204 



CHALK FORMATION IN NORTH AMERICA. 



found converted into pyrites ; they resemble small fungi with a stalk 

 and rounded head. Mr. Mantell has, recently, discovered the Hip- 

 purile in chalk : it had not been found before in England. 



The vegetable remains in chalk are very few, and appear to be- 

 long to species of fuci ; but, according to M. Brongniart, in the Isle 

 ofAix, near Rochelle, there is a considerable bed of lignite in the 

 lower bed of chalk, which, he says, may have been formed of peat, 

 composed of decayed fuci and other marine plants. 



Before concluding this brief account of the organic remains in 

 chalk, it will be proper to notice an important discovery that has been 

 lately made by Dr. Morton, in the United States of America. It 

 had been asserted by M. Humboldt, that neither oolite nor chalk has 

 been found in South America, and such was generally believed to be 

 also the case in North America. At the time when M. Humboldt 

 visited South America, it was not known or even suspected, that 

 chalk and oolite might undergo a change of mineral characters, and 

 be converted into crystalline rocks, resembling primary and transi- 

 tion limestone. I believe I first discovered that the calcareous rocks 

 in Savoy, which were described by the French geologists as primi- 

 tive and transition limestones, were in reality lias, oolite, and chalk ; 

 and about the same period Dr. Buckland made a similar discovery 

 of the true character of the calcareous beds in the Alps, which had 

 been mistaken for transition rocks. It is therefore probable, that 

 many of the calcareous beds in America, may represent the chalk 

 and oolite of Europe. Dr. S. G. Morton has ascertained that there 

 are extensive beds of marl in New Jersey and Maryland, and extend- 

 ing into other states, which contain the characteristic fossils of the 

 chalk formation, particularly baculites, scaphites, ammonites, belem- 

 nites, echinites (the ananchytes ;) also bivalve and univalve shells of 

 the same epoch, together with the mososaurus and plesiosaurus. In 

 some parts this formation is covered by tertiary strata. Mr. Man- 

 tell, whose accurate knowledge of the chalk formation in England 

 will not be disputed, has received specimens of these organic remains 

 from' America, and refers them decidedly to the chalk formation, 

 though he considers that some of them are analogous to the superior 

 chalk beds at Maestricht, which are wanting in the chalk formations 

 of France and England. See Silliman's Journal, February, 1832. 



Dr. Morton is about to publish a more full account of his dis- 

 coveries. 



Between the epoch when the chalk was deposited, and the period 

 when it was covered with the tertiary strata, there appears to have 

 been a considerable interval, during which the surface of the exten- 

 sive mass of chalk was deeply furrowed and excavated, before a 

 new series of strata were deposited upon it, destined to support a 

 new creation of animals of a superior class, altogether different from 

 those which have left their remains in the subjacent strata. In some 

 situations, however, the tertiary strata appear to rest conformably on 



