1820.] Royal Academy of Sciences. 387 



These important witnesses of the revolutions of our continent 

 have been collected by M. Delpont, Procureur du Roi at Figeac, 

 and presented to the Academy by M. Cuvier. They are depo- 

 sited in the King's cabinet, 



M. Palissot de Beauvois has acquainted the Academy with a 

 rather singular geological appearance, which he observed in the 

 county of Rowan, in North Carolina. There is found in the 

 middle of a hill formed of very fine sand mixed with small quartz- 

 ose stones, and with numerous pieces of silver-coloured mica, a 

 vein of stones so regularly placed that the inhabitants who, for a 

 long time, have noticed the appearance, give it the name of the 

 natural wall ; and some naturalists have even maintained that it 

 was a true wall, which might have been constructed in very 

 remote ages by some people now unknown. The stones have 

 generally four faces, are narrower at one of their ends, and have 

 a small notch below their top. They are ranged horizontally. 

 The kind of wall which they form is about 18 inches thick, its 

 height in the place where it is uncovered is from six to nine feet, 

 but upon digging into the ground, it has been followed to 12 and 

 18 feet deep, and it is already known to extend 300 feet, and 

 even more, in length. A kind of argillaceous cement fills the 

 intervals between the stones, and coats them externally ; each of 

 the stones is also covered with a layer of ochreous sandy earth. 



M. de Beauvois has brought some of these stones to France, 

 and upon being examined by the mineralogists of the Aca- 

 demy, they appeared to possess the characters of basalts ; but as 

 there has not as yet been found any traces of basalts or of volca- 

 noes in the United States, and as the place where this wall is 

 found is, generally speaking, of a primitive nature, it is possible 

 that this pretended wall is nothing but a bed of trap ; an amphi- 

 bohc rock very similar to certain kinds of basalts. 



We spoke in 1816 of the labours undertaken by M. Moreau 

 de Jonnes to determine the geology of the Caribbee Islands, of 

 the general ideas he had adopted on this subject, and of the 

 particular description relative to Martinique and Guadaloupe, 

 that he had presented to the Academy. He has continued the 

 arrangement of his labours, and has read a paper upon the Vau- 

 clan, one of the most remarkable mountains in Martinique, not 

 that it is the highest, but because it serves as a guide, and 

 announces this island to navigators. It has not the form of a 

 cone, hollowed at its top, but that of a prism resting on its side, or 

 of an immense basaltic ridge ; and M. de Jonnes considers it as 

 ])art of the circuit and of the edge of a very large crater, the 

 whole of which he thinks he has traced. The bottom of this 

 crater is at present a valley not only fertile, but well cultivated. 



The same author has given a geological description of Guada- 

 loupe. He finds that the western island, in which there exists a 

 soUatara in an active state, and the surface of which is about 67 

 square leagues, owes its origin to eruptions from four large sub- 

 uuirine ycjlcanoes, and that tlie eiistem island, connnonly called 



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