Lakote-Morrison contact.- As in other nearby sections the basal Morrison cll locally sits on dark gray non-cllc. claystone which grades downward into clle. green + red ver. clle. claystone without the slightest sign of a break in sedimentation. This change studied closely at W-18 (see p. 36 this ntbk), where the clle-nonclle change takes place in an inch of greenish gray +gray claystone. Some banding of slt. green + gray is present but both occur on either side of change so that the color break between green (or ver red+ green) + gray does not correspond to the change from clle to nonclle. Consequently in this area 3 choices for placing this contact. 1) at clle- nonclle break [See the cylc ls + clle claystone in W-13 cabin creek- to illustrate worthlessness of this criterion] 2) at color change in claystone [illogical on grounds that it is obviously a gradation + that Morrison elsewhere has gray+dk-gray clystone in it] 3) at base massive cylc ss. [only logical break locally] 45