16 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



A striking example of the relatively rapid elevation of a 

 shore-line is furnished by the East Anglian Crag deposits 

 (Pliocene). The Coralline Crag is indicative of deeper-water 

 conditions than those of the overlying Red Crag. The Red 

 Crag consists of shelly sands, obviously drifted into position 

 in shallow bays which may have been partly land-locked. 

 Judged by the fauna, the oldest Red Crag occurs around 

 Wafton-on-the-Naze in Essex, and the deposits become succes- 

 sively newer as we travel northwards into the area of the 

 Norwich Crag. Mr. F. W. Harmer* has divided the Red and 

 Norwich Crags into a series of zones. Whether the term 

 " zone " can be justifiably applied to the divisions is a matter 

 of no import, for there are certainly different faunal horizons. 

 But the Red and Norwich Crag zones succeed one another 

 northwards, and never overlie one another. In short, the 

 elevation was sufficiently rapid to give rise to the conditions 

 indicated in Fig. 2. It was pointed out on p. 10 that an 

 accompanying phenomenon of rapid upheaval was penecontem- 

 poraneous erosion of the older and elevated members of the 

 sedimentary series. The Crags provide an example of this, 

 for broken and water-worn shells from the older Red Crag 

 deposits occur in the newer zones. t 



Environment. — It is well-known that the fossil remains 

 found in sediments vary considerably in abundance and in 

 character, probably as a result of the influence of the environ- 

 ment upon the organisms. So far as we know at present, the 

 evidence of environment retained in clastic rocks is generally 

 as detailed in the following paragraphs. Deductions regarding 

 the environments of ancient times depend upon the fundamental 

 principle of geology already enunciated, namely, that the 

 present is the key to the past 4 That we are only in the early 



* Quart. Journ. Geol. Soc, Vol. 56 (1900), p. 705. 



t P. G. H. Boswell. Proc. Geol. Assoc, Vol. 24 (1913), p. 330. 



% For a comparison of ancient climates and past conditions of sedi- 

 mentation with those of the present day see Professor W. W. Watts, Pres. 

 Address Geol. Soc, Vol. 67 (1911). 



