Scientific Intelligence — Geohgy. 405 



chanical, and not chemical effects — who deny the existence of colossal dis- 

 tinct concretions, and see the columnar structure of trap, porphyry, gra- 

 nite, &c., as a mechanical effect — who believe all conglomerated rocks to 

 be of mechanical formation — that all sandstones are of mechanical origin 

 — that trap rocks have received their structure and positions through 

 volcanic agency — that granite, syenite, and porphyry, are of after forma- 

 tion to the rocks with which they are connected ; and that the apparent 

 fragments these rocks sometimes contain, are mechanical effects — will 

 obtain clearer views of the structures of the crust of the earth, and 

 their mode of formation, if they reject the mechanical hypothesis, and 

 call to their aid the chemical and contemporaneous geognostical doctrine. 



7. Do fossil organic remains of living animal species occur in any 

 of the four great classes of rocks, viz. Primitive, Transition, Secondary, 

 and Tertiary ? — At present, it is a prevailing opinion, that fossil remains 

 of living animal species occur, along with those of extinct species, in 

 rocks, as in those of the tertiary class. If, however, the late discoveries 

 of palaeontologists prove true, it follows, that all the fossil animal species, 

 even those found in the newest of the tertiary class, are extinct ; and 

 that fossil living species do not occur but in alluvial deposits. 



8. Diluvium, and Alluvium. — As the waters of the globe formerly 

 covered its whole surface, and as these waters have gradually sunk to 

 their present level, or rather as the land has gradually risen above the 

 surface of the ocean, does it not follow that the formation of diluvium and 

 alluvium commenced about the same time, and that both must occur in 

 every country, the diluvium being formed by the action of the sea, at 

 whatever height it may be found above its present level, while the allu- 

 vium is the result of the action of the atmosphere, lakes, rivers, and 

 springs ? 



9. Geology of Abyssinia. — Captains Galinierand Ferret, who are about 

 to publish at the expense of the minister of war, an account of their ex- 

 pedition to Abyssinia, have sent to the Academy of Sciences a list of the 

 subjects treated of in the four volumes of which their work will consist. 

 They have also transmitted a separate memoir on the geology of Tigre 

 and Semen. 



For the purpose of drawing up this geological description of Abyssinia, 

 and forming the map and geological sections which accompany it, the 

 authors have collected on the spot a series of specimens, which are now 

 deposited in the Jardin-des-Plantes, illustrated by sections and a num- 

 ber of notes. Their work shews that Abyssinia is a country which has 

 been subject to many geological accidents, and that these accidents 

 are of different kinds. In consequence of this complex orography, we 

 perceive from the first, that this country is necessarily very remarkable 

 in respect to its geological constitution. MM. Galinier and Ferret are 

 convinced, that if Abyssinia does not offer the complete series of forma- 

 tions to the geologist, it presents at least a great number, and that it 

 ought to be ranked among the most complex and remarkable countries 

 in a geological point of view. The formations they have met with in 

 Abyssinia, range from the first to the last degree of the geological scale. 

 Thus they have found primary and transition formations in the country 

 of the Chohos, in Tigre, Ac. ; secondary formations at the extremity of 

 Tigre and the country of the Taltals ; tertiary and modem formations 



