Akademik

kettlehole
  a small depression usually found on the outwash plain of a glacial area and sometimes containing a small lake. As glaciers retreat, large blocks of ice detach and fall to the ground, embedding themselves to a certain degree. These blocks may then be covered in glacial and fluvioglacial debris which will form an even surface above. As the ice block melts, the ground above will subside.

Geography Dictionary & Glossary for Students \\ ITS Tutorial School (ITS) - Hong Kong.