Knowra Lithology Lithology Lithology describes and studies rocks through physical characteristics such as composition, grain size, texture, and color. It is used to distinguish and classify rock units.
Igneous rock : Rock formed when molten magma or lava cools and solidifies. Its mineral composition and crystal texture distinguish intrusive and volcanic lithologies.
Geologic map : A map showing the distribution, boundaries, and ages of geological units at Earth’s surface. Mapped units are commonly differentiated and labeled by lithology.
Petrology : The branch of geology that investigates the origin, composition, structure, and history of rocks. Petrology explains rock formation and evolution; lithology emphasizes description and classification.
Grain-size scale : A classification system that groups sediment particles by their measured diameter. Standardized size classes make clastic lithologic descriptions comparable.
Lithostratigraphic unit : A formal rock body defined and named by observable lithologic characteristics and stratigraphic position. Lithologic properties provide the basis for defining and mapping these rock units.
Sedimentary rock : Rock formed through sediment accumulation, precipitation from solution, or biological processes. Its grains, cement, and bedding create diagnostic lithologic descriptions.
Well log : A record of measurements made in a borehole to characterize rocks and fluids underground. Lithologic interpretation uses well logs to identify subsurface rock intervals.
Stratigraphy : The study of layered rocks, their sequence, distribution, and relationships through time. Stratigraphy concerns rock-layer relationships, while lithology concerns rock characteristics.
Folk classification : A carbonate-rock classification based on grain types, matrix, and depositional texture. It converts carbonate composition and texture into systematic lithologic names.
Unconformity : A surface representing a gap in the geological record caused by erosion or nondeposition. A lithologic change across an unconformity may accompany missing geological time.
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