The contact relationship between volcanic deposits and surrounding country rocks of the Beacon Supergroup are steep over a large area. Beyond the landslide deposits along the contact between Beacon country rock and Mawson volcaniclastic rocks lies the Mawson itself. An area in which the remains of a single vent of the vent complex was well exposed, on both steep and subhorizontal ground surfaces, ... was mapped in detail with the geometric relationships between different bodies of volcaniclastic rock examined. The characteristics of the processes that cause one body of debris to be apparently shot through the other was investigated. Standard geological mapping techniques, photographs, scaled sketches and rock samples were used to create a 3-dimensional reconstruction of the record of volcanic processes within the vent of a large and explosive basaltic eruption.