Vol. 62.] TARANNON SERIES OF TARANNON. 665 



Talerddig Group (Be). — For a distance of about a quarter of 

 a mile to the north and south of the village of Talerddig we find 

 everywhere evidences of the presence of the Talerddig Group. 

 The strata dip in a general north-westerly direction, and disappear 

 below the overlying Dolgau Beds between Dolgoch and Pandy-bach. 

 The most complete section of the Talerddig Beds in this part of 

 the district is that exposed in the railway- cutting north of Talerddig 

 siding. Here the beds, which dip at angles of 42° to 48° north- 

 westward, consist of alternations of grit- and shale-bands, similar 

 on the whole to those exposed along the Tarannon River, but 

 differing somewhat in the details of their lithology and thickness. 

 They are divisible into the following rock-bands, arranged in 

 descending order : — 



Thickness in feet. 



9. Shale-band (e) 60 to 70 (incomplete). 



8. Grit-band (d). 



i. Grits 12-) 



ii. Shales ,... 14 | 



iii. Grits 55 y 113 



iv. Shales 8 | 



v. Grits 24j 



7. Shale-band (d) 35 



6. Grit-band (c) 40 



5. Shale-band (c) 36 



4. Grit- band (b) 33 



3. Shale-band {b) 60 



2. Grit-band (a) 30 



1. Shale-band (a) 40 (incomplete). 



The lowest beds exposed in the railway-cutting consist of shales 

 and thin flags ; their base is not seen, for the rocks are here 

 obscured by vegetation. The first grit-band (a) shown includes 

 among others a grit of about 4 feet in thickness. Evidences of 

 disturbance of the strata are apparent on the eastern side of the 

 cutting, where one of the grits is seen to be twisted and fractured. 

 The grit-bands (6) and (c) agree closely in character and thickness 

 with the 3rd and 4th grit-bands in the Tarannon section. Where 

 they crop out at the surface on the eastern side, they form pro- 

 jecting cornices, while the intervening shales occupy a deep recess. 

 Some of the grits which belong to grit-band (b) are also well shown 

 in a small quarry, some 50 or 60 yards to the east of the railway. 



A few graptolites were found in the shale-band intervening 

 between the grit-bands (c) and (d). They include the following- 

 typical Talerddig species : — 



Monograptus priodon. 

 Monograptus griestonensis. 



Monograptus subconicus. 



Monograptus discus. 

 Monograptus nudus. 



The highest grit-band met with answers apparently to the 5th 

 in the Tarannon section, and, like that, is the thickest. It contains 

 several strong grits, and forms a prominent feature on the western 

 side of the cutting just below the railway-bridge. 



This grit-band is overlain by a shale-band, of which more than 



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