole is. When the rock surface is covered by a glacier, the ice is often melting on the surface of the glacier, during summer for example. The melting water flows on the surface, reaches a shaft and enters a glacier cave. Typically, the water melts a shaft into the ice down to the bedrock, where it starts to flow on the surface downhill through a glacier cave. This kind of mill is formed at the point where the water reaches the bedrock after falling down the shaft. It has a lot of energy and starts to form a hole, later rocks are moved around the hole, and it works like a drilling machine. The result is a hole with rounded forms, which is actually the same as any dolly tub in a river bed or gorge. And if the shaft moves, for example by the moving glacier, series of such holes are drilled.