Edinburgh Castle is an ancient monument situated on a basalt crag which has steep cliffs falling away on three of its sides. Periodically, remedial measures have to be carried out on these cliffs by engineering geologists in order to stabilise loosened parts of the surface and thus prevent rock falls occurring. The rock structure on the sheer north‐facing cliff is currently being studied to determine the extent of work required to ensure its stability. Before such a study could proceed satisfactorily it was necessary to obtain a large scale, contoured survey of the face and this has been achieved by terrestrial photogrammetric methods. Stereoscopic photography was taken with a Wild RC5A wide angle camera pointing horizontally, being specially mounted on its side in the elevated bucket of a Simon hydraulic platform, positioned 17 metres above ground level at a distance of 100 metres from the rock face and at eight successive locations in West Princes Street Gardens. The elevation was plotted with a Zeiss Stereoplanigraph C8 at a scale of 1 : 50 with contours (with respect to a vertical datum) at horizontal intervals of 250 mm.

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