Show marth earth movement professor joseph le conte Conto recently read a paper before befaro the geological society of america amerian from which we learn that there ther 6 are two primary and perma ernis nent kinds of movements of the earths crust namely those which cause continental tinetta tin 1 surfaces and oceanic basins and those which by interior contraction determine mountains of folded structure these two are determined the one by radial contraction the other by unequal concentric contraction that is contraction of tho the interior more than the exterior there are also two secondary kinds of movement which modify the effects of the other two and confuse our understanding of cf them these are first oscila oscillatory a tory movements affecting large areas and movements or readjustments just ments by erosion and sedimentation in the minds of some writers oscillatory cill atory movements have masked ai and I 1 d obscured the effects of continent and ocean basin making and stasy has concealed the effects and prevented the proper interpretation of all ah the others it is believed that to make secure progress we runs must keep these several kinds of amov movements cements distinct in our minds san ban francisco chronicle Chro niclo |