"Geology," "Earth science" and "geoscience" are different terms with the same literal definition: the study of the Earth. In the academic world and the professional realm, the terms may be interchangeable or have different connotations based on how they are being used. Over the last few decades, many colleges and universities have changed their geology degrees to Earth science or geoscience or added those as separate degrees altogether.
Geology is the root of Earth science. Academically they were termed "natural philosophers,". The first meaning of the word geology, in the 1700s, was a treatise, a "theory of the Earth". The earlier "geologists" of medieval times were inquisitive, cosmological theologians who treated the Earth by analogy to the body of Christ and paid scant attention to rocks. They produced some erudite discourse and fascinating diagrams, but nothing that we would recognize as science. Today's Gaia hypothesis might be thought of as a New Age version of this long-forgotten worldview.
Geologists are the ones who explored the rocks, mapped the mountains, explained the landscape, discovered the Ice Ages, and laid bare the workings of the continents and the deep Earth. Geologists are the ones who found aquifers, planned mines, advised the extractive industries, and laid straight the road to wealth based on gold, oil, iron, coal, and more. Geologists put the rock record in order, classified the fossils, named the eons and eras of prehistory, and laid out the deep foundation of biological evolution.
About 'Earth Science' and 'Geoscience'
Earth science and geoscience gained currency with newer, more interdisciplinary tasks that build upon the work of geologists. To put it simply, all geologists are Earth scientists, but not all Earth scientists are geologists.
Today, an Earth science or geoscience degree entails a much wider realm of subjects than a traditional geology degree. It studies all of Earth's dynamic processes, so typical coursework may include oceanography, paleoclimatology, meteorology, and hydrology as well as normal "traditional" geology courses like mineralogy, geomorphology, petrology, and stratigraphy.
Maybe it's all just a matter of language. "Earth science" and "geoscience" are as straightforward in English as "geology" is in scientific Greek.
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