TRANSACTIONS OF THE SECTIONS. 57 



The Lia3 Formation is well developed around Bristol ; aud many interesting and 

 instructive sections of the Lower beds may be studied at Ilorfield, Keynsham, Salt- 

 ford, aud Weston, whilst the Middle and Upper divisions are exposed in other 

 localities. It has been often repeated of late years that the geological record is 

 imperfect, and that many of the leaves, and even whole chapters of the Rock-book 

 on which the hieroglyphics of its history were wi'itten, are wanting ; yet " Time 

 which antiquates antiquities, and hath an art to make dust of all things, hath yet 

 spared these minor monuments ;" for it is certainly true that the Jurassic formations 

 contain a marvellously complete record of the succession of life in time during their 

 deposition from the dawn of the Lias imtil the close of the Ooral Sea, amid whose 

 islands fossil Cycadea luxuriantly flourished, and whose remains are buried in their 

 native Dirt-beds in the Portland Oolites. 



I have shown elsewhere that the three divisions of the Great Lias formations 

 admit of several subdivisions or zones of life, each characterized by a group of species 

 which individualize it. A careful examination of these subdivisions has further 

 proved that there is no confusion in the rocks when carefully examined — that Nature 

 IS always true to herself, although all geologists are not true to Nature. The 

 fossils of the Lower Lias are quite distinct from those of the Middle Lias, and 

 both specifically different from those of the Upper. 



The Ammonites are important leading Liassic shells, that appear to have had a 

 limited life in time, but a wide extension in space ; and they have greatly aided us 

 in determining periods and making out the history of the Liassic Sea. The great 

 Saubopterygia, represented by the Plesiosaunis, and the Ichtiiyopterygia by 

 the Ichthyosaurus, are remarkable forms of Reptilia adapted to the waters of that 

 epoch, whilst the Dinosa.uria, represented by Scelidosaunts, the Pterosaukia 

 by the Pterodnctylus, lived in this area during the Lias age : magnificent spe- 

 cimens of these different forms of reptile life adorn the walls of the Bristol 

 Museum. 



The Jurassic Age. — Dundry Hill, 700 feet in altitude, is the most westerly out- 

 lier of the Oolitic range, from which it is nine miles distant. It is a locality of great 

 interest to the local naturalist, as it affords capital lessons of stratigraphical geo- 

 logy, admirable examples of sm-face-rock sculptiu-e by denudation, and a command- 

 ing point of view for siirveying the same, and showing the grand panorama in the 

 midst of which it stands. * The greater portion of the Hill is composed of Lower 

 Lias strata, which are well exposed at Bedminster Down, Whitchurch, Keynsham, 

 Queen Charlton, Norton, Malreward, Winford, and Barrow. The beds consist of 

 alternations of limestones and shales, having a total thickness of 550 feet. The 

 Middle Lias and Marlstone are feebly developed, and the Upper Lias repre- 

 sented by some thin clays, with dwarfed specimens of Ammonites hifrons and A. 

 communis ; and the Upper Lias Sands, from 1 to 2 feet thick, are not fossiliferous. 

 On these rest beds of Inferior Oolite rock which have long yielded a very fine series 

 of organic remains, some of the best of which are now preserved in the Museum 

 collection. The Inferior Oolite of the south of England admits of a subdivision into 

 thi-ee zones of life : the Loiver, resting upon the Lias Sands, has the Ammonites Mur- 

 chisonce as its leading fossil ; the Middle contains a large assemblage of Mollusca, 

 and especially of Am^nonites, among which Ammo7iites Humphriesianus, So^ccrhyi, 

 concavus, and Blagdeni are conspicuously characteristic ; the Upper contains Am- 

 monites Parkinsoni, Martinsii, and subradiatus, with many Echinoderms and a large 

 series of reef-building corals. These three subdivisions are rarely all developed in 

 the same section ; but the order of then- sequence in uatm-e is as stated in Dundi-y. 

 The lower beds are feebly represented ; and there is an immense development of the 

 middle and upper divisions. 



In the iron shot shelly beds there is a fine assemblage of Lamellibranchs ; and the 

 stratum which covers then is very rich in Ammonites, many with their shells pre- 

 served, and having their oral lobes and other appendages in situ. 



These are succeeded by other conchiferous strata ; and the whole is covered by 

 Ragstone and Building-stone, forming the upper zone, with Ammonites Parkinsoni, 

 Ecliinida, and Corals. Tlie stratigraphical, lithological, and palreoutological 

 conditions seen in the Oolitic capping ot Dundry Hill are repeated in other locali- 

 ties in Gloucestershire, Somersetshire, and Dorsetshire : and a full development of 



1R7o. ^> 



