Historic Background
Peat cores taken in and around Sybil Creek marshes (this study) have shown that this area of the Branford River watershed has been under tidal influence for about the last two to three thousand years (most peats extend less than two and a half meters in depth to Holocene sands). During this time, the marshes above and below Rt 146 were dominated by salt marsh and salt meadow cordgrass with spikegrass (Distichlis spicata) and a variety of forbs mixed in the community. With the exception of salt meadow cordgrass harvesting, some minor dredging and filling along the upper borders and the installation of mosquito control ditches on the marsh in the earlier part of the 20th Century, the system below Rt 146 has remained relatively unchanged for the last few millennia (there is more high marsh vegetation today).

The marsh areas above Rt 146 (referred as Central, North and East Marsh in Milone and Macbroom 1996; Fig 1) have experienced a very different pattern of development during the last few centuries. Although Rt 146 has been a thorough fare since Colonial times, it wasn't until the earlier part of the 20th Century that the road was fitted with tide gates thus severely limiting tidal hydrology. For this reason we only see common reed as a very minor component of the upper border community (Orson 1999). It isn't until the last 75 years that reed became a dominant species.

Photograph #1: View of one-way flapper tide gates along Rt. 146. Gate to the left does not seat properly and minor tidal fluctuations occur upstream.

The installation of the tide gates (Photo #1) was not the first major disturbance to these marshes. The areas directly above Rt 146 that parallel Waverly Park Rd (Central and North Marsh) were extensively filled during the mid to late 1800s to lay bedding for the installation of a trolley line that ran to the shoreline community. Peat cores taken in this area show about 35 cm of new marsh peat have developed over two meters of mud fill. Within this top 35 cm of peat, there are a few horizons worth noting. The portion of the peat that sits directly on top of the mud fill (ca. 35 cm to 20 cm) is dominated by salt marsh peats. At about 20 cm, there is a change in the structure of the peat becoming more friable. Between 15 and 10 cm in depth the first true reed peat signature becomes identifiable. Since we know that the trolley line was installed during the mid 1800s, the development of salt marsh peat above the fill had to have occurred after about 1850 or so. We also know that tidal flow was eliminated from the area by about 1920 and that it took a few decades for reedgrass to establish itself (several homeowners who have lived on the marsh for over 50 years insist that the dominance of reedgrass is a relatively recent occurrence that has occurred within their time in the area). Therefore, the lower 15 to 20 cm of peat sitting directly on top of the trolley fill represents the development sequence between ca. 1850 and 1920. The changes in peat structure at about 20 cm represents the period of tidal restriction and the accumulation of reed peat from about 15 cm to the surface indicates the accumulation of reedgrass in this system since the late ca. 1940s or early 1950s.

The areas above Rt 146 that are removed from the trolley line (the East Marsh) show salt marsh peats (dominated by tightly woven roots and rhizomes of cordgrass grasses) extending downward to about two meters. It is only within the top ten to twenty centimeters that we see brackish peats developing. These brackish peats contain either reedgrass and/or forbs or cordgrasses indicative of brackish water conditions (friable structure, increase in hummocks, increase in size of salt meadow cordgrass rhizomes with a concurrent decrease in density of woven peat) that have existed in this system since the installation of the tide gates.