Siccar Point Field Excursion Preview

Laurentia margin cross section at 425Ma

There was a subduction zone plunging towards the north-west beneath the margin of Laurentia. There was a trench somewhere south-east of what is now the Southern Uplands of Scotland. More below...

Blocks of sedimentary rock that accumulated in the trench were successively underthrust below previous blocks causing them to be rotated through steeper and steeper angles. The block at Siccar Point is now nearly vertical.