Very few geological research has been undergone on the Kati formation due to its scarcity of natural outcrops and complexity. The heavily weathered and limited number of natural outcrops available around the areas of Bandar Seri Iskandar and Parit (Perak) may help to define the Kati Formation in a more clear way. After recent human construction activities, more exposures can be studied, which makes easier the process of gathering geological information. The Kati Formation inspires quite a few questions to the scientific community, such as the source of the iron oxide extensively found on it and the processes that turned a softer shale into hard concretions, the presence of trace fossils as the only palaeontological evidences preserved in this heavily replaced rock unit, and the age of the overlying quaternary deposits, which is a key for understanding, in turn, the succeeding diagenetic processes. The objective of this research is to better define the Kati Formation in relationship to their associated quaternary materials, Mesozoic granites and metamorphic rocks, all by using classical stratigraphic methods first. © Published under licence by IOP Publishing Ltd.