A beautiful image of a forest reflected in a pool of water within a pothole in southern Finland is this Monday’s Imaggeo image and it brought to you by Mira Tammelin, a Finish researcher.
The photo illustrates a pothole in the Askola pothole area in southern Finland. The pothole area is situated on the steep slopes next to river Porvoonjoki, approximately 70 kilometers to the northeast from the capital city Helsinki and 30 kilometers to the north from the Gulf of Finland. The potholes are carved into an outcrop of Proterozoic rocks that is surrounded by boreal taiga forest, which consists of mainly of coniferous tress such as pine, spruce and larch.
Potholes are cylinder-shaped cavities that form when stones carried by water start to circle in an eddy and churn the surrounding rock for an extended period of time. The majority of Finnish potholes, including those in Askola, were formed under a melting continental ice sheet during the late stages of the last glaciation 13 000 – 10 000 years ago. The area is also archaeologically important as it is one of the first places in Finland where humans settled after the deglaciation.
The more or less 20 potholes in Askola vary in shapes and sizes and some of them belong to the largest in the world. The largest pothole in Askola, called The Giant’s Tub, is 4.2 meters wide and 10.3 meters deep. The pothole in the picture is one of the smaller potholes in the area with a diameter less than a meter. It has filled with rainwater thus reflecting a beautiful, sunny midsummer day.
By Mira Tammelin, Research Fellow at the University of Turku, Finland.
Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.