18 GJSOLOGY OF THE AVON IJASJN. 



iSurv., vol. i.) :i Ktxitiou is p^ivcii of the Dolomitic Conu^Io- 

 morale. A section of the Old Rod Sandstone to the soutli 

 of Battery Point will bo found in the pages of onr own 

 rrocoediugs (vol. ii., No. 8, p. 71)) ; and the occurronco of 

 fisli remains in tliose beds has been noted (Baily, Brit: 

 Assoc, 1864, p. 49, and Froc. B.N.S. loc. cit.). In Iiis 

 second paper On the. Geology of the Bristol Coalfield, Mr. W. 

 W. Stoddart gives a section, reproduced in Fig. 2. Finally, 

 in a little vohime on The Natural History of Portishead, by 

 J. N. Duck, there is a geological map of the district; and 

 a few pages are devoted to a short Jind for the time (1852) 

 conventioniiUy convulsional account of the district and the 

 dislocations to which it has been subject. This socnis to be 

 tho sum of the geological litenituro of tlio locality. 



In our recognised geological maps, that by Mr. William 

 Sanders, and that by tho Geological Survey, thoi'c is much 

 valuable information, with some differences of detail. Such 

 mn.ps, liowovcr, arc, taken by themselves, insufficient to 

 indicate tho varying sti'iko and dip of tho rocks and tho 

 not altogether unimportant problems which suggest them- 

 selves when tho beds are practically examined iti the field. 



I ventui'c therefore in this paper to set down certain 

 observations, and to draw attention to, if I cannot solve, 

 some of tho suggested problems. 



2. — Physical Features and General Geological Structure. 



Portishoad lies at tho north-easterly ond of a well-marked 

 ridge, which I'uns in a south-w(!sterly direction to Clcvod(m. 

 As was clearly pointed out by Ihickland and Conybeare, tho 

 ridge " is divided along its summit, by a longitudinal valley, 

 into two parallel cirests, tho southern consisting of Mountain 

 Limestone, tho northern of Old Rod Sandstone, an inter- 

 mediate valley marking the Shale that divides the i;wo 



