Worksheet 3: Microscopic Sea Level Recorders

This resource considers what the microscopic plants and animals found over a salt marsh can show about past sea levels. The two activities in this resource explore these microscopic sea level recorders and how researchers use them to understand sea-level change.

In the first activity, students explore the distribution of species across a salt marsh. A sheet is provided which contains a variety of diatoms, single-celled plants (alga) which have a cell wall of silica. These can be cut out and stuck to the blank salt marsh transect to encourage students to think about species distribution across the marsh.

In the next activity, students use the map of modern diatoms across a salt marsh that they have created to interpret the changes in the fossil core on the Microfossils in a Core activity sheet. Using a core, it is possible to understand how sea level has changed based on the preserved microfossils. This can be more effective than looking at different coloured sediments as, although this provides a broad pattern of change, foraminifera and diatoms record more subtle changes in environment, even within one coloured sediment type.

This resource was produced by the Geography Department at the University of Durham.