ERA OF THE OLD B, ED SANDSTONE 



31 



Limited; for instance, the Red Sea gives different polypi- 

 aria, zoophytes, and shell-fish, from the Mediterranean. 

 It is the opinion of M. Brogniart, that the uniformity 

 which existed in the primeval times can only be attribu- 

 ted to the temperature arising from the internal heat, 

 which had yet as he supposes, been sufficiently great to 

 overpower the ordinary meteorological influences, and 

 spread a tropical clime all over the globe. 



ERA OF THE OLD RED SANDSTONE — 

 FISHES ABUNDANT. 



We advance to a new chapter in this marvellous histo- 

 ry — the era of the Old Red Sandstone System. This term 

 has been recently applied to a series ot strata of enormous 

 thickness in the whole mass, largely developed in Here- 

 fordshire, Shropshire, Worcestershire, and South Wales ; 

 also in the counties of Fife, Forfar, Moray, Cromarty, 

 and Caithness ; and in Russia and North America, if not 

 in many other parts of the world. The particular strata 

 forming the system are somewhat different in different 

 countries ; but there is a general character to the extent 

 of these being a mixture of flagstones, marly rocks, and 

 sandstones, usually of a laminous structure, with conglo- 

 merates. There is also a schist showing the presence of 

 bitumen ; a remarkable new ingredient, since it is a vege- 

 table production. In the conglomerates, of great extent 

 and thickness, which form, in at 'east one district the 

 basis or leading feature of the system, inclosing water- 

 worn fragments of quartz and other rocks, we have evi- 

 dence of the seas of that period having been subjected to 

 a violent and long-continued agitation, probably from vol- 

 canic causes. The upper members of the series bear the 

 appearance of having been deposited in comparatively 

 tranquil seas. The English specimens of this system 

 show a remarkable freedom from those disturbances 

 which result in the interjection of trap ; and they are thus 

 defective in mineral ores. In some parts of England the 

 old red sandstone system has been stated at 10,000 feet in 

 thickness. 



In this era, the forms of life which existed in the Silu- 

 rian are continued : we have the same orders of marine 



