706 PROF. E. HULL ON THE DINGLE BEDS AND 
Some of these fossils range upwards from the Caradoc or Bala 
stage: but the majority are solely Upper Silurian forms, ranging 
from the Llandovery to the Ludlow stages. 
On examining the specimens in the collection of the Geological 
Survey, it appeared to me that the fossiliferous portions of the rock 
were curiously mixed up with fragments derived from metamorphic 
strata, such as quartz, mica-schist, &c., with which they could have 
no connexion. There can be no difficulty in accounting for the 
presence of such pebbles, as all the rocks older than the Llandovery 
stage are metamorphosed in the west of Ireland, and they probably 
formed the land-surfaces of the Upper Silurian period*. But how 
are we to account for masses of coral, broken shells, and crinoids of 
Upper Silurian age, in company with such rolled and transported 
blocks? Many of these fossiliferous masses are angular, friable, and 
evidently not far removed from their original position. They could 
not have been derived from the fossiliferous Upper Silurian beds 
which crop out on the north-west coast, because these were buried 
underneath by several thousand feet of conformable strata. The con- 
clusion, therefore, that I have come to regarding their presence is 
that they were really formed in situ, in immediate proximity to the 
place where they are found, but have been loosened, drifted, and 
somewhat broken up by the current-action, which carried the 
pebbles of older metamorphosed rocks, and strewed them over the 
sea-hottom. 
I may add that the occurrence of this conglomerate is not re- 
garded by Sir R. Griffith as an obstacle to the acceptance of the view 
of the Silurian age of the “‘ Dingle beds.” He remarks, ‘“ Cases of 
derivative rocks sometimes occur in the same continuous series ; and 
such cases are rather to be expected, if we suppose the existence, at 
points not far distant, of the contemporaneous operation of agencies 
of denudation and deposition” +. On the whole it is impossible to 
suppose that these fossiliferous fragments could have come from 
strata of the Llandovery and Wenlock stages, which were buried 
under several thousand feet of these same “ Dingle beds,” both forma- 
tions being conformable. 
b. Killarney, Kenmare, Sneem, and Glengariff districts. 
That the main mass of the Dingle beds reappears in the promon- 
tories of Iveragh, Dunkerron, and Bear, rising into the highest 
elevations of the south-western highlands, is now universally ad- 
mitted, and cannot be questioned. The rocks are similar in cha- 
racter, consisting of hard massive green grits, sometimes conglome- 
ratic, surmounted by great beds of purple slate with bands of grit. 
Whatever, therefore, may be the age of the Dingle beds in the 
promontory of Dingle, such will it be in the districts of Killarney, 
Kenmare, and Glengariff. 
A difficulty has, however, been experienced by both Griffith and 
the Geological Surveyors in the attempt to separate these beds from 
* See ‘Physical Geology and Geography of Ireland,’ pp. 21-25. 
+ Journ. Geol. Soc. Dubl. yol. viii. p. 11. 
