sand is well exposed most of way N to where main clay in & minable. It is thick thruout most this area, typically tabular x-lay and with local silty lenses and, in one place a shale lense. Where main bed in W of Denver Sewerpipe mine the ss is noticeably thinner and not cliff forming. Need measurements to prove rate thinning but it looks abrupt. May be some correlation between thinning of 1st Glen and thick main clay in this area. Second clay has top beat. clay, but is thin thruout area in question. So-called platy beds not prominent & consist chiefly of ss in thicker beds than typical platy. No fossils. zone nearly Fe. Starned.