Cross Fell and the adjoining fells are mainly a bed of hard, carboniferous limestone. Where this bed surfaces, there are steep rock faces. There are also strata of shale and gritstone that surface on the fell. On the south and west facing slopes of Cross Fell the rock faces have been broken up by frost action to give a scree slope made up of large boulders. The local terrain shows obvious evidence of recent glaciation and is covered by thin soil and acidic peat.