344 Mr. Weaver's Geological Observations on 



traversed by small contemporaneous veins and strings of calcareous spar^ 

 which mostly range in the line of the dip ; while some may be observed pro- 

 ceeding- from a common trunk, ramifying upwards into filaments, and finally 

 closing and disappearing in the solid limestone above ; much in the same man- 

 ner as granite veins are sometimes found to arise from a body of granite and to 

 penetrate into superincumbent slate. I noticed this fact in particular, in the 

 limestone quarry of the cliff situate in the dell beyond the southern extremity 

 of Tortworth Park. 



In the Tortworth district, many of the strata of the carboniferous limestone 

 appear to be destitute of organic substances ; but in some these form par- 

 ticular assemblages, in others they are thinly scattered. I have observed the 

 following : of univalves not chambered. Cirrus acutus, and a depressed species 

 of Cirrus, with circular whorls, approaching in form to that of an Euomphalus ; 

 a species of Helix, a Melania, and a Turbo ; of bivalves, anomites, terebratu- 

 lites, spiriferites, and productites ; of echinites, the spines only ; of crinoidea, 

 such remains as are chiefly referable to actinocrinites ; and of the coralloid 

 order, caryophyllites, madreporites, tubiporites, and reteporites. 



I have also remarked, on the separating surfaces of the small sandstone beds, 

 impressions and casts of caryophyllites, terebratulites, and entrochites, both in 

 the Tytherington ridge, and on the opposite side of the basin ; and again, 

 with vegetable remains also, on the northern side of the sandstone ridge on 

 which stands the church of Cromhall. 



§ 23. The limestone with the included beds of sandstone, now described, 

 is succeeded by a broad belt of sandstone, which dips, 



in the northern part of the field 10" to 16° to the S. 35° W. 



the north-eastern . 28° 31° . W.30° S. 



the north-western . . 30° . . S. 20° E. 



This belt contains limestone and sandstone conglomerate, in beds appa- 

 rently incidental, since their continuity is not traceable to the east and west; 

 and on the other hand, the limestone which occurs south of Cromhall church, 

 seems to be, in a manner, interlocked with sandstone. 



This broad belt of sandstone and conglomerate, immediately surrounding 

 the coal-field, agrees in many of its characters with the fundamental old red 

 sandstone and conglomerate. It is however, free from clayey or marly beds, 

 and varies from the state of a fine and minute-granular rock to that of compact 

 quartzy sandstone, or hornstone. In a small superficial quarry, opened to the 

 east of Cromhall Rectory, it exhibits relations that deserve attention, the fol- 

 lowing beds appearing : — 



