i;V II. I. JENSEN, 521 



cess the laws of volatility and condensation controlled events. 

 Now there would result an arrangement in layers in accordance 

 with the laws of specific gravity, and solubility (liquation). In 

 accordance with these laws we should probably get the following 

 arrangement from the interior outwards: — (1) Pure heavy metals; 

 (2) sulphides and oxides of the heavy metals; (3) silicates, phos- 

 phates, etc., of the heavy metals; (4) silicates of the earthy metals 

 (Ca, Ba, Mg, etc.), and of aluminium with more or less alkali; 

 (5) pure silica, carbonate of lime and smaller amounts of the 

 substances mentioned in (4). 



Most of the alkali probably still existed in the earth's primitive 

 atmosphere as chloride, sulphate and carbonate, and other salts 

 volatile at the temperature of condensation and solidification of 

 the above-mentioned substances. 



A rain of these alkaline salts would now take place on the 

 earth's surface, and at the same time the crust, in consolidating, 

 would commence to become wrinkled. Volcanic action of a most 

 intense nature would become rife, and would aid to produce the 

 earliest surface-inequalities and deformations. Frequently fissure- 

 eruptions would cause extensive flows of silicate material over 

 the cooled surface, and under the existing conditions of diminish- 

 ing temperature these magmas would assimilate the alkalies of 

 the alkaline snows. The alkaline rain still continuing, some beds 

 of alkali might escape assimilation by becoming interstratified 

 with siliceous grits formed by the erosion of primitive mountains. 

 Volcanic action would liberate more and more magmatic water, 

 and now, between a temperature of 100 J arid 300°, a very briny 

 ocean would commence to form in the depressions. As the waters 

 became cooler they would become less saline by the precipitation 

 of the salts with which they were supersaturated. We would 

 thus get FeC0 3 , MgC0 3 , CaC0 3 , K 2 S0 4 , KC1, NaCl, and 

 Fe g Cl 6 successively precipitated, and interbedded with masses of 

 siliceous detritus and with lavas. 



Assuming this order of events to have obtained, we should 

 expect the earliest crust to have consisted (when the atmospheric 

 temperature had fallen to 100°C and under) of limestones, 

 39 



