Step-2 Identify the 50% clay
content on the Natural Gamma Log.
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Gamma counts correspond to clay content. The 50%
clay line is generally midway between the high and low gamma peaks. (50 Counts
per Second or 100 API units) Deflections to the right of this line are shales
and clays(further right). Deflections
to the left are Sandstone, Limestone or Coal. (In typical strata.) Note: This
method is not valid for Uranium bearing strata.