To determine the ages in years of Earth materials and the timing of geologic events, geologists utilize the process of radiometric decay. Radiometric dating calculates an age in years for geologic materials by measuring the presence of a short-life radioactive element, e.g., carbon-14, or a long-life radioactive element plus its decay product, e.g., potassium-14/argon-40. The[…]
Scientists discovered a living microbial mat that uses arsenic instead of oxygen for photosynthesis and respiration. Introduction Billions of years ago, life on Earth was mostly just large slimy mats of microbes living in shallow water. Sometimes, these microbial communities made carbonate minerals that over many years cemented together to become layered limestone rocks called[…]
Geologist and cartographer Tharp changed scientific thinking about what lay at the bottom of the ocean. Introduction Despite all the deep-sea expeditions and samples taken from the seabed over the past 100 years, humans still know very little about the ocean’s deepest reaches. And there are good reasons to learn more. Most tsunamis start with[…]
The geological history of the Earth can be broadly classified into two periods: the Precambrian supereon and the Phanerozoic eon. Introduction The geological history of Earth began 4.567 billion years ago, when the planets of the Solar System were formed out of the solar nebula, a disk-shaped mass of dust and gas left over from the formation[…]
The Earth has been through many changes during its existence. Introduction Modern geologists and geophysicists consider the age of Earth to be around 4.54 billion years (4.54×109 years). This age has been determined by radiometric age dating of meteorite material and is consistent with the ages of the oldest-known terrestrial and lunar samples. Following the[…]
Touring with urban geology in mind. By David B. Williams In this age of concrete and glass, it may seem anachronistic to look at building stone. But, for centuries, stone has been the material of choice, and it is still the material chosen by architects and designers around the globe. Whether it’s a bank covered[…]
Geoarchaeology in action: the story of the River Tyburn from 11,500 years ago to the present. Originally published by Museum of London Archaeology (MOLA), republished with embed permission for educational, non-commercial purposes.
Looking at the Precambrian and Phanerozoic Eons. Introduction The geological history of Earth follows the major events in Earth’s past based on the geological time scale, a system of chronological measurement based on the study of the planet’s rock layers (stratigraphy). Earth formed about 4.54 billion years ago by accretion from the solar nebula, a[…]