658 REPORT— 1888. 



sandy heia •which are best, developed in the Forest of Dean. These consist of 

 micaceous green shales, and red purple and yellow sandstones. Some are cal- 

 ciferous and readily efferTesce when treated with acid. No fossils have been 

 found, but quartz pebbles occur in some of the beds. 



The strata just referred to pass up into limestone and shales, the so-called 

 Lower Limestone Shales. In the Forest of Dean the limestones are largely made 

 up of the valves of Ostrocoda, among which the following have been determined : 

 Kirkhya variabilis, K. plicata, Cytherella e.vtuherata, Bythocypris sublunata, and 

 Darioinula herniciana (?). Among the other fossils which are numerous may be 

 vaentionei Af/iyrisJRoyssii,Ii/iync/ionella2]leu>-odo7i,Encrinites and Folyzoa. Among 

 the latter the following have been determined : Rhabdomeson yracile, Phill., and 

 Fenestella tuherculocarinata. Ether. Junr. In the Lower Limestone Shales of the 

 Bristol coalfield Ostracoda are not so plentiful, though in some beds the valves of 

 these small Crustacea are numerous. Rhynchonella pleitrodon, Athyris Royssii, 

 Productus, Spin/era Crinoids and Polyzoa occur. At Clifton the Lower Shales 

 are followed by a crinoidal limestone known as the Black Rock, which is about 

 490 feet thick, and is not represented in the Forest of Dean. The Black Rock series 

 are followed by seventy feet of Dolomite, and then by about 100 feet of white oolitic 

 limestone which the author regards as the true base of the Middle or Carboniferous 

 Limestone. The author has grouped the Lower Limestone Shales with the Black 

 Rock under the term Lower Limestones, and he considers the stage to occupy the 

 horizon of the Tuedian and Calciferous series of the north of England and Scotliind. 

 As to the sandy beds which lie between the Old Red Conglomerate and Lower Lime- 

 stone Shales the author regards them as the equivalent of the lower portion of the 

 Transitional series of Phiitlips and the Calciferous of Scotland. The true upper 

 limits of the Old Red Sandstone should be drawn at the Old Red Conglomerate. 



As to the Middle Limestone there can be no doubt that it is the equivalent of 

 the Carboniferous Limestone as generally understood, but the latter term the author 

 thinks objectionable, and he would term the whole series Carboniferous Limestone. 

 The Middle Limestone is largely made up of Foraminifera and Calcisphcera , but 

 corals, polyzoa, crinoids, and shells occur, sometimes in quantity. In the Forest 

 of Dean the Middle Limestone is extensively dolomitised. 



Coming to the Upper Limestones ; at Clifton it is difficult to draw the line at 

 which the series should commence, as tliere is little alteration in the structure 

 from that of the Middle Limestones. Corals are more numerous, coarse oolitic 

 beds appear, and the beds become mixed with millstone grit. In the Forest of 

 Dean the upper stage is well and clearly defined by two characteristic lime- 

 stones known as the ' Crease ' and ' Whitehead.' The former of these has become 

 partially crystallised, but in some beds Productus is numerous, and also Calci- 

 sphcera. 



The millstone grit is about 900 feet thick in the Bristol coalfield, and is a 

 hard, slightly pink-coloured quartzite. In the Forest of Dean it is about 270 feet, 

 and is a loose yellow red and mottled sandstone made up of well-rounded grains 

 of quartz. The lowest beds are argillaceous and contain remains of Lepidodeiidra. 



5. On the Tyilierington and Thornhun/ Section. 

 By the Rev. H. H. WiNWOOD, F.G.S. 



The author gave a short description of the section between Tytherington and 

 Thorubury which members of the Association had an opportunity of visiting on the 

 Saturday excursion. Beginning at Mr. Hardwicke's quarry, close to the Tythering- 

 ton Station, the Carboniferous Limestone is seen rising sharply from the Gloucester- 

 shire Coal-field, followed by the whole series of beds of this formation, Upper, Middle, 

 and Lower in descending order, until the Old Red Sandstone and Conglomerate 

 appear at the Thornbury end. The chief points to be noticed in the Section are : 

 ( 1) the ' Firestone ' beds to be seen near the top of the quarry, dense siliceous beds 

 m.arking the gradual coming in of the Millstone Grit. (2) The reversed fault 

 bringing the fine-grained yellow beds of the Dolomitic Conglomerate similar to the 



