58 ^ REPORT — 1875. 



all the zones in actual superposition may be examined in certain sections iu tlie 

 Cotteswold Hills, as at Lecldiampton and Cleeve. 



The Fuller's Earth must be studied at North Stoke andLausdown, and the Great 

 Oolite at Coombedown, Lansdown, and other localities around Bath ; the typical 

 Bradford clay, with Apiocrinital heads and stems and beautiful Brachiopoda, near 

 Bradford ; the Forest Marble and Corubrash at Faulkland, Chickwell, Marston 

 Bagot, and Oloford. The Middle Jm-assic rocks are admirably exposed near Calue, 

 and the Upper Jurassic near Swindon, Wilts. 



The gi-eat importance of the Bristol district as a source of mineral wealth, added to 

 the complicated sti-uctm-e of this reo-ion, led my old friendMr. William SanderSjF.Ii.S., 

 to construct an elaborate geological map of the Gloucestershire and Somersetshire 

 Coal-fields and adjacent counti-y, on the scale of foiu- inches to a mile. The topo- 

 graphical portion of this undertaking was reduced to one scale fi-om the Tithe-Com- 

 missionMaps ; and Mr. Sanders traced out all the geological boimdary lines in the field, 

 and laid them down in MS. copies of the Tithe Maps, making copious notes of the 

 strata as he proceeded with his work. The whole was finally reduced to one scale 

 foiu- times the size of the Ordnance-Survey Maps, and reproduced with the most 

 scrupulous care by Mr. Stratton, who for many years assisted Mr. Sanders with the 

 work which he had made the chief object and occupation of his later years ; and it is 

 but simple justice to say that, single-handed, no such exact map for any one area 

 was ever before constructed, either as regards scale or details. This undertaking 

 occupied its author 15 yeai-s, fills 19 separate folio maps, and is a most valuable 

 acquisition to the estate-agent, mineral engineer, and practical geologist. Its real 

 merits can only be fidly appreciated by those who understand how much patient 

 laboiu-, long-sustained energy, and high mental qualities were required to complete 

 80 extended a siu-vey over such a complicated piece of country. In doing this, how- 

 ever, Mr. Sanders has made his scientific reputation, enriched his native city, and 

 achieved a success which falls to the lot of tew men. Having considered the sti-a- 

 tigraphical relation of the rocks in the Bristol district, I desire now to say a few words 

 on a branch of the subject which falls more immediately within the range of my 

 own special stiidies, I mean the organic remains found imbedded in these strata. 

 The science of Palaeontology forms an immense field of observation, and one that 

 widens more and more every year. It is impossible to enter upon any of its details 

 now ; but some of its principles may be satisfactorily explained, and this I shall 

 endeavour to do. 



It is now established, 1st, that the stratified rocks containing organic remains 

 admit of a division into four great groups, representing four gi-eat periods of time : — 

 a, the Palseozoic or Ancient ; b, the Mesozoic or Middle ; c, the Oaiuozoic or Ter- 

 tiary ; and d, the Quaternary or Modern periods. 2ud. That each period is distin- 

 guished by its own hieroglyphic characters, which ai'e engTaven on the rocks in 

 definite and determinable characters. 3rd. That these hieroglyphics are the fossil 

 remains or imprints of animals that lived in the water in which the sediments were 

 formed in successive layers on the earth's crust, and are only found in the rocks 

 they distinguish ; so that it is possible to determine the age and position of the strata 

 from which they have been collected, or, in other words, identify strata hij orijamc 

 remains; and by this key are we enabled to read the pages of the Rock-book, study 

 the history of extinct forms of life, and determine their distribution in time and 

 space. 



Let us apply these principles to the subject we have in hand. The Palseozoic 

 period comprises the history of the Cambro-Silurian, Devonian, Carboniferous, and 

 Permian ages ; and if we attentively examine the fossils of this period contained in 

 the cases of the magnificent Geological Museum of this institution, we shall see that 

 all the organisms belonging to one age are entirely distinct from those belonging to 

 the others. You will find, for example, in the case of the Silurian age, some beau- 

 tiful corals, crinoids, and cephalopods, with a remarkable assemblage of Crus- 

 tacea, the representatives of an extinct family, the Trilobitidse, which are so highly 

 characteristic of chis age that the rocks may be called Trilobitic. 



The Devonian age succeeds the Silurian ; and among the corals and shells so well 

 seen in this Collection we observe a striking resemblance to those of the Silurian on 

 the one side and the Carboniferous Limestone on the other; but when closely ex- 



