Do geologists know what they’re doing?

I got an exceptionally apt question a while back on my GeoMania website: “Are geologists sure that they’re right about how the earth works?” This is a tough one to respond to without sounding arrogant or full of the stinky stuff, but I’ll do my best to avoid both…

The earth has been evolving for an incredibly long time — at least relative to our human time frame. It’s also extremely massive. As Newton confirmed nearly five hundred years ago, the bigger something is, the harder it is to get it to change. Try to imagine the mechanical and thermal forces necessary to affect something as massive as the earth. They must be incredibly powerful. In addition, it seems as though they would also have to act VERY slowly – any power this great would rip the earth to shreds if it happened too fast.

So what we have are immense forces acting at a slow but very persistent rate. As scientists, how can we duplicate this in the controlled laboratory setting that is required if we want to be considered real scientists, and in the process learn something about how our planet works?

Take traditional, high-grade metamorphic rocks for example: We assume that the profound changes in mineralogy are the result of deep burial of previously formed rock, leading to an increase in temperature and pressure. As scientists we have great furnaces and can achieve the same temperatures in a lab — no problem here! We also have great presses to simulate an increase in pressure. We can even do “heat and pressure” together. So far so good. But the earth does the same thing, and keeps it in the pressure cooker for millions of years. This we can’t do, and I doubt we’ll ever be able to duplicate the “geologic time” variable in the lab.

In any event, “are geologists sure?” was the ask. Actually, we can’t know much of anything FOR SURE. This uncertainty can be the curse — or the blessing — of any study of the earth. But we CAN look at the way earth processes work (see the Laws of Geology), compare those processes to the rocks and such exposed at the current erosional level, and GeoFantasize about what might be happening (click here for a post on the Laws of GeoFantasy).

GeoFantasy is great, and is a hobby you can take with you everywhere you go. Never hesitate to make up GeoFantasies about what you see. Sometimes you’ll be right, and a lot of times you’ll be wrong, but all the times you’ll get something positive out of the effort. Just don’t get cocky and start believing your ideas too much. Belief in geology is like a weather forecast – it’s based upon percentages. A good geologist is rarely 100% sure of anything. Remember the last two steps in my version of the scientific method, and keep an open mind.