In this report the physical volcanology, petrology, and geochemistry of the Coopers Knob area of Lyttelton Volcano are described. Activity of the Lyttelton volcano is represented by basaltic lava flows, basaltic to trachytic dikes and endogenous domes, pyroclastic units, and scoria cones. Activity of the Diamond Harbour Volcanic Group is represented by a basanite volcanic plug and small endogenous dome. Lavas and dikes are dominantly plagioclase-olivine-pyroxene-phyric basalts and hawaiites with subordinate mugearite and trachyte dikes. Pyroclastic units represent strombolian and minor phreato-magmatic activity which increases in frequency towards the top of the sequence. The Gibraltar Rock intrusion formed in at least two stages as a result of dike emplacement and expansion or interaction with the surface. Thimble Rock resulted from the single stage intrusion of a dike in weak country rock. The Coopers Knob basalt to trachyte suite belongs to the Lyttelton Volcanic Group which forms a mildly alkaline to sub-alkaline sodic series. Crystal fractionation is considered to be the dominant petrogenetic process for relating mafic-felsic compositions. Basal lavas and evolved mugearites have low Nb/Zr ratios and show little sign of modification by crustal contamination. Basanite samples belong to the Diamond Harbour basanite to ne-hawaiite trend and are moderately undersaturated and nepheline-normative suggesting that they are not related by crystal fractionation to the Lyttelton volcanic group. Initial basanites underwent limited crustal contamination and fractionation while later magmas progressively interacted with crustal rocks resulting in' selective contamination.