150 THE PRESIDENT'S ADDRESS. 



diagonally across England, in a north-easterly and south-westerly 



direction, the high ground, composed of Limestone, forming low 



is of hills, with escarpments facing the south-west and overlooking 



tho valleys. The Lower Oolites rest on the Lias, the Middle Oolites 

 on the Oxford Clay, and the Portland or Upper Oolites on the Kim- 

 meridge Clay. 



The Lias formation is well developed around Cheltenham, but not 

 often exposed. Railway cuttings, brick-yard pits, and the marlstone 

 quarries of several localities have yielded a large series of its 

 characteristic fossils in good preservation. The Lias formation stands 

 conspicuous among the Mesozoic Strata in the completeness of its 

 record, for the chapters of its life-history are written in enduring 

 characters on its dark Shales and Limestones, and which can be deci- 

 phered with a certainty that is very remarkable ; in this respect it 

 presents a favourable field for tracing the course of life during the long 

 period of time its strata were slowly accumulating. The Lias, therefore, 

 forms an exception to the general assertion that the Geological record 

 is imperfect, and, as a consequence, the study of its organisms merits 

 a careful study by all who are engaged in attempting to expound 

 theories of the earth. 



It has been often repeated of late years that the Geological record 

 is imperfect, and that many of the leaves, and even some of the 

 chapters of the great Rock-book, on which the hieroglyphics of its 

 history were written, are wanting ; yet " time, which antiquates anti- 

 quities, and hath an art to make dust of all things, hath yet spared 

 these minor monuments," for it is certainly true that the Lias forma- 

 tion contains a marvellously complete record of the succession of life 

 in time during the long period occupied in its accumulation, and 

 which, when critically compared with the fauna of the Triassic Strata 

 which preceded, and the Oolitic Rocks which succeeded it, shows a 

 marvellous marked difference in the reptiles, fishes, cephalopoda, 

 echinoderms, and corals that lived in these two different periods of 

 Mesozoic time. The Lias is divided into Lower, Middle, and Upper, 

 and each division is characterised by a distinctive fauna ; many of 

 the strata abound with eephalopods, whose shells form leading fossils 

 by which these three divisions of time are recognised wherever the 

 Lias formation is exposed. 



The Lower Lias is divisible into seven, the Middle into five, and 

 tho Upper into three zones of life. 



Besid which well identify the strata, each zone 



cont iblage of gastropods and conchifers, special to the 



beds, so that cacli b life becomes a special object of study to 



the Palaeontologist. 



Lower Lias beds are found in the valley, the Middle in the 

 lower slopes of the Cotteswolds, and the upper capping the .Middle 

 Lias, and interposed between it and the Lower Oolites. 



Tho reptiles that appeared in the Lias seas, estuaries, rivers, and 

 land, present us with some of the most marvellous combinations of 



