of the United States. 37 



by beds of white sand, pebbles and porcelain clay. I am 

 rather inclined to arrange the sand of New-Jersey in the 

 same class ; but future observations must determine this 

 point. 



Philadelphia is built upon a plastic clay and sand forma- 

 tion ; the sand is of variegated hues ; the clay, which is 

 very pure, is found at thirty feet below the surface of the 

 ground. 



At Cape Sable, in Maryland, vast beds of lignite are 

 found, containing amber, which has been described by Dr. 

 Troost in the American Journal of Science. It is well 

 known that the amber of Prussia is found in a similar situa- 

 tion, and thus in distant parts of the world similar strata 

 contain the same mineral substances ; and the amber of the 

 Baltic has an ally and a brother in the formations of plastic 

 clay, sand, and lignite, at Gay Head, Bordentown and Cape 

 Sable. 



The clays of this formation abound in Florida ; speci- 

 mens are deposited in the cabinet of the Academy of Natu- 

 ral Sciences in Philadelphia, from Escambia bay, seven 

 miles above Pensacola, and from Mobile bay in Alabama. 



I am informed by Major Ware, who has travelled over 

 great part of the southern frontier of the United States, that 

 the plastic clay extends over several hundred square miles, 

 in a direction south and south-east of the Chicasaw Indians. 

 In the tract of country which this embraces, in every exca- 

 vation which the inhabitants make to obtain water, they dig 

 up a fine dark red clay, which in some instances they use 

 to paini their houses ; the surface is composed sometimes 

 of the clays and sometimes of the sands of this formation. 



Another situation where it appears in a very conspicuous 

 station, and with prominent characters, is at Chicasaw 

 Bluffs and at Natchez, which have been described by Mr. 

 Nuttall under the term alluvial, in his tour to the Arkansas. 

 It also abounds in many other situations, and on a reference 

 to Cleveland every locality which is noticed as affording 

 porcelain and potter's clay, may be considered as belong- 

 ing to this formation. Its exact geographical boundaries 

 can pnly be determined in the course of time, when the ter- 

 tiary formations of America have attracted that attention 

 which it is the object of this essay to awaken. The extent 

 of it may be considered a subject of congratulation to the 



