The Earth.

Manawatu Herald, 22 November 1902, Page 2

The Earth.

* Days, months, years roll on, marking each change in the seasons, bat marking to man, but little else. With nature as we have lately shown it is very different, for with out our cognisance each day helps to an alteration which in years past have materially modified the whole aspect of the earth. These changes have been studied by geologists who have become so acquainted with its study that they read the signs the different stratas of the earth gives, so that they are able to faithfully picture the plants and animals that were upon the earth prior to any time that man was known, and by calculation and investigation they are enabled to say that the age of this world mast be. reckoned in millions years. This is necessarily a wonderfully engrossing subject but our scientists have been investigating another view of the earth which is necessarily as interesting. 0 nr earth has been subjected to great scrutiny, which causes the views previously taken of it to be greatly altered. At one time the earth was supposed to have been in a molten state all through its core, because after

descending through the crust, say fifty miles deep, a plastic layer of 150 miles deep was met with. It has been found however that after getting through this plastic layer you come to a rigid core. This has been deducted from electrical experiments. The professor has arrived at die opinion the seismic waves radiate in all directions and ha says:—-“We always find that seismic waves from points on the globe nearly opposite us travel much faster than any other waves, simple because they pass nearer to the earth’s centre or region of maximum rigidity. On the other hand, we find that waves from points on our our side of the globe travel to us more slowly, since they come along shallow chords in a less rigid region. These phenomena invariably noted at all our seismic observatories, entirely upset the old theory that the earth’s interior is a freely moving liquid, and demonstrates apparently that the earth-orange under its peel of crust, is a mass very much more rigid that the crust itself.” The earth was flung off from the sun, and since then it has been condensing and cooling. The earth’s temperature increases more and more slowly as yOu go deeper and after about 200 miles the rate of increase is hardly appreciable. The earth became Solid under two influences, one from the centre outward pressure, the other from the surface inward by cooling, and these two influences continued until a solid outer shell and a solid Inner Core came close together. At a depth of 2;)0 miles the pressure would amount to about 600 tons to the square inch, probably enough to squeeze the molten rock and metal back into a solid state. By following these arguments out, remembering that our earth is as a ball having the cruSt a certain depth, then a layer of plastic 6t great molten sea of about 150 miles in depth, and then the centre a rigid core, we get some fair explanation of one of the problems presented by earthquakes. It is pointed out that as the crust Cools it shrinks into countless wrinkles, Just as an orange withers, and when an insufficient supported area caves in, the shock goes vibrating through the earth and it lifts the crust up in long waves, like portions of a raft upon an ocean swell. There are other earthquakes which arise by fracturing due to excessive bending of the crust. To explain the working of these is unnecessary as our whole object is to show how earnest men poring into the causes of recent discoveries, have lighted upon facts which do much into putting a different interpretation of the position of the earth to that held by our predecessors of comparatively a few years ago.