TOEFL Listening: ETS-TOEFL听力机经 - MR42F4ANYA2P5E6SP$

What unexpected discovery did scientists make while studying the rift event in East Africa? A. Rifts can widen more quickly than previously thought. B. