GENERAL REVIEW. 141 



in that creative process by which the world has been 

 peopled by different and higher races during the advancing 

 periods of its geological history. How wonderful this newer 

 knowledge of life which geology imparts ! how marvellous 

 the ever-ascending yet never-completed scheme of vitality 

 it reveals ! To our forefathers the life of the present era 

 was but a repetition of the life of former ages ; to us the 

 life of the present is but a passing aspect, differing from the 

 thousand aspects that went before, but inseparably bound 

 up with them in one great scheme of ever-varying yet ever- 

 widening development. 



Such once more is the Old Red Sandstone, a system that 

 owes its interest much more to its scientific than to its 

 economic importance. Indeed, with the exception of build- 

 ing-stones used for local purposes, some indifferent lime- 

 stones, and paving-flags, such as those of Caithness andForfar, 

 there are no rocks of any commercial value among its strata ; 

 and the only accidental minerals we are aware of are oc- 

 casional poorish veins of galena, veins of baryta, salt springs 

 like those of North America, and the pebbles of agate, 

 carnelian, and the like (Scotch pebbles), obtained from the 

 amygdaloidal trap-rocks that traverse the system. Its chief 

 interest centres round its fossil fishes and Crustacea, sub- 

 jects rendered popular now more than twenty years ago by 

 the writings of Hugh Miller and Agassiz, and still attracting 

 attention by the newer forms that are year after year made 

 known by the labours of younger geologists.* And surely 

 what geologists are labouring to reveal, the man of ordinary 

 intelligence may make some effort to comprehend and en- 



* We allude in particular to the labours of Professor Pander among 

 the Old Red fishes of Russia ; the numerous discoveries of new crusta- 

 ceans and fishes in the flagstones of Forfarshire by Mr Powrie ; and 

 the long-continued observations of Dr Gordon among the sandstones of 

 Moray and Ross-shire. 



