ON EXCAVATIONS IN THE PALEOZOIC ROCKS OF WALES, ETC. 115 



Excavation No. 23. 



The surface feature made by the outcrop of the Shoot Rough Road 

 Flags is traceable in a north-westerly direction for about 100 yards 

 from excavation No. 20. A trench was opened across this feature and 

 continued south-westerly to ascertain, if possible, the nature of the beds 

 underlying the flags. At about 18 feet below the top of the flags a band 

 of rotten stone was touched, yielding residual nodules of calcareous 

 sandstone, and containing plentiful remains of Paradoxides rugulosus 

 Corda. At about the horizon of this bed the flags graduate into a soft 

 greenish micaceous sandstone, like that noticed at the east end of exca- 

 vation No. 21. 1 A thickness of 3 feet of this sandstone, now called the 

 ' Shoot Rough Road Sandstone,' was exposed, but its further down- 

 ward continuation could not be ascertained, owing to the increasing 

 thickness of detrital matter from the escarpment of the flags above. 

 With the help of my friends, Rev. W. M. D. La Touche and Mr. C. I). 

 Walton, I secured further fossils from the flags of the original section 

 (No. 20); they include a small Microdiscus very like M. punctatus, form 

 eucentrus Linn., but not sufficiently well preserved to identify with 

 certainty, and a form recalling Ptychoparia (Liostracus) Linnarssoni 

 Brogger. 



Combining the observations of 1908 and 1909, the complete section 

 across these Shoot Rough Road Flags may be summarised thus : — 



a. Shoot Rough Road Shales (top not seen) 40 feet 



b. 2 Shoot Rough Road Flags 18 feet 



Additional fossils — Microdiscvs, sp., cf. M. cnccntra or M. punctalus 

 Salter — Ptychoparia Linnarssoni Brogger ? and 



c. Shoot Rough Road Sandstone 1 foot 



Ci Calcareous band Paradoxides rugvlosus Corda, ' Lingulella- 



ferruginea Salter, Acrotre ta or Acrothele, sp.' 3 .... 1 foot 

 c a Green Sandstone (base not seen) 3 feet 



Excavation No. 21, Shoot Rough Road, Lower Section. 4 ' 



In order to examine the nature of the junction of the shales and 

 gritty flags of this lower section a trench was opened parallel to the 

 original exposure, but at a distance of 5 or 6 feet, and on the other 

 side of the hedge, where it was possible to excavate to a depth of about 

 5 feet without danger. The new section disclosed was as follows : — 



West End of the Section. 



a. Shales comparable with the Shoot Rough Road Shales of the upper 

 section dipping at a very high angle to the east-north east (top not 



seen) 9 feet 



b. Gritty flags and rotten stone bands — 



b t . Red earthy rotten stone .5 feet 



b . Flaggy, sandy bed, dip vertical 3 feet 



b ,. Hard greenish bed of grit, dip c\ 80° north-west . ... 1 foot 

 b t . Flaggy beds with shale partings (base not seen) .... 5 feet 



1 Brit. Assoc. Report, 1909 (Winnipeg), p. 185. 



2 Details of those flags are given in the previous report, op. cit., p. 184. • ■ 



s The determinations of the Brachiopods included in inverted commas are those 

 supplied to mo by Dr. C. A. Matley. 



4 Brit. Assoc. Report, 1909 (Winnipeg), p. 185. 



i 2 



