The previous post briefly discussed the notions of ‘clock time’ and ‘event time’ in the context of geological thinking. (Note that I’m using and instead of versus — I don’t think we need to pit these against each other in a way that implies a dichotomy.) For this post I’d like to explore the idea what an ‘event’ is in the context of the multiscale temporal reasoning common in geoscience and Earth history. As always, these blog posts aren’t meant to be a comprehensive and exhaustive treatment — the spirit of this is simply to share some thoughts as I read and learn.

What defines an ‘event’? A straight-up google definition is: “a thing that happens, especially one of importance”. Perhaps we could add to this with specifying that an event has a beginning and an end — that is, it is a discrete ‘thing that happens’ in the context of time such that you experience the before, during, and after. For example, we typically don’t refer to a permanent change as an event. But, as I’ll get into below, what’s temporary and what’s permanent can depend on the temporal perspective.

I was recently reading this fantastic 2020 review about paleoclimate research in Science by Jess Tierney and coauthors and decided to use a famous and well-studied Earth history event — the Paleocene-Eocene Thermal Maximum (PETM) — as the inspiration for the example below. That is, what I show below is not strictly based on PETM specifics, think of it more as a generic example to illustrate a broader point.

Okay, let’s set this up. I’ll show a bunch of plots like the one below where time is on the horizontal axis and showing elapsed time progressing from left-to-right. The vertical axis is some ‘change’ in the most generic sense, it could be anything. (For example, in the context of paleoclimate, it might be the values of a measurable proxy that is used to represent temperature, atmospheric CO2, etc.) This first view shows a ‘spike’ occurring at ~1 million years. I think we would all agree this is an event with a beginning and an end, and a clear signal of temporary change in context of background conditions.

Now, let’s ‘zoom in’, in a temporal sense, by changing the horizontal axis to show this event over 150,000 years in the plot below. (If I had the coding skills I would’ve built an interactive widget for you to zoom in/out however you like but, alas, I am not so skilled!) At this scale we can see the ‘shape’ of this event. There is an abrupt beginning and a gradual transition from the peak change back to the pre-event condition.

In the lingo of paleoclimate, we might say that this event has a rapid onset and gradual recovery. In this case, the duration of the onset is only ~5% of the duration of the entire event. This is just one shape, of course. You could envision it in reverse, symmetrical, and so on.

Let’s temporally zoom in more, to the beginning of this event. The plot below shows approximately 10,000 years of time and focuses on that initial change, or onset. Here, we can see that the initial change — going from the baseline to the peak — occurs over 6,000 years. Is 6,000 years ‘rapid’? Additionally, if this was the only temporal perspective we had, would we call this an ‘event’? From this view, this looks like a permanent change.

One of the key timefulness skills is the ability to mentally zoom in and out like this with relative ease. Like any skill that eventually feels natural, it takes practice. Perhaps an additional way to practice is to transpose these geological timescales (millennia to millions of years) to timescales relevant to human experience.

The plot below is the exact same event as above, but with the horizontal (time) axis now in years. Thus, instead of the total duration as 130,000 years, we are considering this change over ~13 years. For adult humans this is a duration that has a ‘feel’ to it. Just as in the PETM-inspired event above, this change as a rapid onset and a gradual transition back to baseline.

We could then zoom in more just as we did above and see that the initial change for this ‘event’ occurred over ~7 months. Again, is seven months ‘rapid’? The obvious quick answer to these questions is, of course, ‘it depends’.

This notion of dependence on timescale-of-investigation is not a new idea in geoscience, of course. These ideas are deeply ingrained in our science and show up in many forms and in numerous contexts. To circle back to the Tierney et al. (2020) Science paper, they make the following statement near the end of the paper regarding temporary changes in climate:

Earth has the ability to recover from a rapid increase in atmospheric CO2 concentration — the PETM is a textbook example of this process. Indeed, in every case of past CO2 perturbation, the Earth system has compensated to avoid a runaway greenhouse or permanent icehouse. Yet the natural recovery from aberrations takes place on geological, not anthropogenic, time scales.

Emphasis mine. They are making this critical point about timescales of Earth-system recovery because the audience, the reader, of their paper may not be as familiar with (or skilled at) adjusting their temporal perspective.

Those that are accustomed to thinking in this multi-timescale way — that is, those that have developed timefulness skills — might consider my examples above as obvious or even trivial. And that, I think, is the point. Could the type of thought exercises above that transpose longer timescales to the range of timescales that humans experience help people develop timefulness? I suspect that many geoscience instructors are already doing things like this in innovative and clever ways, but perhaps in an embedded or implied sense. I’d like to suggest that we be more intentional and highlight temporal reasoning when it is an important aspect of a particular lab activity, problem set, or project. And, in some cases, develop new activities/projects in which temporal reasoning is elevated, where it is the primary learning outcome.

I plan on using future posts to ponder this further and to, hopefully, develop some tangible ideas to use in my teaching. One quick idea to end this post: I could break students into small groups, give each group a different temporal view of some change (the different plots above), ask them to characterize it with both language and quantitatively, and then we convene as an entire class to discuss the differences.

How do the different ways we perceive time influence how we think (and learn to think) about deep time? As I mentioned in a post last week, a goal I have in 2021 is to read and learn about how humans perceive time with a specific focus on connecting that to how geoscientists develop ‘timefulness’. I’ll get into how Marcia Bjornerud explains timefulness, and my own reflections about what it means, in a future post. For now, consider timefulness as a mindset that is not just ‘deep time’ thinking, but the ability to connect multiple timescales, spanning the continuum from human experience to geological, to the present and with an eye on the future. In his book Deep Time Reckoning, cultural anthropologist Vincent Ialenti puts it this way:

“Learning to hop more nimbly around these timescales can inspire a more refined multiscale, multiangle, or multiperspective sensibility. This kind of multidimensional thinking must, I suggest, be cultivated during the Anthropocene.”

Yes, to hop around timescales — or, put another way, the ability to temporally zoom in and out. I’m interested in how geoscientists develop this skill and how we can more effectively facilitate others — students, each other, our communities — to learn and apply timefulness to the big challenges we face.

For this post, I wanted to briefly explore the related ideas of clock time and event time. In a social/cultural context, this is typically thought of as cultures and societies that tend towards operating by the clock versus measuring time primarily by social events. Both are, of course, in operation depending on the context. Work-related meetings are very much on clock time in my world — they start and (hopefully) end at specific times. Those running the meeting will even say things like “We only have a couple minutes left and I want to respect everyone’s time, so let’s stop here.” In contrast, a social gathering may have a clock-time beginning (although communicated with some looseness; e.g. “Come by anytime after 6pm”) but in many cases does not have a clock-time end. People leave at different times depending on their circumstances and, at some point, the event (the party) ends because it “feels” over.

“090421 Watch” by steeljam is licensed under CC BY-NC-ND 2.0

We can apply this notion to geology and Earth history and to the thought processes that goes into reconstructing past conditions and events. The geologic timescale itself is a combination of event time and clock time. Boundaries between the named divisions of the timescale are, in most cases, based on the “event” that is the disappearance of notable fossils. While we have incorporated clock time (absolute ages), a task that is seemingly never ending as our geochronological tools improve, it’s important to remember that the geological timescale stands on event time. Marcia Bjornerud has an interesting passage in Timefulness about this idea in the context biologists applying molecular clock approaches to Earth history and how those findings are not always consistent with conclusions from paleontologists:

“The disagreement reveals interesting cultural differences between field-based paleontologists, who, inured to the idiosyncrasies of fossil life, are willing to embrace the idea of nonsteady rates of evolution, versus lab-based molecular biologists, who see mechanism in cellular structure and are more orthodox uniformitarians than their geologic counterparts.”

Event time and clock time is embedded in much of the research I do and am interested in. For example, we’ve been working on the sedimentology and stratigraphic architecture of outcropping Cretaceous deep-marine deposits in southern Chile for almost two decades now. Some of the work is clearly using an event-time framework in that the objectives of the research don’t require clock time to make a contribution and provide insight into, for example, fundamental processes. Indeed, a lot of physical stratigraphy research is perfectly comfortable in a relative timescale that reconstructs the order and character of events but need not assign ages to them.

But then there’s other research that does require clock time. For example, testing hypotheses about how specific tectonic or climatic events (that are well established in clock time) requires knowledge of the absolute ages. We published a paper a couple years ago that was singularly focused on sharing with the community a refined ‘clock time’ for this specific place and time in the geologic past (the phrase ‘chronostratigraphic framework’ is arguably just jargon for ‘clock time’).

And if the science is rooted in understanding the rates of processes then, of course, we need to be thinking in clock time. Numerous disciplines in geoscience have elevated questions related to rates — whether it’s landscape change, biological evolution, climate transitions, tectonic processes, and more — among the most important questions for the community to address.

I’ll close with a final thought: What is an ‘event’? The example of the party mentioned above is fairly clear cut — it has a beginning and an end and would be a discrete ‘thing’ in your memory. But, what about when an event is stretched out over time? As I write this (January 2021) we are still in the midst of a pandemic that, in the U.S., will soon be a year long. Our future memory of this may think of it as an ‘event’, but when exactly did it begin? And the ‘end’ of it will certainly not be a single moment or day on the calendar. However, historians a century from now will likely talk about what feels like forever to us as a discrete event. Events in the geologic past, whether it’s a few thousand years ago or hundreds of millions of years ago, aren’t so different. I’ll explore this idea of events in the context of temporal reasoning more in a future post.

Remember blogs? Back in the 2000s and into the early 2010s, the ‘weblog’ venue for writing and sharing on the internet was quite popular, spawning various networks and grass-roots communities of people with shared interests. It was a whole thing. This was when I was in graduate school and the first few years after my Ph.D. and I found it to be both an enjoyable way to share and learn and also a vehicle for writing about science that wasn’t a technical paper/proposal but also not trying to be journalism or public outreach. I miss that outlet.

So, for 2021 I’m going to attempt to reengage with this style of writing as a way to ‘stretch those muscles’ a bit. I thought about doing this at the original site, but decided to make my life simpler by just using this research group website and identifying as a Clastic Detritus blog post with my ‘classic’ banner image and disclaimer at the top. I’m not going to be overly ambitious about it, I’m aiming for approximately one post per month. It’s an experiment, we’ll see how it goes! (I’m not going to have a comment thread as it would likely attract spam/trolls; you can find me on Twitter or reach out via email.)

A potential theme for some of the posts this year is exploring how geoscientists think about time. Over this recent holiday break, I reread the wonderful 2018 book Timefulness by Marcia Bjornerud and also read a fantastic new book by Vincent Ialenti called Deep Time Reckoning. Both books have similar subtitles: “How thinking like a geologist can help save the world” and “How future thinking can help Earth now”. Both of these works articulate one of the most valuable aspects of ‘deep time’ thinking common in geoscience — how studying longer timescales and reconstructing Earth history is critical for understanding our present and for thinking about our future. Not a new idea, to be sure, but these two books have refreshing takes on this notion in my opinion. Thus, I’ll likely write future posts about both of these.

As I’ve progressed in my own teaching, course development/design, and interaction with students, I’ve become increasingly interested in how we, as geoscientists, think about time. It’s not merely an appreciation for the vastness of Earth’s history or gaining knowledge about important processes that occur at very long timescales. Geoscientists also have the ability to consider a huge range of timescales, and can ‘zoom in’ and ‘zoom out’, temporally, with relative ease. We can intuitively identify and focus our thinking on a specific range of timescales for a certain question or problem. Indeed, these and similar are among the skills that Bjornerud has coined as timefulness. Deep time (long timescales and the distant past) is a key part of timefulness, but there’s more to it.

But, how do we generate this intuition? That is, how do students and novice geoscientists develop timefulness? And, how can I improve my teaching (and mentoring) to enhance that development? There’s a rich field of time-perception research as well as work by education researchers focused specifically on temporal reasoning to draw upon. For example, this GSA Special Paper from 2012 has several of insightful articles from geoscience education researchers about teaching and learning related to geologic time. My goal isn’t an exhaustive treatment of everything there is to know — I’m not an education researcher or cognitive psychologist and don’t pretend to be. My aim isn’t to write scholarly pieces suitable for journals — my goal is simply to share some aspects I found interesting in my own exploration and learning.

Again, getting back into this more stream-of-consciousness and ‘low stakes’ style of writing is an experiment. Maybe it gathers some momentum, maybe it fizzles, stay tuned. The first real post (in a few weeks time) will be about one, or maybe both, of the books mentioned above: Timefulness and Deep Time Reckoning.