The area covered by the lake was still glacierized in 1967. In that year, a rock slide occurred. The rear part of the slide was not very mobile and still appears as a large step in the landscape (left portion of the photo), whereas the frontal part evolved into a landslide cascade: it impacted the glacier, and the resulting avalanche of rock and entrained ice led to the drainage of a former proglacial lake, reshaping of the landscape below, and a distal flood in the river Markarfljót.