1(5 
Transactions of the Society. 
APPENDIX I. 
The Gault of Folkestone, and its Continental Equivalents, 
Tlie Folkestone cliffs offer one of the best opportunities for a sys- 
tematic study of tlie Gault Microzoa, with respect to the distribution 
at different horizons; chiefly on account of the completeness of the 
exposure of the series at this locality. Indeed, it has already been 
selected as a basis for zonal subdivision by C. E. De Ranee * * * § and F. G. 
H. Price, "f who have rendered this section classic by their researches 
into the palaeontologico-zonal subdivision of the series. 
The section at Folkestone is by no means of the maximum thick- 
ness.J According to the measurements given by Price, it is 99 ft. 4 in., 
measured from the band of sulphide of iron nodules of zone i. — 4 ft. 
above the bed containing Ammonites ( Acanthoceras ) mammillatus — up to 
the base of the Chloritic (glauconitic) Marl.§ 
The Gault section exposed in the Folkestone cliffs is not seen com- 
plete at any one spot, owing to the number of local landslips caused by 
the sliding of the Lower Chalk upon the impervious and wet surface 
of the Gault; the latter being often squeezed out and faulted. By 
careful observation the whole series of Gault strata can be followed, 
from near the Harbour, where it lies upon the Folkestone beds of the 
Lower Greensand (Aptian), under Copt Point to the middle of Eastwear 
Bay. Just south of Martello Tower No. 3 on Copt Point, the top of 
the Gault is well seen, capped by the Chloritic Marl. Here is also 
found the curious bed of Greensand (“ Middle Greensand” of Griffiths), 
which runs through zone xi. at 17 ft. 6 in. from the top, and having a 
thickness of 3 ft. 3 in. below fnis. 
With a cliff-section like this one can take the beds in regular 
sequence, from the base to the top of the series, noting the various 
changes that take place in the lithological structure of each bed, con- 
comitantly with the distribution of the microscopic fossil fauna; and 
this has been attempted in the present work. 
It should be borne in mind that the zones here followed cannot be 
expected to hold good in their details over large areas, and the interest 
attaching to the distribution of the microscopic organisms will be more 
from a local standpoint than in its general bearing on Gault strata. 
The beds forming the section of the Gault at Copt Point and East- 
wear Bay are very variable in lithological character, and they apparently 
constitute an intermediate type compared with the series in other 
localities. 
The Gault formation becomes more arenaceous towards the west, as 
in Dorset and Devon, where it represents a more persistently littoral 
or shore-line deposit; whilst the Gault to the north and east of Folke- 
* Geol. Mag., vol. v. (1868) p. 163. 
t Quart. Journ. Geol. Soc., vol. xxx. (1874). Also ‘ The Gault,’ 1879. 
% The Gault in Kent and Surrey ranges from about 100 to 200 feet in thickness 
but at Caterham it has been proved by a well-boring to be 343 feet thick. See 
Woodward’s Geol. of England and Wales, 1887, p. 383. 
§ Quart. Journ. Geol. Soc., vol. xxx. (1874) p. 343. 
