mass is large enough to stand the 

 waste and still reach the ground. In 

 such cases it is found to be mainly 

 stony matter and iron. No substance 

 has ever been found in any of them 

 which is not found in the earth. Only 

 a few of these shooting stars or me- 

 teorites will be seen in looking at any 

 one point in the heavens. But the earth 

 is very large and there are many such 

 points, and when these are taken all 

 together it is found that the number of 

 these little bodies which fall in a day is 

 very large. It is estimated at twenty 

 millions. But still they are small and 

 do not add very much to the size of the 

 earth. But as they are being constantly 

 swept up from space and are growing 

 fewer and fewer, and as this has been 

 going on for a very long time, it is 

 reasonable to suppose they may once 

 have been much more abundant and 

 that the earth then grew much faster 

 by reason of them. It is thought by 

 some that the earth may have grown 

 up entirely by gathering them in, the 

 idea being that it was itself once only a 

 little meteorite that succeeded in gath- 

 ering the others in. It is commonly 

 supposed, however, by those who hold 

 to this view, that the earth was formed 

 from some special cluster of these 

 meteorites that gathered together. It 

 has been thought that perhaps the gas 

 of the rings mentioned before may have 

 cooled down into little solid particles 

 before they were collected together and 

 that they built up the earth. This 

 brings the two theories together in a 

 measure. The planet Saturn, you know, 

 has rings of this kind and they are 

 made up of small solid bodies, and not 

 of gas or liquid, as was once supposed. 

 If the earth was built up this way we 

 must account for the heat in the in- 

 terior, but this would come naturally 

 enough. As the little bodies fell upon 

 the surface they would strike hot. But 

 unless they came fast they would cool 

 off before others struck the same spot 

 and the earth would not get very hot. 

 But as theygradually built upthe surface 

 the matter below would be pressed to- 

 gether harder and harder because of the 

 growing weight upon it, and this press- 

 ing together would make it hot. It is 

 figured out that it would become very, 



very hot indeed, though this might not 

 seem so at first thought, and that the 

 volcanoes and mountains may all be 

 explained in this way quite as well, and 

 perhaps better, than in the other way. 

 This is called the Accretion theory. 



It may be that neither of these theo- 

 ries is right, and we will do well to 

 hold them only as possible ways in 

 which the earth may have been formed 

 at the beginning. But, at any rate, the 

 earth has been shaped over on the sur- 

 face. In a certain sense its outer part 

 has been remade. And this concerns 

 us more than the question of its far-off 

 origin, because our soils, ores, marbles, 

 and precious stones, as well as our lands 

 and seas, are all due to this reshaping. 

 In the deepest parts of the earth which 

 we can get at for study, we find that it 

 is made up of rocks of the granite 

 class; not always granite proper, but 

 rocks like it. What is below this in the 

 great heart of the earth we do not 

 know, except that it is very dense and 

 heavy. Rocks of the granite class are 

 formed under great heat and pressure, 

 or by the cooling of molten rock ma- 

 terial. They may be called the base- 

 ment rock or great floor, on which all 

 the other rocks near the surface are laid. 

 They underlie all the surface, but at 

 different depths. In some places they 

 have been crowded up by the pressure 

 that came from the shrinking of the 

 earth, of which we spoke before, and 

 so have come to be actually at the sur- 

 face, except that soil, clay, sand, or 

 gravel may cover them. Under about 

 one-fifth of the land these rocks lie 

 just below the clays, gravels, sands, and' 

 soils that occupy the immediate surface. 

 Sometimes they come out to the actual 

 surface, and may be seen in ledges or 

 bluffs. But usually the soils, sands, 

 gravels, and clays cover them up more 

 or less deeply, but even then they are 

 often struck in sinking wells. 



Under the other four-fifths of the 

 land they lie much deeper, often sev- 

 eral thousands of feet, and there are 

 spread over them sandstones, shales,, 

 and limestones. These are the rocks 

 we usually see in the quarries and cliffs 

 of the interior states. The materials to 

 form these were taken from the older 

 rocks of the granite class by a process 



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