British Association. 467 



* " The small part of this island, occupied by the crag formation, 

 is intersected in one spot with several estuaries, which have com- 

 pletely removed this generally superficial fossiliferous stratum, the 

 bed of the estuary being formed in an older formation. Along the 

 banks of the Deben, which flows through a part of the coralline 

 crag, in some spots the fossil shells line the shore in gi-eater numbers 

 than the recent testacea; and, during the period in which this 

 estuary has been formed, prodigious numbers of these fossils must 

 have been swept down into the German Ocean, and there indis- 

 criminately mingled with the reliquice of existing species of MoUusca. 

 It is not merely the extent of surface at present occupied by these 

 estuaries which has thus been denuded of the crag, but considerable 

 tracts of marsh land formerly connected with them, but from which 

 the water has since been shut out, have also lost this original 

 covering. Within a very short distance of the Deben, another 

 estuary, the Stour, flows through a lacustrine deposit belonging to 

 the newer pliocene period ; and here, in addition to the shells, is a 

 considerable stratum of mammalian remains, which, at one period, 

 evidently extended as far as the opposite bank of the river, a distance 

 of about a mile and a half or two miles. 



'■' I must now look forward some few thousand years, and antici- 

 pate the time when, by the recession of the sea, or the elevation of 

 the land, the deposits forming at the mouths of these estuaries has 

 become accessible, and is made the subject of geological investigation. 

 I must also assume, that the geologists of that remote period have 

 followed the same course of induction that has recently been pursued, 

 and have arrived at similiar conclusions respecting the course to be 

 adopted in ascertaining the relative antiquity of tertiary deposits. 

 The age of the formation in question, then, is about to be tested by 

 comparing its organic remains with the then existing species. Of 

 what will these fossils consist, and whence will they originally have 

 been derived ? The bones of such animals as are now drifted down the 

 rivers Deben and Stour will be mingled with those of the extinctMam- 

 malia of the newer pliocene period. The living species of Mollusca 

 now inhabiting the German Ocean, will be found associated with the 

 extinct Testacea of the newer pliocene, older pliocene^ and, perhaps, 

 even miocene epoch. Yet this deposit, in which the organized 

 beings of different geological periods shall be found thus indiscrimi- 

 nately mingled, will be one exhibiting every appearance of regular 

 stratification ; a deposit in which a large portion of Testacea will be 

 found naturally grouped, and, in which, there will be the clearest 

 evidence of their having become entombed on the spot which they had 

 long previously inhabited. That the influences of causes now in 

 operation is resdly producing such an effect as the one now described, 

 admits of almost actual demonstration ; for the fossil shells of the 

 crag are thrown up along various parts of the Suffolk coast, several 

 miles from the spots in which they have been carried down. 



'' It may be said, that these older shells, entering into the new 

 deposits, carry with them evidence of the stratum from which they 



• The portion between inverted commas is given at full length. 



