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Geological Relations of the East of Ireland. 
§ 126. In following the coast from Balbriggan to Skerries, we 
observe a cove to the south of the pier, the banks of which are 
occupied by alluvial soil and calcareous tuff ; but in the projecting 
headland beyond, massy greenstone strata, three, four, and five feet 
thick, appear, ranging 30° north of east and south of west, and dip- 
ping 30° toward the south-east. These are succeeded on the south 
side of the headland by alternations of greenstone, (much mixed 
with calcareous matter,) and slaty greenstone passing into clay slate, 
followed by repeated alternations of fine grained greywacke, with 
clay slate and greywacke slate, lining the coast as far as the town of 
Skerries. Some of the slaty rocks vary in colour from pale bluish 
grey to deep bluish black, and finely disseminated iron pyrites is 
common in the greenstone and greywacke, both to the north and 
south of Balbriggan. 
In these alternations, sometimes the greywacke beds predominate 
and sometimes the slaty beds, varying from a few inches to five 
feet thick. To the south of the greenstone promontory, they range 
for a considerable distance pretty regularly east and West, dipping 
57° south. Subsequently, they range 25° south of east and north 
of west, dipping 35° to 40° toward the west of south, but on 
approaching the projecting ledge of loose blocks, called the Long 
Leg , they become singularly inflected and contorted, and the surface 
of the rocks having been broken away, they much resemble in 
aspect the agitated waves of the ocean. But they subside ulti- 
mately into a more regular arrangement, gradually rising to the 
south-westward, under an angle of 15°, and retaining that position 
for a considerable distance in parallel order, the greywacke beds, 
which predominate, being separated by thinner beds of slate. 
These rocks form the north side of a cove, the banks of which are 
composed of alluvial soil, but they re-appear in the eastern point, 
Vol. V. 2 G 
