An eddy forms on the upstream side of the junction of the Cold and Deerfield rivers, aided in part by large woody debris that has piled up there. The log jam deflects flows from a side channel of the Deerfield. This slows the water down and allows sediments to drop out, creating a bar between the Cold and the Deerfield.
The trees seen across the channel are on a small island in the Deerfield, with the Deerfield’s far shore showing to the center and right of the bottom image, where eroded banks are seen.
Sediment and large woody debris deposited at the junction of the Cold and Deerfield rivers. Some of the sediments come from the Cold River, a high-gradient stream. When flows reach the Deerfield, they are apt to slow down, dropping out materials and forming a delta. Due to the influence of upstream dams, the Deerfield is likely to carry a lighter sediment load than the Cold River in most situations.
Much of the sediment at this location consist of fine sands and silt.
As these images show, the deposits are stable enough to support a variety of vegetation, from grasses to trees. A colony of Japanese Knotweed, an invasive species, has established itself at this spot. Floods are suspected to aid in the distribution of invasive species.
These images show the other side of the deposits that have been formed at the junction of the Cold and Deerfield. While sediment depostion was the dominant processs on the Deerfield side, a mix of deposition (of some rather large materials) and erosion can be seen on this side.
Before Tropical Storm Irene, the Cold River emptied into the Deerfield just a few yards from Route 2. The high flows and debris load of Irene altered the course of the river, shifting it some 70 yards west. In its new course, it carved into the island, removing a good chunk of it. The debris field left by this realignment, with many large boulders visible, suggests the power of the flows generated by Irene.
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