The Uranium-Thorium Series is a sequence of radioactive decay processes that begins with the isotope Uranium-238 and ends with stable Lead-206. This series involves several intermediate isotopes, including Radium-226 and Radon-222, which undergo alpha and beta decay over time. In nature, the Uranium-Thorium Series is significant for understanding the age of rocks and minerals through radiometric dating. The presence of these isotopes can provide insights into geological processes and the history of the Earth, making them important in fields like geology and nuclear science.