“Ramp and Pluck” — The Catskill Geologists
The Mountain Eagle; Jan. 26, 2018
Robert and Johanne Titus
We have been nosing around, looking for geological features that work well in the winter. Last week we found an impressive view of Glacial Lake Schoharie, an image of that old lake that positively shined in the winter snow. That was on Rte. 145, just west of Middleburgh. Just a few minutes later, on the same drive, we stopped and took a good look at Vroman’s Nose, just east and again on Rte. 145. We noticed something we had not seen before. That’s this week’s column.
Take a good look at our photo. It’s a cross section view of the Nose; it’s the best view you can obtain. It show’s all the structure of what is called “ramp and pluck” topography. Notice that the right (north) flank of the mountain tapers off gently; its slope is relatively low. The left (south) flank, however, is far steeper. All this reflects the behavior of the glacier that once passed across the Nose.
That was the Schoharie Creek Valley glacier. It moved right to left, or north to south in our photo. The ice scoured its way up the north-facing ramp of the mountain. Then the ice passed across the crest of the mountain and soon it yanked, or plucked, an enormous mass of rock right out of the south side. That’s the south facing cliff. Well, hence the name ramp and pluck. It’s a very descriptive term, an unusually good choice of words for science.
Well, we already knew all this; we have been here so many times before. But on this visit, there was something different. It was in the snow. Notice the nice thick blanket of snow on the ramp side. Then see how the snow is nearly absent from the darker, steeper south facing slope. The plucked slope is a virtual cliff. Snow can accumulate on the ramp side but it cannot on the plucked cliff. The two sides stand out in sharp contrast, thanks to the snow.
None of this is terribly important; you won’t find anything like this discussed in a glacial geology textbook. But it is an aesthetic; isn’t it? And it helps train the eye, doesn’t it? And perhaps that does add some “importance” to what we are talking about. Geology is an experiential science; it is widely said that the best geologist is the one who has seen the most rocks. But, also, perhaps it is the best geologist who has seen the most rocks in the best way!
And that is the point here. We seem to have found a new way to look at geology in this season of the snow, and that new way is likely to offer insights as we continue our explorations. We intend to devote ourselves to noticing more winter images of this sort; there may be other interesting snowbound features out there.
But, in the meantime, it is training your eyes that we are interested in today. Ramp and pluck topography is important and common. Perhaps this is the time of the year when we should be looking for it. Perhaps you can keep out a sharp eye too.
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