1880.] Headon Hill and Colwell Bay, Isle of Wight. 61 



relation of the Brockenhurst with the Colwell Bay bed, and they 

 proceed to show that the marine Colwell bed is — as has been 

 universally admitted for the last 25 years — identical with the 

 marine (Middle Headon) bed of Headon Hill, Avhereas Prof. Judd 

 seems to have separated them by 105 feet of hypothetical strata. 



In establishing this point, attention is paid to the correlation 

 of the various Lymnsea limestones which occur in the freshwater 

 Headon series, a point of some confusion among previous writers. 

 It is shown that the thick limestone in the Upper Headon of 

 Headon Hill is at a considerably higher stratigraphical level than 

 the limestone which forms How Ledge — which latter exists at a 

 lower level in Headon Hill being the top bed of the Lower Hea- 

 don. The identification of this limestone would carry with it 

 necessarily the identification of the marine series lying immediately 

 above it. Accordingly a minute comparison is instituted between 

 the beds which constitute the marine Middle Headon at Headon 

 Hill with the marine series at Colwell Bay. As far as the general 

 distribution of fossils in the whole is concerned they are identical, 

 while a few special beds may also be recognized by similar litho- 

 logical character and fossil contents as identical at both localities. 



The Middle Headon is denuded away from the top of the cliffs 

 in the centre of Totland Bay, between Weston and Widdick 

 Chines*, the last place where they are seen in Warden Cliff being 

 close to the flagstaff of the Coast-Guard Station. An examination 

 of the series there shows that they may be identified, bed by bed, 

 with the Middle Headon of Headon Hill, while the beds of Warden 

 Cliff are visibly and absolutely continuous with those of Colwell 

 Bay. 



This has been the accepted view for the last half century as far 

 as the marine series of Colwell Bay is concerned, though it differs 

 widely from that expressed by Prof. Judd. The Middle Headon 

 having been followed through the cliffs, the same method of 

 observation is applied to the freshwater Lower Headon. Those at 

 Widdick Chine display certain beds: e.g. the Unio-bed, five thin 

 Lynnoea and Chara limestones, which are traceable more or less 

 through this portion of the cliff up to Weston Chine, and so join 

 on to the better exposed Warden cliff beds. Thus the continuity 

 of the Lower Headon beds which occupy all the cliff between the 

 two Chines is easily followed, and the beds of Warden Cliff are 

 identified with those of Headon Hill without a shadow of a doubt. 



* The authors arc indebted to the Rev. 0. Fisher, M.A., for the information 

 that he has this autumn discovered the marine Middle Headon in the Totland Bay 

 brickyard which lies a little above and inland of this portion of the cliff, therein 

 proving that the bed was continuous above the top of the cliff, and linking the 

 Warden Cliff exposure to that of Headon Hill. 



