Figure F21. Downhole natural gamma and medium resistivity results from Holes 1168A, 1170D, 1171D, and 1172D. Higher gamma values are often indicative of an increased terrigenous component and/or organic material in the sediment, whereas higher resistivities are often associated with increased lithification and/or decreased porosity. The distinct lithologic change close to the Eocene/Oligocene boundary, from siliciclastic glauconitic claystone to nannofossil chalk and ooze, can be clearly seen in Holes 1168A (~260 mbsf), 1171D (~270 mbsf) and 1172D (~360 mbsf).