Last week we visited the pocket beach along the shore of the Hudson at the Willows. Actually, we just looked down on it. This week let’s go down and look around. There is a lot to see and think about when you are interested in exploring the geology that’s there. On our visit we happened to get there just as the tide was going out. Yep - the tide; the Hudson is a tidal estuary all the way north to past Albany. Take a look at our photo which looks south from the Willows beach. That’s the Rip Van Winkle Bridge in the far distance. The foreground shows wet land, just exposed by the receding tide. That makes it something that geologists call a tidal flat. Scattered across the surface is a litter of tidal debris, almost all of it is vegetation. Offshore a short distance are breaking waves. Just in front of us, especially to the left, if you look carefully, are wave-rippled sands. The beach sediments were sculpted into those ripples by the recent high tide’s waves.
There’s a story here. Perhaps an hour before we got there, it was a full high tide. The waves were breaking in what would have been right in front of us. They had approached the shoreline here relatively rapidly. That carried a little of that beach sediment and that’s when the waves sculpted that material into those ripples. There was a flotsam of vegetation too, a mix of branches grading down to a lot of small twigs. As the tide reached its peak, the flow settled down to a stillstand. All the vegetation and the rippled sediment settled onto the beach. Just a little time passed by in this, the highest moment of the tide. Soon came the ebb and the water began draining away. It should be that all that sediment and all the vegetation would be carried off. Low tide should reverse all the effects of high tide. Right? Nope, wrong. You see, the very first flow of the ebb tide is so slow that it cannot pick up any of that high tide flotsam. It’s left behind; all the branches and all of the rippled sediment are left stranded. So, there is something of a depositional one-way street here. The rising tides bring sediment and debris onto the beach, but the low tides are largely unable to remove it. That’s essentially what creates a beach; that’s what we found at this one.
As is so often the case, we have been once again hoping to help develop your trained eyes. When you come to the Willows beach or any other, we hope you will know how to seek out the kinds of things that we see. Watch for ripples and the sedimentary material. See the dynamics of a very active shoreline environment. But mostly, we hope that you will be learning to look and see with a real understanding of what is right in front of you.
Contact the authors at randjtitus@prodigy.net. Join their facebook page “The Catskill Geologist.” Read their blogs at “thecatskillgeologist.com.”
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