Water Resources Program fact sheet
Missouri Geological Survey Director: Joe Gillman, RG

    There are four columns on hand-drawn geologic well logs including the Residue Column, the Percentage Column, the Rock Column and the Description Column. The computer-generated logs contain three columns including the Residue Column, the Percentage Column and the Description Column. 

    The Residue Column contains information describing the colors and textures of any shale, quartz, chert and silicified fossils that remain after the rock cuttings are digested in hydrochloric acid. The Percentage Column contains information describing the percentage and lithology of each rock type present in undigested rock cuttings. The Rock Column is used to describe the color and crystalline texture of the carbonate rock (hand-drawn logs only). The Description Column on hand-drawn logs contains chemical formulas of any associated minerals and any additional information about the rock. The Description Column on computer-generated logs contains information about associated minerals and rock color and crystalline texture.

    Wells Log - Computer and Hand-drawn illustration

    Well Log Symbols Key

    The colors and symbols are categorized according to the column(s) in which they appear on the logs. The column in which a color or symbol resides defines the meaning of that color or symbol. 

    Wells Log percentage column and lithology symbols illustration
    Wells Log rock column colors and symbols illustration
    Wells Log residue column and symbols illustration

    Well Drilling Logs Viewer

    Well Drilling Logs Viewer - Locate, display and download well logs

    Nothing in this document may be used to implement any enforcement action or levy any penalty unless promulgated by rule under chapter 536 or authorized by statute.

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