Geology of England and Wales,** i^c 217 



" The (jlreen Sand consists of loose sand and sandstone;" 

 the ceinent to the latter being calcareous. It contains par- 

 ticles of a green substance, probably green earth:* and hence 

 its name. Subordinate beds and masses of chert and lime- 

 stone, with veins of chalcedony, fuller's earth, sulphate of 

 barytes, quartz, &c., occur in it, with numerous petrifac- 

 tions. Among these are echini, alcyonia, some unknown 

 genera, and various testacea : a single quarry furnishing 

 150 species. 



The Weald Clay has not been thoroughly explored : 

 but it consists of a dark tenacious clay, and a blue, or 

 grey, calcareous marie, often hard enough to admit a pol- 

 ish. It has been suspected, that it is a fresh water depos- 

 ite; but the question is by no means settled, as its organic 

 remains have never been described. 



Iron sand " is composed of a series of strata, in which 

 sand and sandstone prevail, occasionally alternating with 

 subordinate beds of clay, loam, marie, fuller's earth, and 

 ochre." These strata contain brown oxide of iron, in con- 

 siderable proportion, so as sometimes to be w^rought as an 

 ore. "The texture of the sandstones is evidently mechan- 

 ical, and they often, indeed, form coarse grained conglome- 

 rates." Ferns, charred wood, and even a kind of cannel 

 coal, occur in these sandstones. Their organic remains 

 have yet received but little attention : but they are probably 

 sparingly dispersed. 



We have no means of determining whether any members 

 of this series of rocks exist in this country. 



Oolitic series, — This is an important series in an econom- 

 ical view, as it furnishes the best architectural materials in 

 England. It consists " of a series of oolitic limestones, of 

 calcareo-siliceous sands and sandstones, and of argillaceous 

 and argillo-calcareous beds, alternating together, and gene- 

 rally repeated in the same order ; i. e. a formation con- 

 sisting of many beds of oolitic limestone, resting upon one 

 of calcareo-siliceous sand, and that again upon an argillo- 

 calcareous formation." The whole series is divided into 

 the Upper, Middle, and Lower Oolitic System ; and these 

 are subdivided. 



*This has been ascertained by Berthier to be a hydrate of iron, and not an 

 earthy chlorite. It accompanies the lower chalk beds throughout France, 

 and is found in a marly Limestone, resting on Jura Limestone, at tho Perfe 

 du Rhone See Brongniart sur la craie. (Ed.) 



Vol. VII. No. 2. 28 



