Silicious Deposit. 145 



low, at the period when the rocky beds were thrown into their in- 

 cUned state, in which they now he about the sahnes on the Musk- 

 ingum river. We have proof that this stratum was formed under 

 water, from the imbedded animal remains, found through its whole 

 length, and also that these are marine shells, and of course lived in 

 salt water. Mr. Bakewell, when speaking on the subject of sili- 

 cious deposits, says, " we know no instances in nature, of silicious 

 earth being held in aqueous solution, except in waters of hot or boil- 

 ing springs ; and hence it seems reasonable to infer that many sihcious 

 rocks and veins have been deposited from subterranean waters at 

 high temperatures. In other instances, silicious earth, rendered fu- 

 sible by-an intermixture with alkalies and earths, may have been 

 poured over the bed of the ocean, and by gradual refrigeration, the 

 constituent parts may have separated and formed granite rocks, com- 

 posed of quartz, feldspar, mica and hornblende. Beds of limestone 

 may have been formed by similar calcareous eruptions, in which" 

 the lime was sometimes in solution, and sometimes mechanically 

 suspended. Nor is it necessary to suppose, that these aqueous 

 eruptions were always sudden, and attended with violent convul- 

 sions ; for when a passage was once opened, they may have risen 

 slowly, and been diffused in a tranquil state, and by gradual conden- 

 sation, may have enveloped the most delicate animals and vegeta- 

 bles, without injuring their external form. The long intervals of 

 repose, between these aqueous eruptions, saturated with mineral 

 matter, may have allowed time for the growth and decay of animals 

 whose remains are found in different strata, whilst the formation of 

 others may have taken place under circumstances incompatible with 

 organic existence, and accordingly we find in the rocks most abound- 

 ing with organic remains, certain strata, in which they rarely, or 

 never occur. The same agent which enveloped living animals in 

 mineral matter without injuring their external form, appears in some 

 instances to have immediately arrested vitality. Petrified fish have 

 been discovered in solid rock, which appear to be in the very atti- 

 tude of seizing and swallowing their prey.* A sudden eruption of 

 hot fluid, saturated with the different earths, might destroy in a mo- 

 ment, the animals previously existing, and form around them a sili- 

 « , . 



* Mr. Bakewell examined the celebrated specimen here alluded to, which is 

 in one of the museums of Paris, and concluded that the heads of the fishes were 

 merely pressed against each other. — Ed. 



Vol. XXIX.— No. 1. 19 



