Radiometric Grid of Australia (Radmap) v4 2019 ratio uranium over thorium

The uranium over thorium grid is a derivative of the 2019 radiometric or gamma-ray grid of Australia which is a merge of over 600 individual gamma-ray spectrometric surveys. The radiometric, or gamma-ray spectrometric method, measures the natural variations in the gamma-rays detected near the Earth's surface as the result of the natural radioactive decay of potassium (K), uranium (U) and thorium (Th). The data are collected on airborne geophysical surveys conducted by Commonwealth, State and Northern Territory Governments and the private sector. The 2019 uranium over thorium grid has a cell size of about 100 m (0.001 degrees) and is derived from the filtered uranium and thorium grids.