378 ENUMERATION OF STRATA. 



true, and independent of the progress of positive gtology in 

 other countries ; while the systematic names applied to any 

 particular formation of America, are founded only on the 

 supposed analogies between the formations of America and 

 those of Europe. Now those names cannot remain the 

 same, if after further examination, the objects of comparison 

 have not retained the same place in the geologic series ; if 

 the most able geologists now take for transition-limestone 

 and green sandstone, what they took formerly for zechsteiu 

 and variegated sandstone. I believe the surest means by 

 which geologic descriptions may be made to survive the 

 change which the science undergoes in proportion to its pro- 

 gress, will be to substitute provisionally in the description 

 of formations, for the systematic names of red sandstone, 

 variegated sandstone, zechstein, and Jura limestone, names 

 derived from American localities, as sandstone of the Llanos, 

 limestone of Cumanacoa and Caripe, and to separate the 

 enumeration of facts relative to the superposition of soils, 

 from the discussion on the analogy of those soils with those 

 of the Old World.* 



* Positive geography being nothing but a question of the series or 

 succession (either simple or periodical) of certain terms represented by the 

 formations, it may be necessary, in order to understand the discussions 

 contained in the third section of this memoir, to enumerate succinctly 

 the table of formations considered in the most general point of view. 



I. Strata commonly called Primitive ; granite, gneiss, and mica-slate 

 (or gneiss oscillating between granite and mica-slate) ; very little primitive 

 clay- slate ; weisstein with serpentine ; granite with disseminated amphi- 

 bole; amphibolic slate; veins and small layers of greenstone. 



II. Transition strata, composed of fragmentary rocks, (grauwacke,) 

 calcareous slate, and greenstone . earliest remains of organized existence : 

 bamboos, madrej.ores, producta, trilobites, orthoceratites, evamphalites). 

 Complex and parallel formations j (a) Alternate beds of grey and stratified 

 limestone, anthracitic mica-slate, anhydrous gypsum, and grauwai ke ; (A) 

 Clay-slate, black limestone, grauwacke with greenstone, syenite, transition- 

 granite, and porphyries with a base of compact felspar ; (c) Euphotides, 

 sometimes pure and covered with jasper, sometimes mixed with amphibole, 

 hyperstein, and grey limestone ; (d) Pyroxenic porphyries with amygda- 

 loides and zirconian syenites. 



III. Secondary strata, presenting a much smaller number of monocoty- 

 ledonous plants ; (a) Co-ordinate and almost contemporary formations with 

 red sandstone (rothe todtes liegende), quartz-porphyry, and fern-coal. 

 These strata we less connected bv alternation than by opposition. The 



