OR/15/035 Model assumptions, geological rules used etc

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Thompson, J F. 2015. Model metadata report for HS2 Area 4. British Geological Survey Internal Report, OR/15/035.

Outcrop changes

In light of borehole interpretation, it was necessary to make some small changes to the outcrop of some units, this is illustrated in Figure 2 (the original DiGMAP extract) and Figure 3 (the geological units used in model calculation).

Figure 2 Example of small changes to outcrop, DIGMAP extract.
Figure 3 Example of small changes to outcrop, Geological Units as used in the model calculation.

Marlstone rock formation

In the southwest of the model, around Middleton Cheney (SP44SE, SP54SW) there is a dense grid of bores for ironstone, into the Marlstone Rock Formation. Base of MRB was taken at the base of the lowest significant ironstone bed (>0.15 m) (also agreed with Mark Barron who modelled Area 3).