GEOG 101 Lecture Notes - Lecture 10: Isua Greenstone Belt, Acasta Gneiss, Geologic Time Scale
28 Sep 2018
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Geomorphology: study of the shape of the earth"s features a(cid:374)d ho(cid:449) they cha(cid:374)ge o(cid:448)er ti(cid:373)e. Geology: the scie(cid:374)ce that deals (cid:449)ith the earth"s physical structure, a(cid:374)d substance, its history, and the processes that act on it. Timescale for geologic change: geologic timescale, division of the 4. 5 billion years since the earth formed, 4 levels, eons, eras, periods, epochs. Zircons: 4. 4 billion years old, jack hills, west australia. Acasta gneiss: 3. 8-4. 2 billion years, north territory, canada. Isua greenstone belt: 3. 7-3. 8 billion years old, southwestern greenland, stromatolite fossils, earliest life. Radiometric dating: using the rate of radioactive decay of rock elements to determine the age of rocks. The structure of the earth structure and composition. How do we know: deduced by remote sensing. Seismic waves: p (primary) waves longitudinal travels faster, speed varies with medium, s (secondary) waves shear or transverse wave, unable to penetrate through liquid. Inner core: solid fe, ni, and au (gold)
