The entire hill is formed from Ordovician-age rocks assigned to the Skiddaw Group. The summit ridge and northern slopes are composed of the laminated mudstone and siltstone of the Kirkstile Formation, whilst the summit knobble and southern slopes are formed from the Buttermere Formation, an olistostrome of disrupted, sheared and folded mudstone, siltstone and sandstone. The eastern spur and Rowling End reveal the large olistoliths of greywacke sandstone of the Robinson Member, a sub-unit of the Buttermere Formation.