ON EXCAVATIONS IN THE PALEOZOIC ROCKS OF WALES, ETC. 119 



defined, 1 and that it is overlain unconformably by the conglomeratic 

 Quarry Ridge grits of Paradoxides age. Further excavations between 

 those numbered 29a and 29d are urgently required. 



Excavations Nos. 30 and 35, at the foot of the North-West Slope of 



Bobin's Tump. 



No. 30. — A natural exposure of Lower Comley sandstone close to 

 the stream was opened out and followed along the strike for about 

 15 yards. The rock consists of some 6 or 8 feet of greenish micaceous 

 sandstone, dipping at 45° to 50° to the east-south-east, and having 

 numerous cross fractures at right angles to the strike. About midway 

 in the sandstone was a band of clayey material, which on being worked 

 yielded residual nodules of rottenstone and sandy, foraminiferal (?) 

 limestone containing many specimens of a Hyolithus approaching to the 

 form H. fistula Holl. From this band one external cast of a head shield 

 of an Olenellus (apparently an undescribed species) and a few other 

 trilobitic fragments were collected. The band could only be followed 

 for 3 or 4 feet along the strike, and appeared to thin out in the direction 

 of the dip. Both it and the sandstone contain numerous examples of 

 two forms of burrows. Those of form A are subquadrangular in section, 

 with diameters of from 8 to 12 mm. that remain sensibly the same in 

 the short lengths of the specimens collected, and have clearly defined, 

 brown-stained surfaces. Those of form B are much smaller sinuous 

 cavities, without clearly defined boundaries, generally filled with carbo- 

 nate, but near the surface, with brown earthy matter or roots of 

 plants; they have diameters of about 2 mm. 



No. 31. — About 30 yards to the north-east of No. 30. — A second 

 natural exposure of similar rock was opened out and elongated up the 

 steep slope of the hill so as to cross the bedding at right angles. About 

 23 feet of beds of greenish micaceous sandstone, varying a little in 

 toughness and becoming reddish purple at the top, were thus exposed, 

 and the dip was observed to remain steadily at 45° to 50° to the south- 

 east. 



No. 32. — About 45 yards further towards the north-east. — A small 

 natural exposure was cleared of soil and vegetation, and proved to con- 

 sist of reddish purple micaceous sandstone of the same aspect as that 

 at the top of No. 31. The dip, however, has in the interval worked 

 round from south-east to nearly south. 



No. 33. — 10 yards further to the north-east. — Similar rock but of 

 the usual greenish colour was seen here and the dip found to be about 

 5° to a little west of south. 



A r o. 34. — 60 yards distant from the last to the north-east. — Similar 

 greenish rock, but rather softer, was seen, and the dip has reverted to 

 the more normal one of about 45° to the east-south-east. 



No. 35. — In the extreme north-east corner of the fences bounding 

 the Robins Tump area. — Very fragmentary greenish sandstone was 

 observed at this point; and on opening it out there were obscure indica- 

 tions of a south-easterly dip. 



' Brit. Assoc. Report. 1908 (Dublin), p. 235, ct s<q. 



