A biostratigraphy for the London Clay in London

Biostratigraphy enables specific layers of strata to be given a unique stratigraphic address that can be used to identify the horizons in which in situ tests are conducted and from which samples for testing are collected. This is particularly valuable when working in fine-grained deposits, where stratigraphic position is not easily recognised by lithology alone, and permits any data bank of geotechnical values and performance to be used without fear of confusing one stratigraphic layer with another. Construction in the London Clay Formation, and its supporting research, has necessitated an accurate and speedy method for identifying, with a precision of centimetres, the stratigraphic layer from which geotechnical data have been obtained. The principles that enable biostratigraphy to be used for this purpose are explained and illustrated with reference to the London Clay Formation in London: this approach can be used in most sedimentary strata. An example of biostratigraphic data used in London is presented.