A computer program has been written to overcome the limitations of two published programs that compute statistical parameters in grain size analysis. This program uses all available data, obtained from standard sedimentological analyses, regardless of phi interval, and computes statistical parameters by direct integration of a linear approximation to the cumulative curve. This has the advantage that the distribution curve is known and hence the limitations of the parameters obtained can be assessed. Furthermore, it is argued, with examples, that this approximation introduces no greater degree of inaccuracy than is already present in standard sampling and analytical procedures.
New evidence invalidates the former concept that Pleistocene shorelines are "terrace" cut and fill structures. Comparison of Pleistocene and Holocene sediments with morpholo gy of the shoreline indicates that Pleisto cene deposits accumulated in barrier island environments and that the "ter races" are former lagoon-salt marshes. Stratigraphic evidence supports six ma jor Pleistocene shorelines below an elevation of 100 feet (30 meters).
An inter-disciplinary study has been undertaken in Start Bay, Devon. Geophysical data show that infilled channels dissect the bedrock surface of the Bay shoreward of a buried cliffline. Beyond this feature the surface resembles an abrasion platform. The three lithological units within superficial material are referred to as
barrier, bay
and
bank
deposits, Foraminiferal and sedimentological evidence, together with C-14 dates, indicate that a barrier-lagoon complex has migrated to its present position in response to oscillations of sea level during the latter stages of the Flandrian transgression. Analysis of vibrocore and other samples shows that wave and current processes are variously dominant in the upper 2 m of the superficial deposits. The relative stability of the Skerries Bank may be explained by the values of the residual currents which approach zero along its crest. Water particle velocities nearshore off Slapton Beach suggest that short period edge waves are responsible for shoreline cusps observed in the Bay. While experiments with tracer material indicate that longshore movement may variously depend on linear dimension, ratio or shape index, no clear relationship has been established with nearshore wave parameters. Evidence suggests that Start Bay is a
closed system
under present-day conditions, there being no nourishment of the foreshore from outside the area. The 1917 Hallsands disaster can be attributed to the legacy of dredging shingle from the intertidal zone between 1897 and 1902, combined with a critical combination of storm waves, gales and spring tides.
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