356 Mr. Weaver on Floetz Formations. [Nov. 



clove-brown colour, and foliated granular texture, the cement 

 of which is a yellowish-grey, coarse sandy marl. In other quar- 

 ters, the grains of roestone sometimes consist of brown ironstone, 

 e. g. near Eisleben.* 



the compact roestone is frequently marked with beautiful 

 dendritic delineations. 



The roestone usually occurs in beds of 4, 8, and 12 inches in 

 thickness, which alternate with sandstone (particularly calca- 

 reous sandstone), slaty sandstone, and variegated slaty clay ; it 

 lies much more rarely between beds of red clay. Clav galls are 

 also common in it. 



Membranous malachite has been found in the roestone 

 between Emselohe and Blankenheim ; and in calcareous sand- 

 stone, near Sangerhausen. Traces of copper occur likewise in 

 the variegated sandstone of the forest of Thuringia.+ 



It has been remarked by M, Voigt, that the roestone occurs 

 seldom, if ever, in the new red sandstone, when the shell lime- 

 stone formation is found to predominate in the same tract.!' 



Slaty Sandstone. — This is in a great measure confined to those 

 quarters in which thin beds of argillaceous sandstone, or of roe- 

 stone, alternate with slaty clay, and it never appears in anv great 

 thickness. It is usually very micaceous, and of a tender consist- 

 ence, passing into micaceous slaty clay, or into sandstone. 



Incidental Members. 



Limestone and Marl. — These substances are sometimes found 

 in the new red sandstone formation, unconnected with roestone, 

 commonly appearing in an isolated manner in the clay, in the 

 vicinity of the upper 2,-ypsum. Of the limestone, several varie- 

 ties occur, e. g. fine splintery and siliceous, sandy and tender, 

 solid and minute granular, and compact. Of the marl : sandy, 

 rough, and porous, with nodules of sandy limestone ; or as slaty 

 clay marl, with round portions of calcareous spar. 



Loose Sand and Conglomerate. — Beds of these have been sunk 

 through in several parts of the county of Mansfeld, and at first, 

 it was doubted whether they might, not be alluvial. But more 

 extended observation has proved that they belong to the general 

 series. The conglomerate commonly consists of red clay mixed 

 with much sand, including more or less numerous pebbles and 



* Hence we have seen that in the turn red sandstone formation, the oolitic structure has 

 appeared in compact limestone, in foliated granular limestone, in sparry iron ore, and in 

 brown ironstone; and tn the subjacent or lo-wer limestone formation, in swinestone, and 

 rauhwacke. 



The oolitic structure is known also to exist in the carboniferous or first floetz lime- 

 stone ; e. g. in the environs of Tortworth and Bristol ; but it is in the upper portions of 

 the shell limestone that it becomes predominant. 



t Ores of copper and lead, and earthy black and brown cobalt ore, are found in the 

 new red sandstone of England, at Alderly Edge, in Cheshire. 



J This observation appears to hold good in England, where I am not aware that the 

 roestone has ever been met with in the new red sandstone formation. 



