Geology (from the Greek γῆ, gê, “earth” and λόγος, logos, “study”) is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates. In modern times, geology is commercially important for mineral and hydrocarbon exploration and for evaluating water resources; is publicly important for the prediction and understanding of natural hazards, the remediation of environmental problems, and for providing insights into past climate change; plays a role in geotechnical engineering; and is a major academic discipline. Geology is also a hobby for those who enjoy collecting various rocks, minerals and/or fossils.
Mineralogy is the study of chemistry, crystal structure, and physical (including optical) properties of minerals. Specific studies within mineralogy include the processes of mineral origin and formation, classification of minerals, their geographical distribution, as well as their utilization.
Paleobotany, also spelled as palaeobotany (from the Greek words paleon = old and “botany”, study of plants), is the branch of paleontology or paleobiology dealing with the recovery and identification of plant remains from geological contexts, and their use for the biological reconstruction of past environments (paleogeography), and both the evolutionary history of plants, with a bearing upon the evolution of life in general.
Paleontology from Greek: “old, ancient”, “being, creature”, “speech, thought” is the study of prehistoric life. It includes the study of fossils to determine organisms’ evolution and interactions with each other and their environments (their paleoecology). As a “historical science” it attempts to explain causes rather than conduct experiments to observe effects.
Petrology (from Greek: πέτρα, petra, rock; and λόγος, logos, knowledge) is the branch of geology that studies rocks, and the conditions in which rocks form.
Lithology was once approximately synonymous with petrography, but in current usage, lithology focuses on macroscopic hand-sample or outcrop-scale description of rocks, while petrography is the speciality that deals with microscopic details.
Sedimentary rocks cover most of the Earth’s surface, record much of the Earth’s history, and harbor the fossil record. Sedimentology is closely linked to stratigraphy, the study of the physical and temporal relationships between rock layers or strata.
Stratigraphy, a branch of geology, studies rock layers and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks. Stratigraphy includes two related subfields: lithologic stratigraphy or lithostratigraphy, and biologic stratigraphy or biostratigraphy.