Choosing Your Scale: Lessons From the Field

There are many skills that can be learned by reading, but being a field scientist is learned almost exclusively by doing. Reading and coursework give us a strong foundation and help develop the associative pathways that connect what we’ve learned to what’s in front of us. But they don’t prepare us for all the uncertainty and messiness of real-world situations.

I remember my first field course. I had read all the textbooks twice over, and I was an outdoor enthusiast. In the van on the way to the first outcrop, I was jittery with anticipation and eager to prove myself as a field geologist. I had rehearsed in my mind what information I would need to record and how to record it. In my courses I had practiced each skill on its own. I had drawn rocks and described them, taken practice strike and dip measurements, learned about unconformities, and memorized characteristic packages of rock like turbidites. I was ready!

But when we reached our destination and I stood in front of a rock face, not as a climber or mountaineer but as a geologist, I froze. Everything I had learned came flooding in at once, and I had no way of sorting what mattered in that moment from what didn’t. Should I be pulling from GLGY 202, or 205, or 404? I was still standing there, frozen, when my teacher brought me back with one simple, grounding instruction: “Everyone start hammering, and someone tell me what type of rock we’re looking at.”

Simple-ish! But it reset everything. I had arrived expecting a test, ready to prove I had the answers. What we were actually doing was starting at the beginning. The point wasn’t to work through a checklist of questions (although our teacher gave us plenty of those). The point was to explore, look closely, and let the rock tell us where to go next. That shift from answering to discovering is where I started becoming a field scientist.

Choosing your scale

The first real skill I had to learn was deciding what scale to observe an outcrop at, and when. Should I look at a map to see where we are regionally and how the surrounding topography fits together? Should I have my face nearly touching the rock, looking for sedimentary structures or fossils? Or should I step back and take in the whole outcrop, so I can see the fractures and how it relates to the material around it?

The answer, slightly unsatisfying as it is, is that it depends. It depends on what you’re trying to discover, what information you need the rocks to give you, and how much time you have.

I froze at that first outcrop because I expected to discover everything the rock had to offer in 20 minutes. That’s an entirely unrealistic expectation. People can, and have, spent whole careers studying a single formation or even a single outcrop.

So my first piece of advice is to approach each outcrop knowing the scale (or scales) you need to work at to answer the questions you came with. My second is to accept that there’s always a trade-off. If you spend your time at one scale, you’ll miss what’s held at the others. If you try to cover every scale, you’ll miss the detail at all of them. That’s the reality of fieldwork, and honestly of life. So ask yourself: what information do I absolutely need, at what level of detail, and what can wait for another day?

Before I approach any outcrop, I ask myself:

1. What is my research question?

2. What information do I absolutely need from this outcrop to answer it?

3. What information is secondary and can be collected if there’s time?

4. At what scale do I need to observe the outcrop to capture that information?

5. What are the strengths of my field methods?

6. What are the trade-offs, and will they affect the outcome of my research? How?

7. How will my field methods bias my data?