Earth Movements

ProfesBor Joseph Le Conté recently read a paper before the Geological Society of America, from which we learu that there are two primary and permanent kinds of moverueuts of the earth's crust - namely, those whioh canse continental surfaces and oceanic basins, and those which by interior contraction determine mountains of folded straature. These two are determined, the one by unqual radial contraction, the other by unequal concentric contraction -that is, contractiou of the interior more than the exterior. There are also two secondary kinds of movement which modify the effects of the other two and confuse oor understanding of them. These are, first, oscillatory movements, a&ecting large areas, and isostatic movements, or gravitative readjustments, by erosión and sedimentation. In the minds of sorne writers oscillatory movements have masked and obscured the effects of continent and ocean basin making, and isostasy has concealed the effects and prevented the proper interpretaron of all the others. It is believed that to make secure progresa we must keep these several kinds of movements distinct in our minds.- San Francisco Chronicle.