Data from Mortimer 1987                  

Despite recent research pertaining to Lake Erie's erosion and sedimentation rates, little is known about the sedimentation processes occurring in Long Point's Inner and Outer Bays. Longshore drift carries a portion of Lake Erie's sediments from east and west of Long Point and deposits an unknown amount of the load into the Bay. While the amount and quality of sediment that reaches the Bay from this source is poorly understood, the majority of this sediment is probably deposited offshore as well as into the Outer Bay (Downey et al. 1994).

The limited amount of alongshore and offshore sediment that appears to be settling in the Inner Bay can be attributed to three factors. First, the Long Point peninsula acts as a barrier to the majority of the sediments that are being transported from west to east. Second, limited sources of coastal sediment east of Long Point, relative to areas west of Long Point, result in reduced alongshore sediment transport deposition into the Inner Bay. Third, the presence of a submerged offshore bar between Turkey Point and Pottohawk Point on Long Point creates a barrier to strong current and wave activity, and inhibits the transport of alongshore and offshore sediments into the Inner Bay.

Although the Long Point spit and barrier bar limit external sources of sediment entering the Bay, the protected environment that they create in turn limits water circulation, and consequently, probably causes substantial portions of Big Creek's sediments to settle in Big Creek Marsh and the Inner Bay. It has been suggested that Big Creek provides the major source of sediments that settle in the Inner Bay (Ongley 1974; Philpott Ltd 1989; Lawrence and Nelson 1994). However, while Big Creek carries 77,000 tons of solids into the Big Creek Marsh and Inner Bay annually, the exact amount of sediment that is deposited into the Inner Bay is unknown (Lawrence and Nelson 1994). This uncertainty can be attributed to our limited understanding of water currents and water exchange between Big Creek Marsh, the Inner Bay and the Outer Bay. It is, however, known that those sediments and nutrients that do enter the Bay via Big Creek play an important role in the Bay's succession (i.e. changes in plant communities over time)(Berst and McCrimmon 1966). The trapping of sediments (as well as nutrients) by the causeway has also had a strong influence on the Big Creek Marsh as wetlands west of the causeway are much more extensive today than they were before causeway development.

The quality and quantity of sediments that enter Big Creek Marsh and the Inner Bay are dependent on soil characteristics and man's influence on landscape structure within the Big Creek watershed. Throughout the Lake Erie watershed, bedrock is generally covered to considerable depth with late-glacial freshwater sands and clays (Ongley 1974). In contrast to the clay soils to the east, the soil of the Big Creek drainage basin is primarily an undulating sandy loam (Figure 3.1)(Webber and Hoffman 1967). This sand plain is well drained, and being highly productive, supports a large tobacco and cereal grain industry (Chapter 9; Heathcote 1981). Due to the decreased tendency for surface flow relative to clay, and the decreased capacity of a stream with increasing particle size, a river system draining coarse-grained sediments (e.g. sand) will presumably carry a reduced suspended load than one draining fine deposits (Ongley 1974). However, while Big Creek does have a lower suspended and dissolved sediment load (per unit area of watershed) than most of Lake Erie's tributaries, it does in fact contribute a substantial portion of Lake Erie's suspended load, all of which enters Big Creek Marsh and the Inner Bay (Table 3.2). Also, Big Creek has a high bedload of sand that rolls along its bottom and probably further contributes to the sedimentation of Big Creek Marsh and Long Point Bay.