Age Unit Ft. Description Interpretation Siltstone, tan and yellow with thin limonite ledges. Overbank soil with periodic flood episodes. Siltstone and sandstone interbeds, medium grey, poorly developed bedding, sub-rounded clasts of lignitized wood and charcoal. Overbank deposits of the distal levee, recording periodic flood episodes and channel migration away from area. Clay; medium grey, unbedded slightly fissle, basal contact downcutting and sheathed with limonite abundant lignitized conifer logs in 6.5 feet above base. Abandoned channel filled with fine-grained sediment and logs transported during high-water episodes. Siltstone: mottled grey and yellow with limonite crusts, and clay rip-up clasts at base, coarsens upwards to a very fine-grained sandstone with limonite ledges and silicified wood, yellow and grey mottled. Flood plain deposit recording periodic overbank deposition and periodic flood episodes. Channel migration toward area. Soil formation in upper portion. Shale; medium grey, fissle, silty, with rare siltstone interbeds, coarsens upward to siltstone, grades into next unit. Flood plain deposit recording channel migration toward area. LOWER CRETACEOUS (ALBIAN) PATAPSCO FORMATION Fig. 4 -- Geologic section of the rocks exposed at the east terminus of Jackson Street, one mile south of Bladensburg, Maryland (Stop 2). Section measured by Leo J. Hickey and Norman Frederiksen, 1984. For key to symbols see Fig. 2.