The setting sun enhances this view of the different rock strata in the cutting leading to the North Portal of Whitrope Tunnel north of where the retaining wall ends. The geological sequences are similar to those at Siccar Point in Berwickshire and are known as Hutton's Uncomformity https://www.edinburghgeolsoc.org/edinburghs-geology/huttons-unconformity/
This discontinuity in the sequence of strata was used by James Hutton (1726-1797), the Father of Geology, to demonstrate earth movements and the time gap which the unconformity represented; he deduced from this the enormity of geological time itself. In this case we see specifically: the tilting and folding of sedimentary rock layers (shaded lower rocks, Silurian 435 million years old), erosion of these and deposition of much later sedimentary layers (upper rocks in sunlight Upper Devonian 370 million years old) on top of the eroded surface (dark area below the overhang) and subsequent tilting of the entire sequence of rocks. More details and photos of these rocks within the tunnel itself are available here: http://www.forgottenrelics.co.uk/tunnels/whitrope.html

Location: Whitrope Tunnel (former)

Original line: Border Union Railway (North British Railway)

Photographer: Charlie Niven

Contact photographer: Charlie Niven

Contact editor

Date: 11/1993

Image number: 73979

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