This study complements Delaware Geological Survey Bulletin No. 17 and deals exclusively with clays and clay-size minerals. The cored section at the location of Je32-04 has been subdivided into 25 clay zones on the basis of major changes in trends and degree of crystallinity of clay minerals. The composition of clay minerals varies from zone to zone. These clay minerals have been identified: kaolinite, berthierine, chlorite, illite, smectite, chlorite/smectite, illite/smectite, glauconite/smectite, and glauconite pellets.

The non-marine Cretaceous sediments of northern Delaware older than the Magothy formation cannot be divided accurately into formations or mappable geologic units because their lithologic characteristics are very similar. However, two heavy mineral zones can be distinguished in these deposits: a lower staurolite-kyanite-tourmaline-zircon zone, and an upper tourmaline-zircon-rutile zone with abundant alterites. They have been named the Patuxent zone and the Patapsco-Raritan zone respectively.