Published examples of conglomeratic sandstone shorelines are extremely rare. Two different middle to late Eocene facies sequences reflect variable proximity to sediment influx and high-energy domination. Storm-generated deposition predominated away from fan-delta input. A tripartite coarsening-upward transition represents an offshore to shoreface succession. The lowermost mudstone contains graded rhythmites, starved ripples, flame structures, and bioturbated zones, indicating alternating low- and high-energy offshore deposition. Overlying sheet sandstones thicken and amalgamate upward, denoting shallowing and increased storm deposition still below fair-weather wave base. These beds contain a basal lag overlain by planar laminae, then hummocky cross-stratification, and finally wave-ripple laminae. Coarse-grained, cross-stratified, upper-shoreface sandstone caps the seqeunce.
In contrast, sedimentation associated with subaerial flooding dominated a coarsening-upward sequence seaward of and truncated by an alluvial fan. Tbce turbidites characterize offshore deposition below fair-weather wave base. Thick climbing-ripple intervals and intervening unburrowed rhythmites indicate high sedimentation and/or freshwater influx. The overlying fine-grained, planar-laminated, lower-shoreface sandstone also lacks bioturbation and contains isolated cobbles surrounded by scours. An enigmatic succession of lensoid sandstone bodies, each 2 to 10 m wide and draped by mudstone, caps this sequence. Upper surfaces of these antiformal beds create a swell-and-swale topography. Internally, planar laminae pass upward to trough cross-stratification, then an upper organic-rich, muddy zone with Ophiomorpha and Gyrolithes burrows. Subaqueous channeling and/or bar formation in front of the fan delta, with intervening quiescent periods, are suggested.
