GENERAL GEOLOGY

Detailed explanation-1: -Absolute dating methods determine how much time has passed since rocks formed by measuring the radioactive decay of isotopes or the effects of radiation on the crystal structure of minerals. Paleomagnetism measures the ancient orientation of the Earth’s magnetic field to help determine the age of rocks.

Detailed explanation-2: -According to the Law of Superposition, layer 1 was the first layer deposited, and thus the oldest layer. The last layer deposited was layer 12, and thus it is the youngest layer. Scientists also know that sedimentary rock generally forms in horizontal layers.

Detailed explanation-3: -Most absolute dates for rocks are obtained with radiometric methods. These use radioactive minerals in rocks as geological clocks. The atoms of some chemical elements have different forms, called isotopes. These break down over time in a process scientists call radioactive decay.

Detailed explanation-4: -The numerical ages of rocks in the Geologic Time Scale are determined by radiometric dating, which makes use of a process called radioactive decay – the same process that goes on inside a nuclear reactor to produce heat to make electricity. Radiometric dating works because radioactive elements decay at a known rate.