Last week we visited the Willows, a late 18th Century farmhouse along the Hudson River, south of Athens. We found the old farm to have been developed on fertile soils which, in turn, developed from the sediments of Glacial Lake Albany. This week let’s go exploring the Willows’ property and start seeing what other geological features might be seen there. There is an extensive trail system at the Willows. See the map they have produced. We started out at the house itself and headed to the southeast on the Red Trail. That took us down a relatively gentle slope toward the river. Soon we noticed a shallow canyon to our right. Surprisingly, there was no water in it. There had been some recent rain but not enough to generate or even sustain a stream. The floor of the canyon lay above the water table, so, of course there was no stream here. But how could a canyon be present when there is no stream in it? Good question! This is what geologists call an intermittent stream. It’s seasonal, only active for a short period of time during the rainiest time of the year and perhaps even only during the rainiest years. When it does rain enough then the flow is seen, but it does not last for long. That’s the “intermittent” part of the story.
We were seeing something that we would see again a number of times on our hike. We found our way to the Yellow Trail and hiked north. We would find at least five intermittent streams along the way. See our second photo for the one we liked the most, well to the north. We had found a pattern; much of the post glacial geological history at the Willows was one of intermittent stream formation. What had been going on? When we got down to the bottom of that first one, we saw that it was pretty big and pretty wide. That suggested that there had once been a time of much higher streamflow. Continuous, not seasonal, flow may well have eroded this, the lower part of the canyon. Our hypothesis had taken us back to very late in the Ice Age when a warming climate had produced large flows of eroding waters. But we just weren’t entirely sure that we were right. Our second hypothesis was that this was simply the product of long periods of minor intermittent flow. Which hypothesis is right? How exactly had these channels formed? We just haven’t decided yet. That’s typical of how the scientific method works; it takes time to work out such solutions. Go and look for yourself and see what you think.
In the end, we are introducing one of those geological terms that you should know: the intermittent stream. They are common all over the place, wherever you are likely to travel, and you should become aware of them. From now on, you should be able to spot them when you see them. You should know what they are and understand how they formed. There, you are just a bit smarter than you were five minutes ago.
Contact the authors at randjtitus@prodigy.net. Join their facebook page “The Catskill Geologist.” Read their blogs at “thecatskillgeologist.com.
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