Professor Dennis Wood
contemplates the palaeozoic dyke beneath the lighthouse
A close-up of part of the lighthouse dyke, which presents as a sill
The lighthouse crag is another rich exposure of the Skerries conglomerate
A remarkable boulder in the crag above the dyke. Prof. Wood wondered if the parallel
striae
it bears were ice-worn, from the time of 'snowball earth'
Greenly studied the dyke and everything else on his visit to the Skerries in 1910-11. The
diagram
is from his great Anglesey Geology Memoir of 1919
The approach to the lighthouse crag, the dyke and conglomerate exposures is to the right
The approach to the lighthouse crag, the dyke and conglomerate exposures
The lighthouse crag is another rich exposure of the Skerries conglomerate but with less
granitoid material than at Ynys Arw