The shape of a gamma ray (or SP) log through a sand body is often thought of as a grain size profile. Three basic log shapes are recognized: funnel (coarsening upward), cylinder (blocky), and bell (fining upward) ([[:file:quick-look-lithology-from-logs_fig1.png|Figure 1]]). These three shapes can be subdivided into smooth (relatively homogeneous) or serrate (with interbedded thin shales). | The shape of a gamma ray (or SP) log through a sand body is often thought of as a grain size profile. Three basic log shapes are recognized: funnel (coarsening upward), cylinder (blocky), and bell (fining upward) ([[:file:quick-look-lithology-from-logs_fig1.png|Figure 1]]). These three shapes can be subdivided into smooth (relatively homogeneous) or serrate (with interbedded thin shales). |