part 4] JURASSIC CHRO^^OLoar. 457 



cases was that specimens had been redeposited inside lumps of 

 original matrix. Big lumps of derived matrix were in the Watton 

 bed, but there arose the dithculty of reconciling such lumps with a 

 fine-grained laminated deposit — the former indicated violent action,, 

 the latter very tranquil conditions and, possibly, deep water. The 

 tranquil conditions seemed to be inconsistent with the wave-action 

 suggested by Dr. Lang. 



The Author agreed with Mr. Lamplugh that the Watton Bed 

 was a highly condensed deposit : it had taken the whole of the 

 time of the Upper Lias — some thirty h emerge — to deposit 5 feet ; 

 but the question was whether the deposit as seen now represented 

 anything like the original mass laid down. The Author supposed 

 not. How much had been removed by penecontemporaneous erosion 

 without leaving a trace behind ? 



With reference to Mr. Pringle's remarks, the Author wished to 

 acknowledge how greatly he was indebted to his collaborators for 

 their Appendices, representing a mass of new observations suj^ple- 

 menting his paper. The most interesting point, perliaps, was that 

 the S3''stem of many chronological divisions, which the Author 

 might claim to have originated, had been extended b}'' his col- 

 laborators : that testimony to his moderation was welcome ; 

 because his original number of subdivisions had often been con- 

 dem^ned as excessive. He had always been compelled to go on 

 asking for more, and now other investigators went farther stilh 

 This constant lengthening of the Earth's chronology was particu- 

 larly interesting. 



In noting that palaeontological planes did not coincide with 

 lithological planes, Prof. Boswell liad, as he said, drawn atten- 

 tion to the Author's work of many years ago. It was a vindication 

 of the subdivisional method that it had given these results so 

 clearly, and had shown the uselessness of lithology as a guide 

 to date. 



