Pine Bluff daily graphic., 1906-04-29
CAUSE OF SHOCKS AND VOLCANOES


 +o day on the possible causes of the San Francisco earthquake suggest a few observations on related phenom' ena and general earth conditions that even the general reader may find in- teresting. Of the seven metropolitan dsilies calling for interviews on the morning of the disaster, every one raised, as the first question, the possi- ble connection between the eruptions of Vesuyius and the California earth cuake. This may be taken therefore to represent the general enlightened public opinion touching earth phe- romena of this class. It reflects 8 former misconception of the condi- tion of the interior when we were taught that there was but thin shell of solid rock covering a hot liquid interior
 Condition of the Earth's Interior.
 This earlier idea is still prevalent, although generally abandoned by ge- ologists and physicists of today It is no doubt more nearly true that the earth as a whole is solid. Only here and there, locally and temporarily, is there any really fused matter. Al though conclusions based OH observa- tions made in deep mines, in deep well bCres, on geysers, volcanoes, and rock strata that have been deeply buried as some time prove that the interior is highly heated, yet the over. lying burden of rock holds it under so great pressure that only where this equilibrium is temporarily neutral'Zed can fusion take place.
 Temperatures rise at the rate of about 1 degree for about every GO or TO feet of depth as the earth is pen etrated. The deep interior is threfore intensely het. much above the tenn rerature necessary for the fusion of any common rocks, but the sO-called fusion point rises rapidly with in crease of pressure, so that at the depths where temperatures are high the pressures are also high enough to keep earth matter solid. Near the center of the earth is has been esti- mated that it would probably take over 70,000 degrees to fuse ordinary Palisade trap. It is not believed that such enormously high temperatures exist anywhere in the earth, and therefore that it is practically solid through and through in spite of it's interior heat
 Volcanic Outbreaks.
 If, by any local Influence, special yelops, or if by reason of crushing or chemical change the high tempera- lures approach nearer the surface than usual, CT if, in the process of removal of surface material, by ero. sion. so much of the capping load is removed that the pressure is not suf- ticient to keep it solid then local flu s;on results The water that moro CT less saturates the rock strata is thus raised way beyond it's normal steam-forming point, and adds immen- sely to the danger of an explosion if the overlying load gives way or can be penetrated
 All of this presupposes d somewhat uneven and varying distribution of in teInal temperatures, the causes fc, which are more difficult to explain. It is perhaps sufficient, however, to say that the general cooling of the whole mass with the corresponding contrac- ton sets up stresses in the outer cold CT layers, for convenience called the crust, which causes Holdings and other displacements along the weaker NOiANo dItt IlletI lllSSS dl t Sul Cly OuC factor. Also sediments that accumu late to great thickness bury their low. ai members to depths that come with ln the highly heated zone and there undergo gradual reorganization, in- yolving the chemical recombination that geologists call metamorphls. This may add further and materially that is so essential to stratigraphic stability. In all cases. however. such disturbance is local.
 Earth Movements.
 Slow adjustments of levels are con- stantly going on in all regions. Many districts are rising and others subsid- ing with reference to mean sea level. Still others ara heinz tilted Tn the