272 ANNUAL OF SCIENTIFIC DISCOVERY. 



eighty-three feet below the level of the Atlantic, it may be said of 

 this, that it is the salt of the Atlantic, shut off in this basin by some 

 surface change, and gradually having become very salt from concen- 

 tration in a contracting basin. But this cannot explain the occurrence 

 of salt lakes several thousand feet above the sea-level. He thinks the 

 formation of these salt lakes depends on the laws of climatology. In 

 those zones of the earth's surface where the evaporation is greater 

 than the fall of rain, and in those only, we find such saline lakes. In 

 the West of Europe, the fall of rain is greater than the evaporation ; 

 in the East the opposite is true ; in the latter we find salt lakes and 

 basins. In South America there is a prevailing wind from east to 

 west, the moisture of which is stopped by the Andes, on whose west- 

 ern side, in Peru and Chili, hardly any rain falls; amid this excessive 

 evaporation, we find salt lakes. In the southern region of South 

 America, the prevailing wind is from west to east; its moisture is 

 also stopped by the Andes, but by the western slope ; hence, on the 

 east, we have the arid plains of Southern Patagonia, where are also 

 found salt lakes. The same may be noticed in California. The con- 

 stant drainage of circumjacent districts has been bringing into insu- 

 lated basins fresh accessions of saline matter dissolved or leached 

 away from the strata over which they flow, while the evaporation un- 

 der an arid climate, carrying off the surplus water, and preventing its 

 flowing on into the general ocean, has been the means of accumulat- 

 ing in these receptacles this constantly growing supply of salt. By 

 this equilibrium between the drainage of a region and the evaporation, 

 the waters become at last so strongly impregnated as to deposit or 

 crystallize the salt upon their margins. Following up the same gen- 

 eral fact of the incessant solution of the rocks, we behold in the sea 

 itself a basin like the other salt ones, which has no outlet for its sur- 

 plus supplies but back again by evaporation into the atmosphere. 

 Looking, then, at the primeval condition of an atmosphere of aqueous 

 vapor just after the period when the earth's general temperature was 

 incompatible with this state of water, it was a fresh ocean, and not a 

 salt one. 



Prof. A gassiz remarked, that the facts and views unfolded did, as 

 the author said, furnish a new means of interpreting the ancient cli- 

 mates of the globe. From the fossil vegetable and animal organic re- 

 mains, geologists have long felt themselves provided with sensitive in- 

 dexes of the past temperatures of the earth at different periods, but 

 never until now had they been supplied with a hygrometer. This, 

 Prof. Rogers had furnished. 



In further confirmation of these views, Dr. C. T. Jackson stated, 

 that the water of the River Jordan was found upon evaporation to con- 

 tain the same ingredients as the Dead Sea into which it flowed. 



PETRIFACTION. 



SERRES and FIGUIER have discussed the conditions necessary for the 

 petrifaction of animal substances. They must be immersed in wa- 

 ter containing either largs quantities of lime-salts, or silicates. The 



