List of Caradoc ov Bala Fossils found 
in the Neighbourhood of Bala, Corwen, and 
Glon Ceiriog. 
BY THOMAS RUDDY, PALE, CORWEN. 
N the typical Bala district, the series is divisible into several 
zones or sub-divisions, each of which have characteristic 
fossils (see Section.) These zones are usually divided from 
each other by barren shaly beds, often ashy. which sometimes 
are of considerable thickness. The ashy beds are either fine 
and compact, or composed of breccia, and in the latter case 
are often calcareous, and yield an occasional fossil. 
The zones 2, 3, and the fossiliferous part of 4, do not occur 
at Bala, but they are highly developed in the mountains south 
of Corwen, and at Glyn Ceiriog, south of Llangollen. The 
zones 5, 6, 7, 8, are best developed at Bala and Glyn Ceiriog. 
Zone 9 is poorly represented in the mountains south of Corwen, 
but it is well developed further south at Milltir Gerig on the 
Bala and Llangynog road, under the eastern outcrop of the 
Bala limestone, and again near Bala in various places under 
the western outcrop of the Bala limestone. Its stratagraphical 
position is immediately above the ‘Little Ash”? (see Memoirs 
of Geological Survey, Vol. III., page 220), which may be seen 
on the Geological Maps as a narrow red streak running in a 
broken line, parallel to the blue line of the Bala limestone, and 
about 800 feet below the limestone. Zone 1 is best developed 
in the Hirnant Valley S.E. of Bala; it is known as the Hirnant 
bed, and is composed of fossiliferous sandy shales, compact 
grits, and a thin band of black Pisolitic limestone. A thick 
bed of blue slaty shales divides it from the Tarannon shales. 
- These same grits and blue slaty shales occur under the Tarannon 
shales at Corwen, but the pisolitic limestone and characteristic 
fossils are absent. 
We meet with a thin band of grey limestone at Glyn Ceiriog 
in zone 2, and a very thin concretionary grey limestone occurs 
in the same zone at Corwen. The compact grits and blue slaty 
shales again occur at Glyn Ceiriog above the upper limestone, 
and under the Tarannon shales. It might be inferred that the 
upper limestone at Glyn Ceiriog and the Hirnant limestone at 
