Page:Quarterly Journal of the Geological Society of London, vol. 35.djvu/854

714 14 PROF. E. HULL ON THE DINGLE BEDS AND T3 k" CQ H 1 -OU/LT 2 M t

s * fcHl ^ r^ 8 * fossiliferous to place their age be- yond question, and rising into lofty and rugged elevations like those we have been consider- ing in Kerry. Amongst these is Mweelrea, the highest mountain in the west of Ireland, rising 2688 feet from the level of the sea. So similar are the rocks of this dis- trict to the " Dingle " or " Glen- gariff series," that the general de- scription of one set would be ap- plicable to the other. The Tipper Silurian rocks of West Galway and Mayo (fig. 9) consist of a great series of grits and conglo- merates, purple and green slates, with beds of conglomerate and limestone towards the base. They contain sheets of felstone porphyry and ash of contemporaneous origin, and are fossiliferous at intervals throughout. These beds, which are of great (but unknown) thick- ness, comprise the Upper Silurian series from the Llandovery stage upwards into the Wenlock and Ludlow stages ; but, as observed by Sir It. I. Murchison, it is im- possible in the west of Ireland to separate the Upper Silurian series into those well-marked stages, cha- racterized by beds of limestone and special fossils, which he himself originally recognized in the Silu- rian region. The Upper Silurian beds rest everywhere discordantly upon a floor of more or less meta- morphosed Lower Silurian rocks, filling in old valleys and depres- sions, and often containing pebbles derived from the older formations. Mr. Kinahan separates the series into divisions, which are probably represented in Dingle and Kerry as under * : — (1878).
 * Expl. Mem. sheets 93, 94, &c, p. 15