Dos veces se usa la expresi\u00f3n razones para creer en este p\u00e1rrafo. En ambos casos se aplican a generalidades vagas que no conducen a ninguna conclusi\u00f3n.<\/p>\n
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\u00a0<\/em><\/p>\n 594<\/em><\/p>\n There is one other remark connected with this subject worth making. I have given my reasons for believing that most of our great formations, rich in fossils, were deposited during periods of subsidence; and that blank intervals of vast duration, as far as fossils are concerned, occurred during the periods when the bed of the sea was either stationary or rising, and likewise when sediment was not thrown down quickly enough to embed and preserve organic remains. During these long and blank intervals I suppose that the inhabitants of each region underwent a considerable amount of modification and extinction, and that there was much migration from other parts of the world. As we have reason to believe that large areas are affected by the same movement, it is probable that strictly contemporaneous formations have often been accumulated over very wide spaces in the same quarter of the world; but we are very far from having any right to conclude that this has invariably been the case, and that large areas have invariably been affected by the same movements. When two formations have been deposited in two regions during nearly, but not exactly, the same period, we should find in both, from the causes explained in the foregoing paragraphs, the same general succession in the forms of life; but the species would not exactly correspond; for there will have been a little more time in the one region than in the other for modification, extinction, and immigration.<\/em><\/p>\n \u00a0<\/em><\/p>\n Hay otra observaci\u00f3n digna de hacerse, relacionada con este asunto. He dado las razones que tengo para creer que la mayor parte de nuestras grandes formaciones, ricas en f\u00f3siles, se depositaron durante per\u00edodos de hundimiento, y que hubo intervalos de gran extensi\u00f3n, en blanco por lo que a f\u00f3siles se refiere, durante los per\u00edodos en que el fondo del mar estaba estacionarlo o se levantaba, e igualmente cuando el sedimento no se depositaba lo bastante deprisa para enterrar y conservar los restos org\u00e1nicos. Durante estos grandes intervalos en blanco, supongo que los habitantes de cada regi\u00f3n experimentaron una considerable modificaci\u00f3n y extinci\u00f3n, y que hubo muchas migraciones desde otras partes del mundo. Como tenemos razones para creer que grandes territorios experimentan el mismo movimiento, es probable que formaciones rigurosamente contempor\u00e1neas se hayan acumulado muchas veces en espacios vast\u00edsimos de la misma parte del mundo; pero estamos muy lejos de tener derecho a sacar la conclusi\u00f3n de que ha ocurrido de este modo invariablemente, y que las grandes extensiones invariablemente han experimentado los mismos movimientos. Cuando dos formaciones se han depositado en dos regiones durante casi -aunque no exactamente- el mismo per\u00edodo, hemos de encontrar en ambas, por las causas expuestas anteriormente, la misma sucesi\u00f3n general en las formas org\u00e1nicas; pero las especies no se tienen que corresponder exactamente, pues en una regi\u00f3n hab\u00eda habido un poco m\u00e1s de tiempo que en la otra para la modificaci\u00f3n, extinci\u00f3n e inmigraci\u00f3n.<\/em><\/p>\n <\/p>\n Lectura aconsejada:<\/p>\n