I0 8 Swanston— Silurian Rocks of Co. Down. 
do more than notice the rocks which occupy the north-eastern portion of the 
area situated wholly in the County Down. 
PREVIOUS NOTICES OF THE DISTRICT. 
Perhaps the earliest reference to the rocks of this area is that by Drs. 
Berger and Conybeare, made in 1816. (i) These pioneers of Irish Geology 
pointed out the similarity between the County Down rocks and those of South 
Scotland. On the large geological map compiled by Sir Richard Griffith in 1839 
the area is put down as Clay-slate or Greywacke-slate belonging to the Transition 
series. Dr. Bryce in 1852 stated as follows (2) ' “The County Down con- 
tained two granitic tracts which seem to have been elevated at different epochs. 
They are separated from one another, and each is wholly enclosed by a thick 
band of metamorphic slate, gneissose in its lower part, and passing upwards 
into flinty and common clay-slate. Superimposed conformably upon these are 
other slates of less crystalline type, whose aggregate thickness is enormous, 
and whose upper portions have yielded a few imperfect fossils, which seem to 
make them referable to the Lower Silurian Group ; but as yet no definite line 
has been made out to justify a classification.” Sir Roderic Murchison states 
in 1854 (3) : — “ It is believed that the Schists of Down are of the same age as 
the Graptolitic Schists of Wigton and Galloway. ” J . Beete Jukes, F. R. S., after 
referring to the Chair of Kildare, which contains Bala fossils (4), states that 
“ another great tract of apparently similar beds stretches from the centre of Ire- 
land, Cavan, &c., to the coast of Down. Among these, however, a portion 
certainly belongs to the Llandeilo Flags, as near Bellewstown, on the confines 
of Dublin and Meath, an assemblage of Llandeilo fossils were found. 
Many years ago it was known to members of the Club that Graptolites 
occurred in the County Down, and specimens were obtained by them at Tully- 
garvan, near Saintfield, from the debris of a shaft which was there sunk in the 
Silurian rocks in search for coals (5); none were, however, sufficiently perfect for 
identification. 
(1) . Transactions of the Geological Society of London, Vol. III. 
(2) . Report of the British Association (1852). 
(3) . Siluria (1854)— foot note, p. 166. 
(4) . Manual of Geology (1862), p. 454. 
(5) . The slightest knowledge of the evidence furnished by these fossils would have saved a 
vast amount of useless expenditure and misdirected efforts here, and at many other localities 
throughout the district. The projectors in their search for coals were doubtless imsled by the 
resemblance of the black Graptolitic bands to the rich carbonaceous shales of the Coal 
Measures. 
