Definition of "lithology" [li•thol•o•gy]

• The gross physical character of a rock or rock formation. (noun)
• The microscopic study, description, and classification of rock. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "The lithology of the lateral has some variation and the best shows are being recorded in a dolomitic lithology, which is possibly consistent with the geology of the adjacent Elm Coulee Oil Field."
• "He said adding mud logging to Schlumberger's formation evaluation measurements also would allow more understanding of rock lithology and fluid content."
• "Overall, physiography and lithology contrast with the low mountains of the Northeastern Highlands (58), the Ridge and Valley (67), and the flat coastal plains of Ecoregions 63 and 84."