Petrology
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Petrology is the branch of geology that studies rocks, their mineralogy, composition, texture, structure and the conditions under which they form. Petrology has three subdivisions: igneous, metamorphi
A thin section of a volcanic sand grain seen under the microscope, with plane-polarized light in the upper picture, and cross-polarized light in the lower picture. Scale box is 0.25 mm.
Ljudmila Dolar Mantuani (1906–1988), first female professor of petrography in Yugoslavia
Lithology
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The lithology of a rock unit is a description of its physical characteristics visible at outcrop, in hand or core samples, or with low magnification microscopy. Physical characteristics include colour
Petrology
…with stratigraphy because it deals with the processes that form sedimentary rock. Modern sedimentary petrology is making increasing use of chemistry. Lithology was once approximately synonymous with petrography, but in current usage, lithology focuses on macroscopic hand-sample or outcrop-scale description of…
Stratigraphy as seen in southeastern Utah
A basalt, showing the 'pillow' lava shape characteristic of underwater eruptions, Italy
A claystone, the finest-grained sedimentary rock, deposited in Glacial Lake Missoula, Montana
An ultramafic mantle xenolith with olivine and pyroxene (altering brown to iddingsite) in a matrix of mafic basalt scoria