This paper is a case history of coastal development at Camp Ellis, Saco, Maine. It begins in 1867 with dredging and jetty construction at the mouth of the Saco River to facilitate commercial navigation. Beach accretion, resulting from tidal delta collapse, was followed by residential development before the ephemeral nature of the shoreline was recognized. A misunderstanding of the riverine source of beach sand and the net, northward direction of longshore transport confounded U.S. Army Corps of Engineers (USACOE) efforts to maintain navigation and the adjacent beach. Beach erosion at Camp Ellis claimed dozens of properties before the role of the north jetty at the mouth of the Saco River became apparent to state and university scientists. Erosion also led to sand migration to the north and to the closure of the Little River inlet and growth of Pine Point spit. This spit was later developed and a jetty was placed at its tip to preclude continued accretion into the Scarborough River inlet. Despite numerous studies, the USACOE failed to recognize the connection between beach erosion at Camp Ellis and beach accretion at Pine Point. Under political pressure, the USACOE recently conducted detailed modeling studies and has proposed construction of breakwaters seaward of Camp Ellis to solve the problem. A discussion of the pros and cons of this proposal is presented in light of the long history of development at Camp Ellis.

Duxbury Beach, Massachusetts, is a retreating, transgressive barrier that is effectively managed to meet a range of competing land uses. While the barrier is heralded as a natural coastal setting, the entire landform is methodically engineered on an ongoing basis to best accomplish the goals established for the beach within a context of natural processes. Historical and geological data indicate that the natural barrier form includes numerous ephemeral tidal inlets (some of which have migrated) and overwash channels, and low discontinuous dunes. At present, the managed barrier has a continuous vegetated foredune and broad backdune. Management techniques have evolved over the past several decades based on growing experience and understanding of the coastal processes and of wildlife habitats. Although the foredune crest is reconstructed each spring, the entire beach is gradually being allowed to retreat to remain in equilibrium with rising sea level. The lagoonal shore is being widened through beach nourishment and through proposed creation of back-barrier salt marshes using silty dredge spoil. Uses of the barrier include town and public recreational beaches, off-road vehicle access, a right-of-way to isolated communities, flood protection of landward areas, and shorebird nesting habitat.

Abstract Protected tidal inlets in four estuaries along 100 km of the south-central Oregon coast contain tidal-marsh stratigraphic sequences that suggest different styles of relative sea-level rise during the late Holocene. The south-central coast lies 70 to 90 km east of the leading edge of the overriding North America plate in the central part of the Cascadia subduction zone. Localized differences in the style of submergence along this actively deforming coast imply differences in the rate and extent of coastal subsidence or uplift during subduction of the Juan de Fuca plate beneath the North America plate. Thick tidal-marsh peat in the northern part of the study area records gradual submergence (1.0-1.6 mm/yr since 2.0-2.5 ka) that rules out large (>0.5 m), sudden changes in relative sea level, such as have occurred along other subduction-zone coasts during some historic great earthquakes (magnitude>8). In the south part of the study area, changes in intertidal lithofacies across abrupt transgressive and regressive overlap boundaries are consistent with localized coseismic subsidence and uplift of about 0.5 to 1.0 m above faults and folds in the accretionary wedge of the North America plate. Most coseismic deformation on these local structures probably coincides with great subduction earthquakes, but some localized deformation may reflect much smaller earthquakes that occur independently of plate-boundary events.

Abstract This lecture course is designed to provide geologic insights towards the development of depositional and exploration models for sandstone reservoirs associated with one or more of a variety of shelf and shoreline environmental settings. Sedimentologic and stratigraphic criteria will be utilized to more accurately predict the subsurface distribution and trend of reservoir quality sandstones. These criteria include a number of basic geologic “tools” such as well logs, cores, outcrop, seismic, and isopach and structure maps, all of which will be utilized in varying degrees during this course. Equally important in the development of models for shelf and shoreline sandstones is the subsurface analysis of modern depositional systems. An understanding of the three dimensional framework of modern clastic sedimentary environments is critical to the proper interpretation of vertical sequences, lateral facies relationships, sand body geometries and inhomogeneities of sandstone reservoirs.