The Upper Nyack (UN) section of the Palisades sill is comprised principally of pigeonite-augite and augite diabases with an interstitial (remnant) glassy mesostasis. Major- and trace-metal analyses of 110 diabases, 20 being analyzed for rare-earth elements (REE), provide data regarding the source of chemical variations within the UN section and suggest a unifying theory, the propsed C-T-D Model, for differentiation within the Palisades sheet.

Preliminary work establishes that the chemostratigraphic horizons present in the type section at Englewood Cliffs (ENG)are broadly continuous from south to north and that important petrographic facies have undergone substantial mineralogic reorganization. The three most significant...