UPPER EOCEKE (BARTON AND UPPER BAGSHOT FORMATIONS). 595 



We would also call attention to the singular interruption to the 

 bedding which occurs a little west of Long Mead End, where the 

 Leaf-bed and Crocodile-bed are cut through, and replaced by a con- 

 fused mass of clay and sand with drift-wood, a large piece of which 

 is seen to have been anchored vertically in the mud (fig. 3). 



Pig. 3. — Section at Hor dwell (just west of Long Mead End). 



a. Gravel ; h. Green clay with iron. 



This section of an old channel occurs a little west of Long Mead End, and is 

 about 200 yards in length. The green clajs thin out, but the Crocodile- 

 beds are dovetailed into the lignitic sands and clays. All zones are lost, and 

 the whole cliff looks like black or dark ash-coloured sand. It is very shaly, 

 full of wood for the higher 16 feet, and becomes more sandy towards the 

 base. A band of white concretionary clay-stone, with pieces of wood im- 

 bedded in white plastic clay occurs, 16" thick. The sands are rather false- 

 bedded and twisted, but seldom dip more than 10°, and the whole is very full 

 of wood, especially towards the base. At A, the mass of wood is vertical, 

 and gives the appearance of vertical bedding at that spot. The green clay 

 is also penetrated by wood in the same direction. A good many ligneous 

 fruits are to be found near the two extremities after rain. 



This is obviously the channel of an old river, similar to the 

 estuary channel, filled with oysters, which cuts through the " Yenus 

 bed," between Colwell and Totland Bays, and such can frequently 

 be traced in estuaries and fluviatile beds when these are of any 

 extent*. 



Note eccjplanatory of Section through the Lower Headon at Hord- 

 ivell (fig. 4). — The section from the top as far down as the Chara- 

 bed was made nearly due south of Hordwell House. The rest, to the 

 Lignite at the base, was measured about 450 feet east of Long 

 Mead End. At that point the 10 feet or so of beds visible above 

 the Chara-zone, and immediately under the gravel, are considerably 



*■ Mud-beds, teeming with molluscous life, such as those of the Headons, 

 could only be formed on the banks of a tidal river or estuary with extensive 

 flats subject to overflow. Any change of level, whether by modifying the depth 

 of water, making it more or less salt, or altering the quality of sediment de- 

 posited, might profoundly modify the fauna ; and a section through such an 

 area might disclose many minor, but constant, parallel zones of sediment, 

 differing from each other and characterized by quite peculiar forms of life. So 

 long as the section coincides with the direction of the flow of the estuary, 

 the beds are continuous for long distances, but when it becomes transverse we 

 find a channel of confused bedding, with a recurrence of the regular bedding 

 on each side. 



