Geology topics

Jeffrey G. Paine

Publications and source records attributed to Jeffrey G. Paine.

3 recordsLinked to original sources

USGS2026

Matagorda Formation—A new Holocene coastal stratigraphic unit, Texas

We propose and describe the Matagorda Formation, a new stratigraphic unit comprising Holocene coastal (sea-level influenced) deposits on the Texas coastal plain. This formation consists of sediments deposited in fluvial-deltaic, bay and bay-margin, and gulf-margin paralic environments since the last glacial maximum (marine oxygen isotope stage 2, or MIS 2) within and at the margins of stream valleys incised into the coastal plain since the last Pleistocene sea-level highstand during MIS 5. The Matagorda Formation includes informal coastal facies that are influenced by sea level and grouped into fluvial-deltaic deposits (Lavaca Member), bay and bay-margin deposits (Carancahua Member), and paralic gulf-margin deposits (Saluria Member). Other coastal facies, such as eolian sand or silt sheets and clay dunes, are included in the Matagorda Formation but are not included within the members. The type area is herein defined as the Matagorda Bay system on the central Texas coast, where many examples of facies within the proposed formation are exposed along and near the shoreline. The upper boundary of the Matagorda Formation is the active depositional or erosional surface either on land or at the water bottom beneath coastal streams, tidal channels, and bays. The lower boundary is a composite unconformity that may be marked by (1) a mature soil or erosional surface at the top of the Pleistocene Beaumont Formation (a sharp boundary with or without soil development below the unconformity), (2) the top of alluvial terrace deposits above the Beaumont Formation (Deweyville Formation or broad equivalent) within the incised valley (sharp boundary with or without soil development below the unconformity), or (3) fluvial deposits above the Beaumont Formation at the base of the incised valley that predate the Holocene transgression (possibly a gradational boundary where active deposition was occurring as sea level rose and base level reached the incised valley).

Professional Paper↗

USGS2000

Responses of stable bay-margin and barrier-island systems to Holocene sea-level highstands, western Gulf of Mexico

The microtidal, wave-dominated coast of the western Gulf of Mexico displays a variety of Holocene geomorphic features indicating higher-than-present water levels that were previously attributed to storm processes while geoidal sea level was at its present position. Field and aerial-photograph examinations of bay margins, barrier islands, and beach-ridge plains following major hurricanes show that the elevated features are inundated periodically by high storm surge. Despite their inundation, these highstand features are not modified by modern storm processes. Instead, storm-related erosion and deposition are always seaward of and lower than the highstand features and are always limited to the extant shorezone, where elevations typically are less than 1.5 m above present sea level. Bay-margin and lagoonal highstand indicators include raised marshes and subtidal flats, wave-cut benches, abandoned wave-cut scarps with fringing marshes and/or beach ridges, and accretionary islands and recurved spits. Other emergent marine features include abandoned compound flood-tidal delta and washover fan complexes attached to barrier islands and anomalously high beach ridges within both the barrier-island complexes and beach-ridge plains. The highest beach ridges, raised marshes and flats, and erosional scarps and benches are manifestations of one or more rising phases and highstands in sea level, whereas the lower marshes and accretionary topography are mainly products of the falling phases and shoreface adjustment to present sea level. Different elevations of beach-ridge sets, discordant truncation of beach ridges, and elevated marine- and brackish-water faunal assemblages preserved in beach ridges, raised marshes and flats, and natural levees are compelling evidence of sea-level fluctuations of ±1 to 1.5 m from about 5500 to 1200 cal yr BP. Independent evidence from studies of geodynamic, climatic, and glacio-eustatic processes can explain the mid-Holocene highstands and late Holocene lowering of sea level that is observed in tectonically stable coastal regions far from former centers of glaciation.

Journal of Sedimentary Research↗

USGS1993

Monitoring beach changes using GPS surveying techniques

A need exists for frequent and prompt updating of shoreline positions, rates of shoreline movement, and volumetric nearshore changes. To effectively monitor and predict these beach changes, accurate measurements of beach morphology incorporating both shore-parallel and shore-normal transects are required. Although it is possible to monitor beach dynamics using land-based surveying methods, it is generally not practical to collect data of sufficient density and resolution to satisfy a three-dimensional beach-change model of long segments of the coast. The challenge to coastal scientists is to devise new beach monitoring methods that address these needs and are rapid, reliable, relatively inexpensive, and maintain or improve measurement accuracy. The adaptation of Global Positioning System (GPS) surveying techniques to beach monitoring activities is a promising response to this challenge. An experiment that employed both GPS and conventional beach surveying was conducted, and a new beach monitoring method employing kinematic GPS surveys was devised. This new method involves the collection of precise shore-parallel and shore-normal GPS positions from a moving vehicle so that an accurate two-dimensional beach surface can be generated. Results show that the GPS measurements agree with conventional shore-normal surveys at the 1 cm level, and repeated GPS measurements employing the moving vehicle demonstrate a precision of better than 1 cm. In addition, the nearly continuous sampling and increased resolution provided by the GPS surveying technique reveals alongshore changes in beach morphology that are undetected by conventional shore-normal profiles. The application of GPS surveying techniques combined with the refinement of appropriate methods for data collection and analysis provides a better understanding of beach changes, sediment transport, and storm impacts.

Journal of Coastal Research↗