390 Baily— Cambrian Rocks and Fossils. 
being covered with drift of sand and gravel, so as to conceal the 
underlying rocks.* 
From the Bray Railway station, a walk along the shore of about a 
mile brings us to the commencement of the series of rocks forming 
the bold and picturesque promontory of Bray Head, which rises in 
sombre majesty from the sea to a height of nearly 800 feet. The 
railway is continued through this apparently impenetrable mass 
of rocks by several short tunnels and cuttings, passing over the 
chasms by bridges or viaducts, and aiding the geologist, as it gene- 
rally does, by exposing fine sections of the strata, exhibiting occa- 
sional breaks or fawlts in its continuity, and the variety of inclination 
or dip, curvature or contortion, to which the beds have been sub- 
jected, as well as adding considerably to the picturesque effect of this 
prominent part of the coast when observed from the sea. 
The sketch on the preceding page (fig. 1) may serve to give some 
idea of the appearance these rocks present, with the general con- 
figuration of the hill towards the sea. 
2 miles. 1 mile. 
Fic. 2. DIAGRAMMATIC SECTION OF THE CAMBRIAN ROCKS AT BRAY HEAD. 
* Quartz Rock. 6. Cambrian grits and slates. 
(General dip, about 45° to 80° NE. Horizontal scale, about 14 inches to the mile; vertical scale, 
twice that of the horizontal.) 
A diagrammatic section of this part of the coast is given above 
(fig. 2), showing in a rough way the general dip of the strata with 
their convolutions, and the interpolation of irregular masses of quartz, 
on a scale (horizontally) of about one and a half inches to the mile, 
the vertical scale being twice that of the horizontal. The beds, con- 
sisting of green and purple grits and slates, mostly dip towards the 
NE., at a high angle, varying from 45° to 80°, are often much 
contorted, and occasionally interstratified with veins and masses of 
white and yellowish quartz. ‘This rock forms the most prominent 
parts of the hill, and some of the beds may be traced down to the 
section exposed on the shore (they are represented in fig. 2, at *, by 
crossed lines). It is in these grits and slates, at several places along 
this part of the coast, that the remarkable little branching or plant- 
like fossils called Oldhamia, before alluded to, have been met with, 
sometimes occurring in great profusion, although they have never 
yet been found in England or Wales. 
In walking along the shore from Bray towards the Head, the first 
— 
* Vide sheet 121, one-inch scale, Maps of the Geological Survey of Ireland, 
