The purpose of this study was to examine the coastal geomorphology of Gouldsboro Bay as a preliminary step in investigating the late Quaternary development of this area. Coastal Gulf of Maine waters are characterized by a wide summer temperature range (Apollonio, 1979).
BATHYMETRY OF GOULDSBORO BAY
The maximum depth of the bay is 29 m at the mouth in the channel between the two Sally Islands. Because of the general east-west orientation of the Outer Banks in the Gouldsboro area, the only available wave approaches are from the southern quadrants.
OLD TOWN 1960 - 1964
Investigation of the study area by aerial reconnaissance, in which the entire area was documented with oblique aerial photography. Characterization of the station by establishing permanent intertidal profiles using a technique modified from Emery (1961).
INTERTIDAL PROFILES
Geomorphology of the High-Intertidal Region In the Gouldsboro Bay complex, four high-interval geomorphic features are present. Geomorphic features found in high intertidal regions are pocket beach, linear-margin beach, exposed reef, and marsh.
IDEAL
INTERTIDAL PROFILE
POCKET BEACHES
Sand Gravel
Gravel: Gravel bag beaches make up 43.8% of all bag beaches and 3.9% of the total high intertidal coastline of the study area. Mixed: Mixed pocket beaches account for 44.9% of all pocket beaches and 3.9% of the total high intertidal shoreline.
GBP-4
50 60 METERS
2 _ GBP-7
GBP-5
DISTANCE IN
METERS
T he incidence of fringing beaches is high in the central and upper parts of the main bay and decreases towards the bottom (Figure 14). T he lower two-thirds of the beach has a gentler slope and consists of a flattened pavement of sand and gravel. It is clear that the upper part of this profile is erosion due to the number of uprooted and toppled trees found on the cliff crest and slope (Figure 15).
The cut and dip at the base of the bluff indicates that significant erosion is occurring. Exposed bedrock shoreline in the study area is quite abundant, as it is along most of the Maine coast. Because of its location in the eastern part of the island-bay igneous complex, the extant bedrock is uniform in composition (silicic and intermediate) and form (massive) (Chapman, 1962a).
This uniformity is in direct contrast to bays that are structurally and compositionally more complex, such as French Bay, located to the west of the study area (Figure 1). With the exception of the outer Sally Islands and the lower bay, the control of shoreline geometry by rock structure and composition is minimal in the Gouldsboro Bay area.
Sd313W NI N0IIVA313
Low Slope: The low slope shoreline represents 42.9% of all exposed bedrock and 16.5% of the total high intertidal shoreline of the study area. To be classified as a low-slope coast, the high-intertidal relief does not exceed two meters, the total slope of the bedrock along the profile is less than five degrees, and the low-slope terrace is wide (often hundreds of meters). Although a permanent profile was not established, this station illustrates all the characteristics of a low gradient (Figure 18).
1% of all exposed bedrock and 12.0% of the total shoreline at high intertidal areas of the Gouldsboro area. The only correlation between intermediate slope distribution and lithology occurs at the entrance to the main bay. There is a high abundance of moderately sloped shoreline at the mouth of the bay (Figure 16), consistent with a biotite and biotite-muscovite granite terrain (Figure 7).
A moderately sloped shoreline is commonly found throughout the rest of the Gouldsboro area, especially in the West/Grand Marsh Bay complex, but its distribution is not consistent with the coarse lithology. An example of the first variant is found near the bay mouth on the east coast (GBP-8 in Figure 8).
MHW (?)
GBP-8
To be classified as a steep slope coastline, the high intertidal relief is more than three meters, the dip of the rock is greater than 15°, and. T he choice of a 15° slope for the separation between intermediate and steep slope is based on the width of the low water terrace. T he profile station illustrating steep slope coastline is located near the mouth of the lower main bay on the western shore (GBP-9 on Figure 8).
The overall slope of the high intertidal region averages 17°, but along the upper part of the profile the slope is much steeper due to the blocky structural nature of the bedrock (Figure 20). This accounts for 13.2% of all marsh deposits and 6.9% of the shoreline with high tidal inlets when both are measured. The characteristics that characterize a mature bog are as follows: (1) existence in large funnel-shaped fens; (2) frequent meandering tidal channels and tributaries with little freshwater input; (3) clear zonation of vegetation; (4) numerous salt pans and "rotten spots" (Chapman, 1960) on the high marsh surface; and (5) a narrow tidal channel compared to the total width of the swamp.
