232 NEOZOIC TIME. [CHAP. xi. 



western extremity of the sea or gulf which stretched from 

 the Paris basin into Hampshire (see map, Plate XII.). 



The Headon Beds present us with a section through 

 part of the delta of this river. The alternation of marine, 

 brackish, and freshwater beds, is due, partly, to the pro- 

 cess of subsidence and silting up, partly, perhaps, to change 

 in the course of the river channel, but the northerly and 

 easterly increase of the marine strata (Brockenhurst Beds) 

 and the southerly increase of the freshwater limestones 

 are facts which prove the deepest part of the estuary to 

 have lain to the north-east of the Isle of Wight, and 

 to have trended from south-west to north-east through 

 Hampshire into Wilts or Somerset, in which direction the 

 embouchure of the great river probably lay. 



The muddy flats of this estuary swarmed with Cerithiadce, 

 Cyrenidce, &c., while the pools of the delta were peopled by 

 species of Planorbis, Limncea, Paludina, &c., the dead 

 shells of which were swept down into the lower reaches of 

 the river ; crocodiles, gavials, and turtles abounded in its 

 waters as in those of modern tropical rivers, and its banks 

 seem to have been clothed with a luxuriant vegetation of 

 reeds, ferns, and palms. 



The southern shore of the estuary lay probably at no 

 great distance from the Isle of Wight, and thence the 

 coast must have curved southward to Normandy, possibly 

 receiving the waters of another river from the south-west, 

 and from a direction parallel to that of the English Channel. 

 The southern shore-line of the Anglo-Parisian sea ran some- 

 where along the northern side of the watershed between 

 the Seine and the Loire, while the northern shore must 

 have skirted the southern slope of the Wealden area. 



Similar conditions seem to have prevailed during the 

 formation of the Bembridge Beds, but Mr. Gardner thinks 

 that in these beds we have evidence, not only of a diminu- 

 tion in the volume of the river, accompanied by a general 



