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1. The gross physical character of a rock or rock formation.
2. The microscopic study, description, and classification of rock.

lith′o·log′ic (lĭth′ə-lŏj′ĭk), lith′o·log′i·cal adj.
lith′o·log′i·cal·ly adv.
li·thol′o·gist n.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
References in periodicals archive ?
Mineralisation lies almost entirely within the mafic units, being both lithologically and structurally controlled.
Lithologically, the Bara Formation is mainly composed of sandstone which is interbedded with conglomeratic sandstone, siltstone, carbonaceous shale, and mudstone.
Poisson ratio is lithologically sensitive and helps in distinguishing sandstone from mudstone, in reservoir characterization, and fluid identification.
The guide deems the traditional topostratigraphic framework obsolete, thus affecting the validity of the 'Latorp', 'Lanna' and 'Holen' limestones, as well as many other regional Ordovician units (for reference, topostratigraphy employs a mixture of lithologically and palaeontologically defined boundaries in stratigraphic units; Jaanusson 1960b).
Lithologically, the Late Paleocene Patala formation in Upper Indus Basin contains Calcareous Shale with alternative coal seams whereas, in study area it comprises of Greenish Grey Carbonaceous Shale with occasional Pyritic nodules; marl and white to grey nodular limestone while coal is present in abundance in middle part of the rock unit.
The Beulah Camp Formation is lithologically similar to the Grant Brook Formation and this correlation is corroborated by the chemical data.
Lithologically, this portion is generally characterized by poorly bedded and indurated massive to thinly bedded shales.
These successive phases of advance and retreat led to the deposit and erosion of lithologically contrasted layers, including moraines, glaciolacustrine, and deltaic sediments.
Lithologically the landslide consisted of the weathered boulders of limestone and dolomite of varying size were embedded in clay matrix.