RED CRAG. 
83 
would be taken of the Red Crag at Walton, for it is thin, of small 
extent, and a large portion of it is decalcified, S. V. Wood, 
jun.,^ and Prof. Prestwichf both give diagrammatic sections of- 
Walton Cliff, in which the marked tendency of the different 
Pliocene strata to overlap on. to the London Clay is distinctly 
shown. Mr. Whitaker, who has recently studied the deposits, 
notes the following section made up from observations taken at 
many points. { 
Cliff-section at the Naze, 1871. 
Clayey soil. 
Fine gravel up to 7 feet or more. 
Chillesford Beds ? Light-coloured (grey and brownish), more or less 
bedded sandy clay, loam, and clayey sand; here and there with flints, 
flint pebbles, and quartz-pebbles, and sometimes a little sand; often with 
a layer of pale purplish clayey sand, sometimes a thin peaty laj^er (in 
places with well-preserved wood), and sometimes pebbles and flints at the 
bottom. Up to 7 feet. 
Brown and bulf sand, false-bedded; sometimes with many 
small quartz-pebbles, and some small phosphatic nodules: 5 
or 6 feet, but not constant, and sometimes passing into the 
bed below. 
Brown and grey sand with shells and ferruginous nodules, 
false-bedded; sometimes with thin layers of hardened clay 
and, in the upper part, many small black phosphatic nodules 
and small quartz-pebbles. 
Thin bed of phosphatic nodules and phosphatized bones at the 
bottom in places. 
London Clay, brown at top, but soon getting grey. 
When re-examined in 1886, the northern part of the section 
showed little-altered shelly Crag, consisting in places of light- 
coloured, sometimes almost white, shell-sand with scattered whole 
shells. Except Pholas imbedded in cement-stone, no shells with 
the valves united were met with, and the great majority of the 
mollusca were broken and water-worn. At a distance the Crag 
appears to be fairly evenly bedded, with alternating bands of 
reddish and buff sand. But this bedding proves to be deceptive, 
when examined more closely, for the ferruginous lines merely run 
parallel with the clays above and below the Crag, the greater 
part of the Crag being strongly false-bedded, though perhaps not 
at such high angles as in most other sections. Oxidation here 
produces a result the exact converse of that ordinarily met with. 
At Walton false-bedded sands seem to be evenly-bedded, but 
more generally oxidation of the beds tends to give a deceptive 
appearance of current-bedding. 
It has already been observed that the principal interest of the 
Walton Crag lies in the close resemblance of its fauna to that of 
the Coralline Crag. At Walton, according to S. V. Wood, the 
fauna is also nearly free from the mixture of derived specimens 
from other deposits, such as occur so abundantly at nearly every 
* Quart. Journ. Geol. Soc., vol. xxii., p. 548 (1866) ; and Supplement to the 
Crag Mollusca. Introduction. Pal, Soc. (1872). [Section xxi.] 
f Ibid., vol. xxvii. p. 333. (1871.) 
t Geology of the eastern end of Essex. t^Memoirs Geol. Survey), p. 13. (1877.) 
Red ' 
Crag 
