STRATA OF SHROPSHIRE AND DENBIGHSHIRE. 13 



The clays interstratified with these coals are full of the rootlets of 

 Stigmaria Jlcoides ; and the overlying shale, which is four or five yards 

 thick, is charged with tiigillarice, Catamites, and Lepidodendra, of 

 several species, Pecojiteris (BucMandi ?), Neuropteris cordata, Aste- 

 rophyllites, Araucarites, Dadoxylon, Sternbergia, and other plant- 

 remains, the grouping being similar to that of the lower seam just 

 described. 



Above this shale we reach a rock which is known in the district 

 as the Coedyrallt rock, a good section of which may be obtained in 

 the Coedyrallt wood on the right bank of the Dee, a little below the 

 junction of the Ceiriog with that river. It is also worked in quarries 

 along its outcrop on the right bank of the valley of the Morlas. 

 North of the Dee it is quarried in Wynnstay Park, as well as near a 

 farm-house one mile to the N.E. of Ruabon. 



It consists of buff, yellow, and greenish grey sandstones, in which 

 obscure traces of organic remains are found. These sandstones en- 

 close large irregular masses of limestone, which are not drifted frag- 

 ments, but which form integral parts of the rock. 



The limestone is usually grey in colour and of a coarse crystalline 

 texture. Some idea of the quantity of calcareous matter contained in 

 this rock may be formed from the fact that below Escob Mill, on the 

 right bank of the brook Morlas, a deposit of calcareous tufa of con- 

 siderable extent and thickness has been formed by water percolating 

 through it. 



The rock also contains in its upper portion a bed six feet thick, of 

 calcareous nodules and concretions set in a clayej' matrix. Above the 

 Coedyrallt rock, which varies in thickness from 40 to 80 feet, is a bed 

 of red marl ; shales follow until, at a height 210 feet above the Morlas- 

 main coal, we reach a double coal-seam with a parting of fine fire- 

 clay, as follows : — 



ft. in. 



Coal • 1 6 



Fire-clay 10 



Coal 1 6 



This coal has been worked a little in the " NewFlannog Pit." It 

 is succeeded by 45 feet of blue and dark grey shales, which are 

 capped by a rock which, in the New Flannog pit, was about 6 feet 

 thick. 



This rock cannot, I think, be far from the base of the dark red 

 sandstones, group 4 of Section 11 ; but the exact distance is not at 

 present ascertained. 



Good sections of these upper sandstones may be seen along the 

 left bank of the Dee from near the new bridge recently erected on 

 the Penyllan estate to Erbistock ferry. Fragmentary sections are 

 also seen in the brooks about Pant Mill. Near their base these beds 

 are of a marly nature ; but they become massive sandstones as we 

 ascend. Towards their middle portion there are occasional irregular 

 beds of small pebbles. There is much false-bedding among the sand- 

 stones, which also vary in colour from brown to grey ; they also con- 

 tain white gypsiferous bands. 



