Deep Time (repeated optional content)

[Text on Screen: What is Deep Time?]

Dr. Richard B. Alley: Deep time is something much older than us, far beyond written history. It encompasses the vast expanse of 4.6 billion years of Earth's existence. If you visit the Grand Canyon, you'll see a massive trench with a river at its base. It's easy to think the world is as young as written history, but that would be a misconception. How could the river be down there when we can see its constant erosion of the landscape? People have been visiting the canyon for centuries, documenting their experiences, and native peoples have been there for thousands of years. In that time, the canyon has changed, but not dramatically. So, why is the river down there? By considering deep time, one can visualize a process as slow as removing a sheet of paper from rock every year, which would be enough to carve the canyon over millions of years. This allows us to appreciate the immense timescale needed to form such features.

But deep time doesn't just help explain how the canyon was carved—it also gives us the context to understand the formation of the rocks themselves. These rocks hold vast stories, and when you visit the canyon, you can tap into that deep time perspective. If you only live in shallow time, you might simply look at the canyon and admire its beauty, thinking it would make a nice picture or postcard. However, if you live in deep time, the canyon becomes a rich tapestry of stories. You can imagine the seas rising and receding, envision a lizard running across the back of a fossilized sand dune, and picture the cliffs, where lizards once roamed. The very presence of sand dunes in the past raises questions about why they were there in the first place.

These incredible stories surround you. If you spend enough time there, you might find yourself lost in these thoughts for hours, not rushing to the gift shop or heading off to Las Vegas. Instead, you remain captivated by the grandeur of deep time, its beauty and mystery unfolding before your eyes.

[Text on Screen: Deep Time and Beliefs]

Dr. Richard B. Alley: I do think it's difficult for people to conceive of the immense age of the Earth for several reasons. One of the main challenges is that if you are a literal believer in certain sacred texts, you may believe that the Earth is no older than written history. As a geologist, my predecessors in the 1700s faced this same dilemma. These were individuals who truly believed in sacred books while also studying the rocks and trying to make sense of them. Some of them ended up rejecting the evidence in the rocks, while others renounced their religious beliefs. However, many found a middle ground, acknowledging that it was possible to be both religious and accept the evidence in the rocks. They proposed that the days mentioned in the Bible could be longer than 24 hours, offering a compromise between science and faith.

People who interpret certain sacred texts literally, word for word, simply cannot accept the age of the canyon. I, on the other hand, am a religious person myself, and I don't wish to impose my beliefs on anyone. I belong to a very large religion with millions of members, and within my faith, there is no conflict with accepting the age of the canyon.

[Text on Screen: Deep Time and Change.]

Dr. Richard B. Alley: If you want to ask whether nature will undo what humans are doing to the world, the answer involves understanding our actions and their consequences. We're burning fossil fuels, taking carbon out of them, and releasing it into the atmosphere. This is changing a lot of things—how easily plants breathe, how well marine life like clams and corals can form shells, the climate, and much more. The question is, how rapidly will nature undo these changes? To answer that, we have to look at how quickly nature has acted in deep time. We know that nature has altered the levels of carbon dioxide in the atmosphere many times throughout Earth's history. For example, the dinosaurs lived in a world with much more carbon dioxide than we have today, and they thrived in that environment. It was a warm world with no ice sheets at the poles—crocodiles lived near the North Pole, palm trees grew in Wyoming, and many other species adapted to the warmth.

However, the change from a low-carbon dioxide world to a high-carbon dioxide world took nature about 100 million years, and we're attempting to do it in just 100 years. So, is it likely that nature will undo the damage we're causing in a time frame that we would notice? No, it's not. This illustrates how rapidly the world works by itself compared to how quickly we are changing it. Therefore, understanding deep time is crucial for answering questions like this.

[Text on screen: Deep Time and You.]

Dr. Richard B. Alley: There are things that matter to you that come from deep time, which is one reason we have a geosciences department at Penn State. For instance, if you're a geoscientist who has completed your undergraduate degree and you're hired by an oil company, your job might be to determine whether or not they should drill an oil well at a specific location. We know that oil is created by cooking dead organic material, mostly dead algae. You also know that oil is flammable—if you’ve ever had oil in your engine and it overheated, you’ve seen how oil burns up. If rocks have been too hot in the past, you won’t be able to extract oil from them.

To figure out whether oil can be found in certain rocks, you need to know if the rocks have been hot enough to cook the organic material but not too hot to break it down. You also need to understand what happened to those rocks over time. This involves knowing how deeply the rocks have been buried, how long they remained down there, how long it took them to return to the surface, and their overall path through time, temperature, and space. This knowledge of deep time is essential. Some rocks won't yield oil because they were heated too much, leaving only a bit of carbon or graphite behind—no oil to be found. Therefore, it’s crucial to understand the history and conditions these rocks have experienced.

[Text on screen: Deep Time and You Part 2]

Dr. Richard B. Alley: Knowledge of evolution plays a crucial role in understanding many aspects of life, including the challenges we face with diseases. For example, AIDS and antibiotic-resistant bacteria were bound to happen because living organisms are survivors, and they have the ability to adapt if their environment changes. We have to stay ahead of these changes by being smart, because evolution is a slow process—it takes hundreds or even thousands of generations. Modern humans haven’t existed long enough for evolution to have much of an impact on us in a short time.

Personally, I have bad eyesight, and I’ve probably passed that on to my children. However, physical evolution doesn’t really matter much in this case because we solve problems like this through intelligence. I don’t worry about being eaten by a saber-tooth tiger, partly because there aren’t many of them left and partly because I wear glasses. We outsmart the problems that evolution doesn't address quickly enough, but for organisms like bacteria, which reproduce every 20 minutes, evolution happens rapidly. Understanding evolution and its impact is crucial because it affects us. If you're not an expert in what bacteria, viruses, or diseases like the flu are doing, and how we can adapt when they change, you're likely to be caught off guard in the next pandemic.

If we have brilliant minds working on developing new antibiotics, vaccines, and strategies to deal with these evolving threats, we can continue to live happy, healthy lives. This knowledge of deep time is essential for addressing many issues, whether it's oil, environmental concerns, or the ever-evolving diseases we must face. Deep time matters because it helps us understand the long-term processes that shape life on Earth.