EVPP 108 Lecture Notes - Lecture 18: Asthenosphere, Inner Core, Radiometric Dating

• School: George Mason University
• Department: Environmental Science and Public Policy
• Course: EVPP 108
• Professor: Kim Largen

Document Summary

Geologic time dating the rock & fossil record relative time (relative age: determined via a variety of types of evidence, including, but not limited to, Angular unconformity - sedimentary over folded/tilted sedimentary. Nonconformity - sedimentary over eroded igneous or metamorphic. Geologic correlation: unconformity, surface with very large time loss types. Nonconformity: role of radioactivity, some elements have isotopes. Version of an element with a different number of neutrons than (cid:862)(cid:374)or(cid:373)al(cid:863) (cid:894)=periodi(cid:272) ta(cid:271)le(cid:895: some isotopes are. Unstable (cid:862)de(cid:272)ay(cid:863) i(cid:374)to other ele(cid:373)e(cid:374)ts (cid:271)y e(cid:373)itti(cid:374)g parti(cid:272)les a(cid:374)d e(cid:374)ergy: radioactive isotopes radioactive decay. Original radioactive isotope (parent isotope) decays into daughter isotope rate of decay. Continental: thickness 10-70km, density ~2. 8g/cm3, granite (al, ca k-rich silicate) Oceanic: thickness 5-7km, density ~3. 0g/cm3, basalt (fe, mg-rich silicate) Thickness ~3500km, density ~10g/cm3: mostly iron, some nickel. Hot, weak, a (cid:862)plasti(cid:272) solid(cid:863) (cid:271)e(cid:272)ause it flo(cid:449)s o(cid:448)er ti(cid:373)e. Hot, liquid iron-nickel (due to lower pressure than inner)