Giant's kettles - potholes shaped by meltwater

Discover Sörmland
Discover & Learn
Go to content

Giant's kettles - potholes shaped by meltwater

Discover Sörmland Blog
Published by Stefanie Schlosser in Ice Age · 13 January 2022
Tags: iceagepotholegiantskettle
As introduction to the last ice age, please check out this blog post.
By the end of the last glacial period, around 10 000 years ago, huge bodies of ice began to melt and created massive meltwater-streams. The water not only ran off on top of the remaining glaciers but as well penetrated in cracks and holes, creating flows of water in and under the body of ice.
The underlaying bedrock had already been freed from any biological layers, like soil and vegetation, through the movement of the ice under the glacial period that was just coming to an end. The blank rock was therefore directly exposed to the streams of meltwater.

Through naturally occurring fluctuations and the transport of varying amounts of debris, certain places turned into a trap for cobbles or boulders of different sizes. Instead of continuing their way with the flowing stream of water, they would simply rotate round and round on the same spot and thereby create a deeper and deeper cavity, which in itself could accumulate more debris. This self-enhancing process went on over some thousands of years, depending on the location and the availability of meltwater.

Fig 1: Creation of a giant's kettle by meltwater - illustration (Jasmin Ros; CC0 1.0)

Let’s talk about the various names and the myths behind. Synonyms for giant’s kettle are giant’s cauldron, glacial pothole or moulin pothole, with “moulin” referring to the French word for mill. The Swedish term “jättegryta” means directly translated “giant’s pot” and derives from the folk belief that giants and trolls used to prepare food in those, in fact pot-like, holes.
Today we can find those geomorphological forms, that clearly indicate the former presence of glacial ice, in a number of places in Sörmland’s landscape (and of course elsewhere as well). The title picture is taken on Gålö, an island in the southern archipelago of Stockholm. The following picture shows me next to the glacial pothole in Labro Ängar Nature Reserve (outside Nyköping) during a guided tour. Further examples of different sized cauldrons can be found near Tystberga, in Nynäs Nature Reserve and along the coast of Bråviken in southern Sörmland.

Fig 2: Me talking about the giant's pothole at Labro Ängar (2021).

Have you already seen giant’s potholes in Sweden or any other places around the world? You’re welcome to share your experience in the comments below.

There are no reviews yet.
© Stefanie Schlosser 2023
Stay curious and never stop learning
Back to content