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The Earth's plate boundaries are most often on the floor of the oceans. The masses of the continents are on the plates.

Earth science reality check

by Meghan Leach
Nov 06, 2012


Expedition 30 on ISS/NASA

In Kenya, a new plate boundary is emerging, as shown in this NASA photo from the International Space Station.

Common earth science misconceptions

Volcanoes were always erupting in the time of the dinosaurs.
The continents don’t move.
Landscapes don't change, or change so slowly that we can’t see it.
All rocks are hard.
All rocks are hard. The continents stay put. It sounds sensible. But it’s bogus, like other common science misconceptions people harbor.

George Davis, a geoscientist at the University of Arizona, discusses some of the most routine earth science misconceptions he has encountered.  Here’s his reality check.

Q: Have you heard the misconception that volcanoes all violently explode?

Davis: With respect to volcanoes, I think the perception that people might have based upon visiting museums throughout the world is that every time a dinosaur was walking around the Earth there was an erupting volcano in the background, and yes, erupting explosively.

I haven’t personally run into the kind of nuances of volcanoes from the public, for example thinking that they are all explosive and that some of them are not quiet. That may exist out there, but I haven’t stumbled across it.

Q: Another misconception I heard is that the continents don’t move.

Davis: Any time we explain plate tectonics and plate motions, or maybe show an animated video that quite clearly reveals how things have been moving in the last 200 million years, it’s a show stopper for people. That is they really react. Particularly with the videos, they understand in about 20 seconds what it’s all about, and it changes their perception.

Given the striking nature of the response to either taught descriptions of plate tectonics or video animations, it seems clear that most people start with a sense that the continents on which they are living and standing are not moving.

I think a corollary misperception that is rampant, and one that is really difficult to disabuse, is that plate tectonics is all about the motion of continents as individual masses and not plates of which the continents are a part. The plate boundaries are not where you expect them to be.  You would expect them to be right at the edges of continents—they’re not always there.

Q: Are there other misconceptions you come across?

Davis: The perception that landscape doesn’t change; that it remains fixed. The false perception is that everything in terms of landscape change is incremental and small when in fact erosion in particularly mountainous areas is taking place in giant bites.   

There were, after a few really wet summers - wet for Tucson - these mudflows that took place in this canyon. They were sudden, and they really changed the local topography. They wiped out some small built structures. 

People were amazed how much the topography and the landscape can change over night. But the misperception was overwhelmed by the fact that they saw change in a location that they were utterly familiar with. It’s not like watching it on TV.

Q. What is a misconception students often have?

Davis: I like to persuade my students to become comfortable saying, ‘soft as a rock.’  When they start getting comfortable with that, I know I’m home free. 

If you pick up a rock that’s on your desk, or a cobble out of a stream, of course, it’s hard. But rock layers are really soft. No matter where you go around the world in mountain belts everything is just tossed and turned and folded and folded and sheared and bent and broken. You can deform these materials effortlessly.