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Baily— Cambrian Rocks and Fossils. 389 
of Dublin, may be reached by either of two lines of railway, which 
converge before entering the town. That through Kingstown, start- 
ing from the Dublin terminus in Westland Row, skirts the south 
coast of the beautiful Bay of Dublin; the other and most direct 
route being by the Dublin, Wicklow, and Wexford Railway from 
the terminus in Harcourt Street. In either case these railways com- 
mence in the Upper Carboniferous Limestone, upon which Dublin 
is built, continuing to run for about four miles over that formation. 
They then enter the boundary of the great granite-area, which is 
the largest display of that rock on the surface in the British Islands, 
crossing it at its northern extremity,—in one case, between two and 
three miles from the coast, fur a distance of nearly six miles —in the 
2 Fic. 1.—Bray HEAD, WicKLOW. (Looking North.) 
other, following to some extent the curvature of the coast to Kings- 
town, celebrated for its fine harbour, then proceeding about half a 
mile inland, until it again reaches the sea opposite the southern 
extremity of Dalkey Island, a distance of nearly five miles, where it 
enters upon the comparatively narrow belt of metamorphic rocks 
which flank the granite-axis, and forms the commencement of the 
Lower or Cambro-Silurian formation. These rocks continue for 
about another mile to the south side of Killiney Bay, where is 
believed to be the commencement of the Cambrian district of North 
Wicklow, about a mile north of the town of Bray; the shore and in- 
terior of the country, up to a certain height on the flanks of the hills, 
