This is a picture of a block and ash flow which can be seen throughout the city of St. Pierre. From these deposits, models of the eruptions have been proposed to explain the nature of the eruption in 1902. Lacroix concluded that a lateral blast came from the volcano and travelled to the city of St. Pierre. From the conclusions of Fisher and Heiken's more detailed analysis a revised model was determined. Their model consisted of a vertical ejection of a dense eruption column that eventually collapsed and tunnelled through the valley of the Riviere Blanche. Other volcanologists who have studied the eruption have proposed alternative theories thus continuing the ongoing debate of the exact nature of the flow.