94 DEPOSITS OF PHOSPHATE OF LIME. [bull. 46. 
is a highly siliceous sand, containing no phosphate, except where the 
nodules have been decomposed. The siliceous pebbles of these lower 
beds are of very general distribution. They are found all along the 
Lower Greensand outcrop in England at Upware, Sutton, Brickbill, 
Farrington, and other places, also in the Neocoinian strata at Schop- 
penstedt, in Brunswick. Many of these pebbles are fossiliferous. 
Mr. Keeping 1 found in some chert pebbles many shells and crinoids 
of the Carboniferous age. In others he found many Jurassic shells 
and echinoderms. He thinks most of the pebbles were derived from 
an ancient barrier axis, which, in the Lower Neocomian period, sepa- 
rated the north from the south Neocomian seas in Europe, but " which 
was in the time of the deposition of the iron sand series suffering rapid 
denudation and destruction." 
The Lower Greensand phosphate beds have numerous outcrops in 
Surrey, Sussex, and Kent. They are, however, thought by W. Keeping 
not to be of the same age as the beds of Cambridge and Bedford, but 
to belong to the Sand gate and Hythe series. 
Tertiary phosphate beds. — The Tertiary phosphate deposits occur in 
or directly under the various Crag formations of Norfolk, Suffolk, and 
Essex, but are richest and most extensive in the county of Suffolk. 
The Crag of Suffolk and Norfolk runs along the coast from about 5 
miles northwest of Kromer, in Norfolk, for a distance of 70 to 80 miles 
to Hardwick, in the northern part of Essex. This belt is from 7 to 22 
miles wide, being widest in the neighborhood of Norwich and narrowest 
at Halesworth, in Suffolk. Beyond these limits the Crag often occurs 
in patches in the county of Essex. The Suffolk and Norfolk Crag does 
not extend all over the above mentioned area, but in many places it is 
covered by alluvium, and in others, especially in Essex and in the south 
of Suffolk, it has been removed by erosion, and the London clay crops 
out. 
It is in the county of Suffolk, and especially in the district between 
the rivers Orwell, Deben, and Aide, and in the country surrounding 
the central mass of Coralline Crag at Sutton, that the Tertiary phos- 
phate beds have been most successfully and profitably worked. The 
Crag formation of this country is composed largely of the Coralline and 
Bed Crags. These formations are each separable into two divisions. 
Prof. J. Prestwich 2 has divided the Coralline Crag into the upper part, 
consisting mostly of remains of Bryozoa, and the lower part, consisting 
of light-colored sand with many shells mixed in with it. The two beds 
together are rarely over 20 feet thick, and rest on the London Clay 
(Eocene). The Red Crag consists of irregularly stratified sands stained 
with oxide of iron. It comes above the Coralline Crag, though in most 
1 The Fossils and Palseontological Affinities of the Neocoraian Deposits of Upware 
and Brickhill, 1883. 
Quart. Jour. Geol. Soc. London, vol. 27, 1871. 
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