S98 AGGLOMEllATED LIMESTONES. 



tageous circumstances than I was myself, may direct tbcir 

 researches. 



XII. AGGLOMERATE LIMESTONE or THE BARIGON, OP 

 THE CASTLE OF CUMANA, AND or THE VICINITY OF 

 POBTO CABELLO. This is a very complex formation, pre- 

 senting that mixture and that periodical return of compact 

 limestone, quartzose sandstone, and conglomerates (lime- 

 stone breccia) which in every zone peculiarly characterises 

 the tertiary strata. It forms the mountain of the castle of 

 San Antonio near the town of Cumana, the south-west 

 extremity of the peninsula of Araya, the Cerro Meapire, 

 south of Caraco, and the vicinity of Porto Cabello. It con- 

 tains (1) a compact limestone, generally of a whitish grey, or 

 yellowish white (Cerro del Barigon), some very thin layers ot 

 which are entirely destitute of petrifactions, while others are 

 filled with cardites, ostracites, pectens, and vestiges of litho- 

 phyte polypi : (2) a breccia in which an innumerable number 

 of pelagic shells are found mixed with grains of quartz 

 agglutinated by a cement of carbonate of lime : (3) a cal- 

 careous sandstone with very fine rounded grains of quartz 

 (Punta Arenas, west of the village of Maniquarez), and con- 

 taining masses of brown iron ore : (4) banks of marl and 

 slaty clay, containing no spangles of mica, but enclosing 

 selenite and lamellar gypsum. These banks of clay appeared 

 to me constantly to form the lower strata. There also 

 belongs to this tertiary stratum, the limestone tufa (fresh- 

 water formation) of the valleys of Aragua near Vittoria, and 

 the fragmentary rock of Cabo Blanco, westward of the port 

 of La G-uayra. I must not designate the latter by the name 

 of nagelfluhe, because that term indicates rounded frag- 

 ments, while the fragments of Cabo Blanco are generally 

 angular, and composed of gneiss, hyaline quartz, and chlo- 

 ritic slate, joined by a limestone cement. This cement 

 contains magnetic sand,* madrepores, and vestiges of bivalve 

 sea shells. The different fragments of tertiary strata which 

 I found in the littoral Cordillera of Venezuela, on the two 

 slopes of the northern chain, seem to be superposed near 

 Cumana (between Bordones and Punta Delgada) ; in the 



* This magnetic sand no doubt owes its origin to chloritous slate, 

 which, in these latitudes, forms the bed of the sea. 



