In this paper we define stratotypes for glacial and associated sediments in southern and western Finland. The Kauhajoki Formation in southern Ostrobothnia (Pohjanmaa) and the Kela Formation in western Uusimaa, comprise a complex sequence of sediments deposited during the Weichselian glaciation. Following the entrainment of debris by the first advancing ice, the deposition was initiated by lodgement of the Kauhajoki and Siuntio Tills. The ice was flowing towards the south. Later, during the deglaciation, deposition was largely by basal melt-out leaving the Espoo Till in western Uusimaa. The Pikkala Sands, sandwiched between the underlying till and overlying Espoo Till were deposited by subglacial meltwater. A comparable facies change, from lodgement to melt-out, is also recorded in the uppermost 1 metre of the Kauhajoki Till. Other lithostratotypes are proposed for sediments underlying till (the so-called 'old' glaciofluvial and associated sediments) in southern Ostrobothnia. These include the Harrinkangas Formation. The approach of using formal lithostratigraphical units is recommended because of the complexity and wide extent of the Pleistocene deposits of Finland. As a consequence of the present lack of bio- or chronostratigraphical data in southernmost Finland, the classification and subdivisions of stratigraphic units based on cold stage sediments requires detailed sedimentological analysis.