GEOL 1121 Lecture Notes - Lecture 3: Cosmic Ray, Geochronology, Exponential Decay
17 Mar 2018
School
Department
Course
Professor
Document Summary
Relative: rock a is older than rock b. Superposition: in a set of layers, the lowermost is the oldest. Unique fossils occur in rocks of same age, so layers can be correlated between localities i. e. the layers are age-equivalent . Correlation of unique fossils between locations constrain time. Isotopes: same element but different number of neutrons, and thus atomic mass; the. 238 and 235 refer to atomic mass, and the isotopes are referred to as 238u and 235u. Some isotopes undergo spontaneous decay to a new element. Ejection of particle from nucleus or capture of electron by nucleus. Change in number or protons, and in some cases atomic mass. Radioactive decay generates heat, and much of internal heat of. Earth from decay of 238u, 235u, 232th, and 40k. Sand empties from top to bottom it takes a fixed amount of time.
