Jezioro Hańcza : wstępne wyniki geologicznej interpretacji obrazów sonarowych

Preliminary interpretation of the geological structures on the eastern slope of Hañcza Lake was performed based on underwater sonography images. The studies were carried out on a 500-metres long part of the slope at a depth of 50 m. Underwater observations, sonography images and numerous photos were made by divers Pawe³ and Joanna Szpygiel. A preliminary geological interpretation shows the presence of glaciotectonic structures created as diapiric or anticlinal folds separated by synclinal parts. Diapiric or anticlinal folds are composed of massive tills with numerous boulders. Synclinal parts of the underwater slope probably consist of sands and silts. The section also reveals landslides and lowered parts of the sediments. The glaciotectonic structures originated probably as a result of the horizontal and vertical stresses exerted by the ice sheets of the Middle Polish Complex and Vistulian Glaciation. Additionally, Lake Hañcza and its surroundings were shaped by neotectonic phenomena related to the structural pattern of the old basement, as well as by deep permafrost processes.