Conversation 36

Listen to a conversation between a university student and a professor in the professor’s office.

S: Hi, Professor LeGore. My name’s Susan Coats. I have a 10 o’clock appointment.

P: Yes, Susan. Come in, sit down. What can I do for you this morning?

S: I had a, uh, question about Tuesday’s lecture on pla [false start] on plate tectonics. My notes aren’t too clear. I was wondering if I could, um, ask you a little more about it.

P: You sure can! In fact, I’m glad you’re here. Remember what I said at the beginning of the term, the only bad question is the one that stays in your brain. Right?

S: Yeah. Thank you. Uh, anyway [clears throat]. Well, I didn’t quite get the differences between divergent and convergent boundaries of tectonic plates, and what happens when they crash, or uh, bump into each other.

P: OK. You, uh, know that there are four major types of boundaries on tectonic plates, right? And when tectonic plates move and bump into, or uh, rub against each other, it creates effects on the land above, such as creating mountains, causing earthquakes, forming new continents and stuff like that. Good so far?

S: Yeah, I understand that. That’s why the Earth’s topography keeps changing over time, and why North, er, South America pulled apart from Africa. Now, you said that the plates, with con, no, divergent boundaries, when they collide, one of the plates goes under the other one?

P: No, you’re mixing them up. That happens with convergent boundaries. One of the plates tends to submerge under the other one, which destroys the Earth’s crust. When divergent boundaries collide, the two plates pull away from each other, which creates new crust.

S: Oh, I see. So convergent boundaries submerge and destroy crust, and divergent boundaries pull apart and form new crust. I think I’ve got it.

P: All right. So, um, let’s test your knowledge. In the past few million years, the country of Saudi Arabia has separated from Africa, which has helped form the, uh, Red Sea. Is this the result of a collision between divergent or convergent boundaries?

S: Um…that would be, uh, divergent, wouldn’t it? Because Saudi Arabia is pulling away from Africa and creating something new: the Red Sea.

P: Yes, very good Susan. Now, at the border of India and Asia, there are the highest mountains on the face on the Earth, including Mt. Everest. What caused those?

S: A convergent boundary! The plates of India and Asia collided, and one plate dove under the other one, pushing up the crust into mountains.

P: Excellent, young lady! I think you are getting the hang of this.