Question

Geologists use the natural radioactive decay of elements as the foundation for relative time dating.​ a. true b. false

Answer 1

Geologists use radiometric dating, based on radioactive decay, to determine the exact age of geological materials. This process, key to absolute dating, measures the ratio of parent and daughter isotopes to estimate the material's age. The assumptions made include no initial daughter isotopes and a closed system.

Step-by-step explanation:

Geologists indeed utilize the natural radioactive decay of elements as a fundamental method for dating various geological materials such as rocks and fossils. This process is characterized as radiometric dating. It is particularly helpful for determining the absolute age of a subject material by analyzing the ratio between the parent and daughter isotopes present within.

When using radiometric dating, a couple of assumptions are made. Firstly, it is presumed that no daughter atoms were present when the material first formed. Secondly, the subject material is assumed to have remained a closed system since its formation. These assumptions are essential to generate accurate age calculations.

Contrastingly, relative dating is another method used by geologists to determine the sequence of events in Earth's history without necessarily providing numerical ages. However, for exact age determination, absolute dating techniques, particularly those employing radioactive isotopes, are applied.

Answer 2

True. Geologists do use the natural radioactive decay of elements as the foundation for relative time dating.

This method is based on the fact that certain isotopes of elements are unstable and decay over time, transforming into different elements or isotopes. The rate at which this decay occurs is known as the half-life, which is the time it takes for half of the parent isotope to decay into the daughter isotope.

By measuring the ratio of parent to daughter isotopes in a rock or mineral sample, geologists can determine how long it has been since the rock formed or the mineral crystallized. This provides a relative age for the sample compared to other rocks or minerals.

For example, if a sample has a high ratio of parent to daughter isotopes, it indicates that it is relatively young because less time has passed for the parent isotope to decay. Conversely, a low ratio indicates that more time has passed, and the sample is older.

Geologists use several different radioactive isotopes for relative time dating, depending on the age range they are studying. Some commonly used isotopes include uranium-lead, potassium-argon, and carbon-14.

Overall, the natural radioactive decay of elements is a fundamental tool used by geologists to determine the relative ages of rocks and minerals, helping them piece together the geological history of Earth.