Anniversary Address to the Royal Geological Society. 2038 
covered unconformably by the Carboniferous Limestone at Castle- 
bar. He seems, in the paper now referred to, to speak somewhat 
uncertainly of the position of the Glengariff Grits. 
In 1844 Griffith read a paper to the British Association, at 
York, “On certain Silurian districts in Ireland.” There is a 
tract of fossiliferous Silurians N. and S. of Killary Harbour, 
bounded on the N. by Croagh Patrick, on the 8. by the Twelve 
Pins. He speaks of the fossiliferous Silurians of Waterford, 
Wexford, and Wicklow. These were all examined by him since 
August, 1843. We find that Oldham was working out these 
rocks, and obtaining fossils from them simultaneously. The 
large slate district of Down, Armagh, Monaghan, Cavan, and 
Louth is Silurian, probably all Lower Silurian, though no fossils 
have been obtained thence, except at its south border, at Grange- 
geeth, near Slane. 
He had concluded, by January, 1846, that the Transition rocks 
of the Galtees and of Slieve-na-muck are Lower Silurian. 
In August, 1853, the year of the Exhibition in Dublin, a small 
edition of the map on the scale of 1 inch to 16 miles was published to 
accompany the Instructions to the Valuators. A knowledge of the 
surface extent of the geological formations of the country was 
calculated to be of great use to the Valuation Survey; since the 
composition of the rocks, as a general, though not invariable, rule, 
affects so largely the character and value of the soil of a district. 
The correspondence of the boundaries of better and worse land 
with the geological outlines of a region is often most remarkable. 
A reissue of this map came out about a year afterwards which 
contained some slight additions. This map contained, as far as 
its scale would allow, all the improvements of which we have 
been speaking, together with some introduced by the Geological 
Survey, as the Cambrian areas of N. Wicklow and of S.E. Wexford. 
In February, 1854, Griffith received the Wollaston Medal from 
the Geological Society of London, “for the valuable services 
rendered by him to geological science, and particularly for 
his Geological Map of Ireland, the result of his own labours 
and judicious researches.” The President, Edward Forbes, in 
presenting the medal spoke of the map as “one of the most re- 
markable geological maps ever produced by a single geologist.” 
In 1855 a revised, and the last, edition of Griffith’s large map 
