LOWER GREEN SAND. 171 
5. Fragments of the abdomen of two s})ecies of 
Astacida‘. 
(). SIIANKLIN, OR LOWER GREEN SAND. 
Silicioiis sands and sandstone of various shades 
of green, grey, red, brown, yellow, ferruginous, and 
white, with subordinate beds of chert, limestone, and 
fuller’s earth, constitute the group of deposits to 
which the name of Slumklin-s'and formation’ is 
now appro})i’iated. These beds are but obscurely 
seen in the east of Sussex, but as we proceed to- 
wards the west they gradually rise into hills of con- 
siderable altitude, and form a striking feature in the 
})hysical geography of the country. They admit 
of a tri])le division, as was first shown by Dr. Fitton 
in his admirable memoir on the beds below the 
chalk.* 
“ The first or uppermost consists of sand, with 
irregular concretions of limestone and chert, some- 
times disposed in courses oblique to the general 
direction of the strata. The top of this sand in the 
vicinity of Folkstone and Hythe forms an extensive 
plateau, resembling that of the Blackdown range of 
lulls in Devonshire. 
“ The second consists chiefly of sand, but in some 
})laces is so mixed with clay, or with oxide of iron, 
as to retain water ; it is remarkable for the great 
variation in its colour and consistency. 
“ The third and lowest group abounds much 
more iu stone ; the concretional beds being closer 
together and more nearly continuous.” 
* Ai. nals of l’hilosoph\ , 1827. 
