The eastern portion of the peninsula is relatively flat, with the surface composed mainly of alluvial deposits of glacial origin, and altitudes not exceeding 200 m.  However, the western part is hillier and reaches 900 m at Mont Crozier near the isthmus. The hills and the slopes of Mont Crozier are olivine basalt with thicknesses up to 1000 m.  Some 55 km long, the peninsula is about 10 km wide at its western base and widens to more than 30 km across further east.
The eastern part of the peninsula is relatively flat, composed mainly of glacial deposits, and has elevations not exceeding 200 m. In contrast, the western section is hillier, reaching a height of 900 m at Mont Crozier near the isthmus. The hills and slopes of Mont Crozier are made of olivine basalt with thicknesses up to 1000 m.