Similar in distribution to the mature-type marsh, brackish is found only in protected areas of tidal tributary bays. The distinguishing characteristics of a brackish marsh are as follows: (1) a location along narrow channels connecting freshwater streams with tributary bays; (2) straight tidal channels with few branches; (3) poor vegetation area; (4) no salt or "rotten" spots on the surface of the marsh; and (5) a wide tidal channel relative to the overall width of the marsh surface (equally
GBP-3
GBP-9
MARSHES
36 SMITHSONIAN CONTRIBUTIONS TO THE MARINE SCIENCES . than half the total marsh width at its seaward edge). The profile station characterizing brackish marsh is located in Timber Cove between West Bay and the main bay (WBP-2 on Figure 8). Surrounding: Surrounding marsh accounts for 66.1 % of all marsh deposits and 34.6 of the total high-intertidal shoreline in the study area.
Fringe marsh is the dominant littoral type in all three tributaries, but is present in the main bay, particularly on the eastern shore at the top of sheltered coves (Figure 21). Characteristically, a marginal marsh (1) exists as a narrow strip parallel to the coast that rarely exceeds a width of five metres; (2) have little or no zonation of vegetation;. An example of primary fringing marsh is found at the top of a deeply incised cove on the northeastern shore of the main bay (GBP-6 on Figure 8).
This profile station shows a small but lush marsh deposit in the high intertidal zone (Figure 24). A profile station illustrating a secondary marsh is located on the central west shore of West Bay (WBP-1 in Figure 8).
WBP-1
In the study area, approximately one-third of the surface of the entire bay complex consists of geomorphic features from the low-tidal area. Mudflats cover 54.8% of the area in the low-tidal zone of the Gouldsboro Bay complex. S A N D / R O C K FLAT. – Mixed sand and rock flats constitute only 3.6% of the surface area in the low tidal zone of the study area.
In the studied area, the rock bed represents 5.2% of the surface coverage in the low tide zone. SHELL.— Shellfish occupy only 1.3% of the area in the low-tidal zone of the study area. This geomorphic feature is located mainly in the center of the more sheltered tributary bays (Figure 27).
Another sign of faulting in the middle gulf is evident in the distribution of bluffs (cut moraines) bordering the gulf coast (Figure 36). The abundance of these elements in the upper part of the main bay and in the tribu-.
ORIENTATION OF GLACIAL STRIATIONS IN BEDROCK
These conditions are the bathymetry of the main bay, the characteristics of the subtidal bottom sediments, the benthic infaunal communities and the structure of the sub-bottom bay. The texture of the subtidal bottom sediments also changes abruptly across the central bay (Figure 38). Finally, the most significant difference between the upper and lower parts of the main bay is the dramatic change in the structure of the subbed across the middle bay.
A seismic profile of the subfloor along the longitudinal axis of the main gulf reveals an abrupt change across the mid-gulf fault (Figure 40). A shallow surface later interpreted as a subtidal expression of the Dyer Neck Moraine (Fig. 40) marking the beginning of a shoal (break) in the middle bay. Pebble beaches are found near the mouth of the bay (open to ocean waves) or on the west coast in the center of the main bay (open to storm waves from the "northeast").
Intermediate in terms of wave energy, mixed pocket beaches are located in some abundance in the lower half of the main bay (eastern and western shores) and on the southeastern shore of the upper main bay shoreline. Lobster Cove is one of the deeply incised bays located on the lower eastern shore (Figure 2).
TYPICAL ANNUAL WIND PATTERNS
An example of this relationship can be seen in the differences in the distribution of marshes between the eastern and western shores of the main bay (Figure 21). Due to the high wave energy conditions, gravel is the predominant sediment size class found along the coastline. A secondary feature is the occurrence of well-developed clusters of mussel beds on the flats of the tributary bays.
Therefore, the distribution of these communities is a function of shoreline geomorphology and sedimentology. Detailed mapping of the entire bay complex reveals several striking trends in the distribution of geomorphic features. A sharp mid-bay transition in geomorphology occurs in the middle of the main bay.
A Contribution to the Knowledge of the Origin and Development of Certain Marsh Lands on the New England Coast. Remarks on the Geology of the Coast of Maine, New Hampshire, and T h a t Part of Massachusetts North of Boston.
