34- Outlines of Geology. 



Nottinghamshire, ami Staffordshire. Without, however, further 

 enumeration of tho situations in which this rock occurs, a glance 

 at the map will show its extent, and we may employ our remaining 

 time by shortly advsi ting to its contents and embowelled treasures. 



The texture of led sandstone, and I had almost said its colour , 

 .are very various; sometimes it is very soft and clayey, but in 

 parts much more lapideous and indurated, and it is associated with 

 beds of a peculiar conglomerate, consisting of nodules of different 

 substances, cemented by marl or sand, and with a rock which we 

 shall afterwards describe under the name of amygdaloid. It is 

 generally unfit for aichitectural purposes, and from its softness 

 has been in some places extensively excavated, as near Notting- 

 ham, where it is suspected that these caves may have formed the 

 dwellings of the aboriginal Britons. 



Deposits of gypsum, or sulphate of lime, are very characteristic 

 of red marl, and this is a substance of no small importance as an 

 article of trade ; the larger masses are occasionally manufactured 

 either in the turning lathe or by hand into vases and various 

 ornaments, and are sometimes used in decorative architecture, of 

 which the columns in the hall of Keddlestone House in Derbyshire 

 are fine specimens. The coarser varieties are employed in the 

 potteries for making moulds, and some of the finer fibrous varie- 

 ties are cut into beads and broach stones of no mean beauty. 

 When heated, it loses water, and crumbles into a white powder, 

 well known as plaster of Paris, and employed for casts and a 

 variety of ornamental work. It has also been tried as a manure, 

 but not with much success in this country, nor has any light been 

 thrown upon the manner in which it operates as such. Sulphate 

 of baryta, and sulphate of strontia, have also been found in this 

 formation, but no organic remains have ever been discovered in it, 

 although theie are a few marine relics in themagnesian limestone 

 below it. 



Red mail is the last of the strata or formations, which is 

 tolerably conformable as to position with those above it, and like 

 them, neatly horizontal ; the strata of the succeeding formations 

 are said, in common geological language, to be unconformably 



