TRANSACTIONS OF THE SECTIONS. 49 



to the fact, A description of the Geology of Tortworth was made by Mr. Weaver* 

 and by Buckland and Conybearef. These memoirs were written at a time when 

 the correlations of the then so-called Transition rocks were not understood ; there- 

 fore they help us little toward a correct imderstanding of their age and character. 

 It was not imtil Murchison had succeeded in making out the true relation and 

 character of the upper fossiliferous beds beneath the Old Red Sandstone, and had 

 arranged his groups by their organic remains in consecutive order under the name 

 of the Silurian System, that the true age and relation of the Transition strata of 

 Tortworth were understood. It then appeared that the Silurian rocks of Tort- 

 worth are the southern extension of the same formations which, extendino- through 

 Micklewood Chase and the Vale of Berkeley, appear as a dome of Upper Silurian, 

 rising near Tites Point on the left bank of the Severn near Purton Passage. The 

 same rocks are foimd wrapping round the base of May Hill and Huntley Hill in the 

 Forest of Dean, in the Valley of Woolhope, Herefordshire, on the western slopes 

 of the Malvern Hills, and extending through Eastnor and Ledbury to Wenlock 

 Edge, Salop. Whatever, therefore, is true relating to the Palfeontological cha- 

 racter of the Upper Silurians in these other localities, is equally correct of the 

 same formations that lie in the miniature basin of Tortworth. The Caradoc Sand- 

 stone, or, as it is now called, the Upper Llandovery Sandstone, is the oldest rock at 

 Tortworth, and forms the dominant stratum of the district. It covers an extensive 

 area ; and some small sections are seen at the south side of Micklewood Chase, and 

 on both banks of the Avon near Damory Mill. Lithologically and palreontologically 

 it is indistinguishable from hand specimens of the same formation at May HHl. It 

 abounds in fossils : Pentamerus, Strophotnena, Orthis, Atrypa, Spirt/era, andZeptcma, 

 with broken Trilobites belonging to the genera Trimicleus, Cahjmene, Illeenus, and 

 Phacops, are found, together with the stems of Crinoids and Tentaculites. 



The Wenlock Limestone is exposed at Falfield Mill and Whitfield and other 

 places ; from its various beds the characteristic Upper Silurian Corals are collected, 

 as Favosites, Syringopora, Halysites, Porites, Caryophyllia, and Acervularia. 

 Crinoidal stems are veiy abundant. Many Brachiopoda (as Leptmia, Atrypa, 

 Orthis orbicularis) and Gasteropoda (as Euomphalus discors and Euomphalus fimattis) 

 are collected, with fragments of Calymene BliimenbacMi and Phacops caudatus. 

 The Ludlow Rock is best exposed at low- water mark on the west bank of the Severn 

 at Purton Passage, where it rises in a dome-shaped mass, and dips away beneath 

 the beds of Old Iled_ Sandstone of the Devonian series on the opposite shore ; the 

 upper portion of this formation consists of greenish-grey micaceous beds, with 

 Leptana lata, Orthis unguis, and Terebratula Wilsoni, which probably represent the 

 Aymestry limestone. 



Devonian. — The Old Red Sandstone, in its upper parts, consists of fine-grained 

 thin flagstones of a whitish-grey colour ; and Tortworth Court is built of these fine 

 building beds. This upper division is underlain by coarse quartzose conglomerates 

 and at the base by red sandstone, which rests on the Llandoveiy strata. The same 

 succession of beds is very persistent, with conglomerate in the centre and lower 

 third, and sandstone above and at the base. 



Carbmuferous. — The Bone-bed at the base of this formation is well developed 

 together with the Lower Limestone Shales. Psammodus linearis, P. lavissimus 

 Coprolites, and Pileopsis angustus, Phil., a shell of the Carboniferous Limestone, arfe 

 the leading fossils here. 



Millstojie Grit and Coal Measures.— These beds have been fully and accurately 

 described in the ' Geological Transactions,' by Weaver, Buckland, and Conybeare 

 accompanied by many valuable sections. They consist of Millstone Grit Lower 

 Coal Measures, Pennant Sandstone, and Upper Coal Measures ; the whole series 

 may be studied and examined in this district. A section constructed from Tort- 

 worth Green to Frampton Cotterell gives the following :— Tortworth Green Old 

 Red ; the Court and Park, Lower Limestone Shales ; Ley Hill and Cromhall 'Car- 

 boniferous Limestone ; Cromhall Heath, Millstone Grit ; Sweethouse, Lower Coal- 

 Shales ; Sweethouse to Robin's-wood House, Pennant, and from Robin's-wood 

 house to Frampton Cotterell, Upper Coal Measures of the Coal-pit Heath basin. 



* Trans. Geo]. Soc. vol. i. p. 317 (2nd »erie8). + md n 210 



1875. 5^- • 



