Diamonds and precious stones, a popular account of gems .. . Fig. 13.—Canccllariacancellata. Fig. 12.—Gigantic Cerithium. found ; and the cretaceous period, or period of thechalk, next in order of time. To the cretaceous period succeeded the tertiary GEOLOGICAL POSITION. 13 formation, in which are found such shells as thoserepresented by Figs. 11, 12, and 13. By this timecreatures had begun to appear bearing a strong. Fig. 14.—The Great Palseotherium. Figs. resemblance to those of the present and 15 illustrate characteristic types. After the tertiary formation comes the post-ter-tiar
Diamonds and precious stones, a popular account of gems .. . Fig. 13.—Canccllariacancellata. Fig. 12.—Gigantic Cerithium. found ; and the cretaceous period, or period of thechalk, next in order of time. To the cretaceous period succeeded the tertiary GEOLOGICAL POSITION. 13 formation, in which are found such shells as thoserepresented by Figs. 11, 12, and 13. By this timecreatures had begun to appear bearing a strong. Fig. 14.—The Great Palseotherium. Figs. resemblance to those of the present and 15 illustrate characteristic types. After the tertiary formation comes the post-ter-tiary or quarternary formation, in which the animalsare quite analogous to those of our own period. If we inquire of chemistry what is the composi- 14 PRECIOUS STONES. tion of the two grand classes of rocks above-men-tioned, we obtain this simple answer:—The calcare-ous element predominates in all sedimentary for-mations (excepting the most ancient) ; silicious andaluminous elements in igneous formations.
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectgems, booksubjectprec
