THE CATSKILL GEOLOGISTS BY PROFESSORS ROBERT AND JOHANNA TITUS - Years and Rocks

All through our Catskills are endless exposures of sedimentary rocks. When the two of us find ourselves approaching one of them we always have a bunch of questions to ask. Our first ponderings ask what kind of environments produced those sediments? Had this once been the bottom of an ocean? Had it been a deep sea or a shallow one? Was this dry land? If so then what kind of climate had prevailed? Was it a lake on that dry land? Were these sediments once windblown sands? On it goes. Then there is an altogether different sort of question: how many years had passed by while those sediments were being deposited? Had it been decades, centuries, millennia or even millions of years? There are so many possible answers to all these questions. Our job is to answer as many of them as possible. It might be work but we think it is fun work.

That issue of time is always a fascinating one. Typically, people tend to overestimate the numbers. It’s fun to look over an outcrop from bottom to top and imagine millions and millions of years. But that is commonly just plain wrong. Let’s speculate about geologic time in today’s column. We will be forced to speculate a lot but that’s okay – sometimes. 

Take a look at our illustration, courtesy of the Paleontological Research Institute in Ithaca.  It’s from an important new set of books by our friend Dr. Charles “Chuck” Ver Straeten who is an active researcher at the New York State Museum. Geologists call this sort of thing a stratigraphic column. It’s, as you can see, a column and its stratigraphy portrays all the sedimentary rocks of the Catskills. The blues at the bottom are limestones. The red strata are sandstones, and they grade into the heavily dotted yellows at the top which are petrified gravels called conglomerates. All this portrays the deposition of the Catskill sequence from the early to the late Devonian Time Period. That’s about 7,750 feet of strata deposited during about 42 million years. That works out to approximately 450 years of time per inch of deposition. Go out and find a nearby outcrop and eyeball and estimate of how long it might have taken to deposit those strata. Yep, that’s lot of time!

But there are a lot of problems with that estimate. It’s only an average and over long periods of time there are episodes of rapid and slow deposition. Then too, there are times when no deposition occurs at all. When you think about it, there isn’t very much hard knowledge that comes out of this sort of averaging. Let’s take a good look at an example. See our other illustration. That’s a photo sent to us by some of our readers from Andes. It’s a real typical Catskill boulder. It looks about 8 feet from bottom to top. If we accept an estimate of 450 years per inch then we are looking at about 43,000 years of time. Maybe.

But look at those three heavy black lines that we have added. They divide the sequence into four packages. Each represents a single moment of time; each one is a single flooding event. Those were probably important – even massive flood events – but how long does a flood last? The answer to that is usually just a day or two.

So, there you have it. We are justified in claiming that we are looking at about 43,000 years of time. That’s almost 16 million days. But perhaps only eight of those days came to be preserved in the rock record. All the others were lost to time; they are represented by just those three black lines. That’s a lot of missing time. We know almost nothing about it but we can ponder it. Trees came and went, and so too did forests. Vast numbers of animals wandered through all these forested landscapes. Endless numbers of full lives passed by. Animals were born and grew from infancy to adulthood. They often had full happy days and knew the joys of life, and then bad ones came by as well. There was a lot of history here. But none of this was preserved in the strata.

Look out the nearest window. There’s a lot going on out there, isn’t there? But will any of it leave any kind of history millions or hundreds of years from now. Fat chance!

Contact the authors at randjtitus@prodigy.net. Join their facebook page “The Catskill Geologist.” Read their blogs at “thecatskillgeologist.com.”