What is the topic of the talk?

Welcome. It looks as if everyone who’s coming is already here, so let’s start, shall we? In yesterday’s class, I talked about how the Earth and the Moon are thought to have formed. As I told you, the best theory concerning their origins seems to be the "Single Source" theory. This states that the Earth and the Moon were made out of the same ball of molten mass. I also talked about how the Earth eventually cooled down and how its surface features formed. And just before the end of the class, we looked at how all the continents were fused into one gigantic continent called Pangea. Now, to continue from where we left off, we know for certain that this massive continent did not last forever - just look at a present-day globe. According to current theories regarding continental drift, this huge landmass probably began to fracture into the continents we see today about 200 million years ago. This date is supported by the ages of basalt flows that have been found in the middle of the Atlantic Ocean. It is likely, by the way, that the Atlantic did not form immediately after Pangea’s breakup, but I’m getting way ahead of myself. Right now I want to show you a short video about Pangea. After that, I’ll talk about the oceans.