132 
CHILLESFORt) CLAY. 
All the strata above the red sand seem to belong distinctly to 
the same series, and gravel of similar composition occurs through¬ 
out. The absence of Boulder Clay stones, and the abundance of 
the peculiar quartzites so common in the Forest-bed, make the 
gravels very like those of the Forest-bed series at Bacton and 
Weybourn. These pale-coloured close-grained quartzites are 
found throughout the Newer Pliocene beds, but are particularly 
abundant in the estuarine gravels of the Forest-bed. In the 
Glacial Deposits they are replaced by liver-coloured or red 
quartzites of a different character. The clays are apparently of 
fresh-water or flood origin, but I could not obtain a sample suffi¬ 
ciently well preserved for microscopic examination. The wood 
also was much decayed. Within a shoi t distance of the section 
just noted the clay overlaps upon the Eocene beds. 
The first undoubted exposures of Chillesford Clay occur about 
18 miles north-north-enst of Walton, in the district around Chil¬ 
lesford and Butley, where the day forms a wide sheet, resting on 
the Chillesford Crag or on the upper Red Crag. At Chillesford 
the deposit consists of a fine-grained micaceous loam, too pervious 
to preserve fossils well, and often thoroujjhly decalcified. It has 
only yielded cetacean bones and a few casts of Mollusca. For some 
reason that I am unable to explain fossils decay more readily in a 
sandy loam than in a sand. Thus beds of loam in the Crag often 
only contain obscure casts, though the associated sands above and 
below may yield well-preserved shells. Bones (phosphate of lime) 
do not disappear so readily as shells (carbonate of lime). 
The clay is well exposed in the pit at Chillesford brickyard, 
where it reaches a thickness of about 17 feet, the upper part 
being cut off by Boulder Clay. The base and the gradual passage 
downward into the underlying Chillesford Crag can, however, 
be more readily examined in the pit near the Church, where 
Prof. Prestwich describes the deposit as “ grey clay with a few 
shells and fish-vertebraa, passing down into light-coloured clayey 
sand, with patches of perfect but friable shells.”* In the brick¬ 
yard only impressions of shells occur, though cetacean bones are 
not uncommon, and the skeleton of a whale 31 feet long was 
found some years since.f It is unfortunate that the specimen was 
left exposed to the weather and has now entirely decayed. I 
was unable to find any trace of the shells in 1886, but Prof 
Prestwich records Area [?], Cardium groenlandicum, Cyj)rina 
islandica^ Leda myalis, Nucula, tenuis^ Tclliaa la,ta. 
As this is the typical section of the Chillesford Clay, a sample 
was washed and examined, to trace if possible the origin of the 
material. Microscopically it consist of fine clay with a small 
quantity of silt-sand, plates of mica often -g-V diameter, 
and a good deal of limonite. Not a single large grain of sand, 
and no microscopic fossils were seen in the sample examined. 
The sand consists almost entirely of quartz, in small little-worn 
grains half of which are milky and half clear. One or two 
* Quart. Joiirn. Geol. -Soc., vol. xxvii., p. 336. (1871.) 
t Rep. Brit. Assoc., 1868, Trans. Sect., p. 61. 
