Two models are presented for the formulation of abrasion and basal drag due to rock–rock friction (debris drag) for the case of sparse debris entrained in the basal layers of a temperate glacier resting on a bedrock bed. The first model is formulated in terms of average basal melting rate, v a, and the concentration, C, of basal debris fragments which make intermittent bed contact. The second model is formulated in terms of v n the component of ice velocity normal to the bed flowing around rock fragments contacting the bed, and C c, the concentration of debris actually in contact with the bed. The relationship between the two models is given for the case of a sinusoidal bed. Generalizations are discussed as well as potentially important physical processes which remain to be investigated.