During fieldwork, a volcanologist searches for clues about volcanic processes by examining the deposits left by an explosive eruption. The deposits contain valuable information about the impact that the eruption had on the local environment. This information is extracted by making careful observations about the grain size of particles, sorting (range of particle sizes in a specific layer) and the thickness of different layers.
Deposits from explosive eruptions are commonly arranged in layers. Each layer represents a specific type of volcanic process. It is important to remember that a single eruption may produce a number of different layers if the volcanic processes change during the course of the eruption. The lowermost layer typically represents the earliest phase of the eruption with subsequent layers stacked one on top of another. The sequence of events is thus read from the bottom to the top.
Just like a field volcanologist, you've been recording all of your observations in your own field notebook