SUMMARY. v 



rital forms. Dependence of physiological gradations on the age of tha 

 formations. Geognostic horizon, whose careful investigation may yield 

 certain data regarding the identity or the relative age of formations, 

 the periodic recurrence of certain strata, their parallelism, or their total 

 suppression. Types of the sedimentary structures considered in their 

 most simple and general characters ; silurian and devonian formations 

 (formerly known as rocks of transition); the lower trias (mountain 

 Uuae-ston3, coal-measures, together with todtliegtnde and zechstein); 

 the upper trias (hunter sandstone, muschelkalk, and keuper) ; jura lime- 

 stone (lias and oolite) ; free-stone, lower and upper chalk, as the last 

 of the flotz strata, which begin with mountain limestone ; tertiary 

 formations in three divisions, which are designated by granular lime- 

 stone, lignite, and south apennine gravel pp. 271-280. 



The faunas and floras of an earlier world, and their relations to exist- 

 ing organisms. Colossal bones of antediluvian mammalia in the upper 

 alluvium. Vegetation of an earlier world ; monuments of the history 

 of its vegetation. The points at which certain vegetable groups attain 

 their maximum; cycadeae in the keuper and lias, and coniferee in the 

 bunter sandstone. Lignite and coal measures (amber-tree). Deposition 

 of large masses of rock ; doubts regarding their origin p. 288 and note. 



/. The knowledge of geognostic epochs of the upheaval of mountain 

 chains and elevated plateaux, by which lands are both formed and 

 destroyed, leads, by an internal causal connection, to the distribution 

 into solids and fluids, and to the peculiarities in the natural configura- 

 tion of the earth's surface. Existing areal relations of the solid to ihe 

 fluid differ considerably from those presented by the maps of the physi- 

 cal portion of a more ancient geography. Importance of the eruption 

 of quartzose porphyry with reference to the then existing configuration 

 of continental masses. Individual conformation in horizontal extension 

 (relations of articulation), and in vertical elevation (hypsometrical 

 views). Influence of the relations of the area of land and sea on the 

 temperature, direction of the winds, abundance or scarcity of organic 

 products, and on all meteorological processes collectively. Direction 

 of the major axes of continental masses. Articulation and pyramidal 

 termination towards the south. Series of peninsulas. Valley-like 

 formation of the Atlantic Ocean. Forms which frequently recur 

 pp. 288-297 and notes. Eamifications and systems of mountain chains, 

 and the means of determining their relative ages. Attempts to deter- 

 mine the centre of gravity of the volume of the lands upheaved above 

 the level of the sea. The elevation of continents is still progressing 

 slowly, and is being compensated for at some definite points by a per- 

 ceptible sinking. All geognostic phenomena indicate a periodical 

 alternation of activity in the interior of our planet. Probability of new 

 elevations of ridges pp. 297-306 and notes. 



g. The solid surface of the earth has two envelopes, one liquid, and the 

 other aeriform. Contrasts and analogies which these envelopes the sea 

 and the atmosphere present in their conditions of aggregation and elec- 

 tricity, and in their relations of currents and temperature. Depths of the 

 ocean and of the atmosphere, the shoals of which constitute our highland* 



