602 MESSES. GAEDNEE, KEEPIIJG, AND MONCKTON ON THE 



shams, with its giant Nummulites, Bullas, and Cowries, and its- 

 wealth of corals, differs far more from that of the Upper Brackle- 

 sham, than the latter does from that of the Bartons. Had the 

 Barton Series been described from the HighclifP section first, and 

 then been followed from west to east, taking first Alum Bay and then 

 "Whitecliff Bay, the entire Upper Bracklesham Series would have 

 found a place in it, and the base-line been drawn where a decided 

 physical change existed. The accidental circumstance that Mr. 

 Eisher began to plot the Bracklesham Series at Selsey, led him 

 to place their limits very high instead of very low. The whole 

 of the strata on both sides of the Bill down to the London Clay 

 were placed in the Bracklesham, perhaps chiefly because the thick 

 freshwater sands and clays, which cut them in two, are unfossilifer- 

 ous and seldom or never exposed on the shore. The highest beds 

 at Selsey were traced to the I^ew Forest, where still higher beds 

 with similar species overlay them, and, finally, a small zone, con- 

 taining a particular variety of Niimmulites ehgajis, was fixed upon 

 as the upper limit of the Bracklesham Series. That the line is 

 drawn in "passage beds '"' is admitted by Prestwich and by Pisher 

 himself, and it is thus less satisfactory than one coinciding with a 

 physical break. As no better line of separation can be found, how- 

 ever, without trenching very considerably on the Bracklesham, we 

 propose to retain the base-line in the zone of Nummulites elegans,. 

 var. Prestwichiana. In retaining the present divisions of the 

 Bracklesham, we must remember that the lower is very different 

 from the upper, and that the latter passes insensibly into the over- 

 lying Bartons. 



The section at Whitecliff Bay (fig. 8) commences with mottled clay 

 resting on chalk; then follows an eroded surface with scattered 

 pebbles; some loamy sand and the Bitrujm-hed ushering in the 

 London Clay. This is nearly 400 feet thick, and at 50 feet from 

 the top we can recognize layers of soft concretions, crammed with 

 Pectuncidus, representing the Bognor Beds. It is capped with 100 

 feet of buff sand with a few bands of scattered pebbles. The- 

 section is very oblique to the outcrop, so that all these beds have an 

 exaggerated thickness. The Lower Bagshots consist of 137 feet of 

 finely laminated clays and sands with vegetable impressions, and 

 end a little below a bed of Cardita planicosta, marking the base of 

 the Lower Brackleshams. These consist in turn of 56 feet of greenish 

 sandy clay, evidently marine; 52 feet of laminated clays, with 

 some lignite of doubtful origin ; 90 feet of greenish sand, marine ; 37 

 feet of the same with Nummulites Icevigatus ; QQ feet of clay, with belts 

 of lignite and underclay with roots ; and then the Fecten-corneus zone 

 of the Upper Bracklesham. The " Brook Bed " of Fisher follows, 23 

 feet thick, greenish marine sandy clay ; sandstone 5 feet ; Nummu- 

 lites-variolarius zone 34 feet 6 inches ; 93 feet of Huntingbridge 

 Beds, not very well exposed ; terminating with the zone of iV. 

 elegans, var. PrestwicJiiana, taken as the line of junction with the 

 Barton Series. 



The Barton Beds were not separated by Prestwich in 1846, 



