WE HAVE BEEN PROGNOSTICATING about how climate change might affect Columbia County over the course of future decades. We have suggested that rising sea levels may raise the level of the Hudson River and that our local climate may become a good bit rainier. We have gone on to suggest that landslide events may become more frequent. Our fear is that heavier rain may soak into our region’s glacial lake deposits and trigger those slides. That would be all the worse if the waters of the Hudson did indeed rise.
But it’s not as if we haven’t already had enough large landslides. We have. The most recent big one struck in February of 2006. It was a slide of glacial lake deposits along the edge of Claverack Creek. That slide occurred very near the Sons and Daughters of Italy Lodge on Bridge Street in the town of Greenport. The clubhouse was located right on the banks of the creek. Right here, that creek flowed through the deposits of Glacial Lake Albany. This was not a particularly deep canyon. It was simply not a dangerous looking location. We suspect that no one ever even imagined that anything like this could happen.
But the year 2005 had seen a relatively rainy fall and winter. The sediments of Lake Albany are likely to have become very soggy. The predictable occurred; the earth gave way and rotated downwards. It was a big slide, measuring about a thousand feet in length along the edge of the river. Fortunately for the Sons and Daughters of Italy, the slide missed their building, but it was a very close call. The slide was a perfect example of a rotational slump. It left a nearly vertical cliff-like “head” right next to the lodge. See our first photo. The downhill “toe” of the slide had flowed into the stream. There were fears that those sediments would dam the creek and cause a flood, but fortunately that did not happen.
This was a classical rotational slump. It followed a rainy season; it represented a curved fracture that opened up within the sticky cohesive sediments of Lake Albany. The slump consisted of earth moving along that fracture in the sediment. it. It was a surprise, but perhaps it shouldn’t have been. The banks of Claverack Creek are well-suited to such slumping. But it is, of course, always a surprise as to exactly when and where such slides occur.
A mile or so to the south, about where Route 23B crosses Claverack Creek, there had previously been another rotational slump. That was the infamous Knickerbocker Cement Plant slide of August 2nd, 1915. The Knickerbocker Plant was a far cry from the Sons and Daughters of Italy Lodge; it was a massive commercial operation. The plant took limestone and converted it into cement. It employed hundreds of workers and occupied a number of large buildings. It was estimated that the cement factory and its supply of limestone weighed a good bit more than 40,000 tons. To make it worse, it rained a lot that summer so the lake sediments must have been quite heavy, even without the limestone.
Except for all of the weight, it was a fairly typical rotational slump. Some 15 acres of land rotated and slumped to the east. The stream was dislocated and literally shoved about 200 feet to the east of where it had been. A boiler broke open and steam, pouring out of it, killed five workers. About 400 people lost their jobs. Repairing the damage cost a quarter million dollars in 1915 money.
In the end, our main point is that projected climate change is likely to make worse geohazards that have long existed in the upper Hudson Basin. We all need to know this.
Contact the authors at randjtitus@prodigy.net. Join their facebook page “The Catskill Geologist.” Read their blogs at “thecatskillgeologist.com.”
