In the Flandrian Fenland sediments of the Nar Valley, Norfolk, an upper clay and thick upper peat overlie lower clay and lower peat units thinning eastwards up the valley. Lithostratigraphic and altitudinal variations in less than thirty metres led to the application of a soil mechanics technique, the oedometer test, to the sediment units in order to estimate amounts of compression and corrections for the altitudinal displacements. The principles and assumptions behind the oedometer test are reviewed and results from compression tests on Flandrian Fenland deposits in the Nar Valley discussed in relation to interpretation of stratigraphic data, especially in terms of reconstruction of former sea levels. Limitations of the technique, particularly with reference to peats, are discussed.