INDUSTRIAL GEOLOGY. 143 



learn where to look for rich soils, and may gain data whereby to judge the agri- 

 cultural probabilities of each State and section of our country. Let us examine 

 the methods of nature as exhibited by this science, and interrogate the science 

 itself as to the resources, present and prospective, of our beloved Michigan. 



The crystallization of the older rocks, the changing of wood into stone coal, 

 the formation from coarse rock material of such gems as rubies, emeralds and 

 diamonds, the baked and altered condition of many rocks, has convinced all 

 students that our earth was once a molten mass, red-hot, aye white-hot, like our 

 present sun, and yet this ball of fire went swinging through space then as to- 

 day. The form of the earth — an oblate spheroid bulging at the equator and 

 flattened at the poles — is just what it must have become as a melted sphere, 

 rolling on its axis so rapidly that each point on the equator moved 25,000 miles 

 each 24 hours. Every farm boy knows of centrifugal force, though he may 

 never have heard the word in his life. Has he not watched the water as it flew 

 from the grind-stone, flying further as he turned faster ? If he turns slowly, 

 the water, by its adhesion, adheres to the stone, and does not fly off at all. 

 Could the lad turn fast enough the centrifugal force would finally burst the 

 stone, as is not infrequently the case with large wheels connected with steam 

 engines. We know now how this centrifugal force is made our servant, as when 

 the bee-keeper uses it to tbrow the beautiful liquid honey clean from the comb. 

 Now, in those early first days, the rapid revolutions of the earth tended to 

 throw its parts off, and most at the equator. Gravitation pulled in the opposite 

 direction, and while she could not prevent all her large family of liquid particles 

 from crowding out, she could attract sufficiently to prevent any from entirely 

 leaving the old home. You see that then, as to-day, it took attraction to keep 

 all the family at home. 



Exact mathematical calculation proves that the form of the earth is just what 

 it w^ould be if liquid, and controlled by these two forces: the centrifugal force 

 consequent upon its daily revolution and the force inherent in matter which we 

 call gravity. This, then, is another proof that our world was once a molten 

 mass. The increasing heat as we go towards the centre of the earth, and the 

 fact of earthquakes and volcanoes are often given as added proofs that the early 

 condition of our sphere was a molten one. Of course you already know that 

 we find imbedded in the rocks the remains of the old-time life — ancient plants 

 and animals. These fossils, as we call them, show that the earth's surface in 

 the early ages was equally warm at pole and equator. No chance then, you see, 

 for martyrs to north pole expeditions. In those old rock fossils, even of Green- 

 land, we find remains of palms and tropical animal life like corals ; thus we 

 know that in the childhood and youth of our planet, tropic heat bathed the 

 poles as it to-day warms the equator. 



Now, how can we account for this extra heat in the earlier years of our 

 earth sphere? It is not likely that the sun regarded us any more warmly then 

 than now. If the earth cooled from a melted condition, heat would be con- 

 stantly given out, and for ages the heat from the interior furnace would be far 

 more than that sent down from the solar chandelier, and hence the more than 

 tropical heat that bathed the young world from pole to pole. The strength 

 and vigor of our earth would seem to disapprove the modern notion that a hot- 

 house is not a good place in which to bring up children. 



Many geologists think that the world is still molten at the center. Others 

 think that the center is solid. All think it is hot, but the latter class just 

 referred to think that the added pressure and consequent density and solidity 

 at the earth's center have raised the melting point, so that, though while there 



