1 82 GEOLOGY. 



ly that the time occupied in cooling the earth from its 

 melted state, sufficiently to form a crust, was longer than 

 all the time of the ages which were occupied in laying- 

 down the strata that contain fossils that is, longer than 

 all palaeozoic, mesozoic, and cainozoic time. And if the 

 earth, as is supposed by many geologists, was once so 

 heated as to be in a vaporous state, the time of cooling 

 must have been vastly longer than this. But, whether 

 we reckon the azoic or lifeless age of the earth as begin- 

 ning with the first solidification of the crust, or with the 

 melted state, or extend it back to the supposed vaporous 

 or nebulous state, so called, the time that elapsed before 

 any life appeared on the earth was immense in length. 



264. Floor of the Earth's Crust. It was in the solidifi- 

 cations of the Azoic age that the floor, as we may term 

 it, of the earth's crust was laid. This floor lies over the 

 melted matter which is inclosed still within the crust, and 

 which constitutes by far most of the bulk of the globe. 

 It is not an even floor, although it was laid down in hor- 

 izontal strata. It has been bent, and folded, and frac- 

 tured, and lifted up, and broken through by melted mass- 

 es forced upward from below. Although, then, its stra- 

 ta were laid before any of the fossiliferous strata, yet, 

 from these bendings and upheavals, they appear in some 

 parts of the earth upon the surface of its crust, the fos- 

 siliferous rocks skirting their prominences or partially 

 overlying them. 



265. Changes in the Azoic Rocks. Vast changes oc- 

 curred in the azoic rocks during both the Azoic age and 

 the succeeding ages, for fire and water were at work 

 upon them more or less during all that time. Just as 

 soon as solidification took place on the surface of the 

 great melted ball which once constituted our earth, n, 

 large part of the steam surrounding it was condensed 

 into water, which of course fell in rain. At the same 

 time, the forming crust, as is the case with all matter ex- 

 cept water, in passing from the melted to the solid state, 



