suur, ebasümmeetrilise tilga kujuline, liustiku liikumise suunas orienteeritud positiivne liustiku kulutusvorm aluskivimis, bedrock knob or hill formed by glacial erosion that is completely streamlined on the gentle stoss (upstream) side and plucking on the higher lee (downstream) side that is hundreds of metres long. Rock drumlin is formed when a glacier or ice sheet passes over an area that contains a particularly resistant rock formation. The force of the glacier erodes the surrounding softer material, leaving the rocky block protruding from the surrounding terrain.