Peacock: Naturalists at Newark. 119 



seas, it would be impossible for any life to exist, and con- 

 sequently it is very rare indeed that any fossils are found in 

 these marls. What are found generally relate to animals which 

 crawled or walked along- the soft muddy shores of the lakes, 

 and left their trails and footprints to be baked by the sun's heat. 

 I have here the footprint of an animal called the Labyrinthodon, 

 also shales showing- worm and other tracks which were made 

 on these ancient shores. Besides these, you may notice one 

 piece showing- the impressions made by the raindrops of a pass- 

 ing- shower. Just one other thought before we leave this pit. 

 The level of the Dead Sea is nearly a quarter of a mile below 

 the level of the Mediterranean, and its waters are too salt for 

 any life to exist in them. Now I want you to imagine that the 

 barrier separating- these two waters is removed ; the waters and 

 living contents of the Mediterranean would be poured into the 

 Dead Sea and tend to esta.blish a level. But the living- creatures 

 which first came over would be immediately killed by the salt 

 waters of the Dead Sea, and their bones spread over the 

 bottom. These would be buried in the accumulating mud, and, 

 being- preserved in a fossil state, would form what g-eologists 

 term a Bone Bed. Now this is just a picture of what took 

 place at the close of this Keuper period. The barrier between 

 the salt lake and the outside ocean was removed, and Bone Beds 

 were formed. The low escarpments which we see to the east- 

 wards indicate the position of the Rhcetic Beds. These are 

 passage beds formed during the chang-e which took place in the 

 ancient lakes before the waters became suitable for the ordinary 

 marine life to exist and multiply. I have here a section of the 

 Rhcetic Beds at Westbury-on-Severn, where they are most fully 

 developed, and you will see two interesting- Bone Beds marked, 

 each about one inch thick. These beds are in places almost 

 entirely made up of fossil bones, teeth, scales, and coprolites. 

 When the period of change had completely passed away, and 

 the waters had become as ordinary marine water, then we begin 

 to g-et the great clay deposits of the Liassic formation. But we 

 will leave this most interesting formation as being perhaps just 

 a little beyond the present local geology. 



After Mr. J. Shipman, F.G.S., had added ;i lew weighty and 

 incisive words to drive home important points, various diagrams 

 and specimens of fossil footprints, worm tracks, pseudomorph 

 crystals of rock salt, etc., obtained from the new red sandstones, 

 were exhibited in illustration of the remarks which had been 

 made on the past history of these rocks. The part) afterwards 



ickx> April 3. 



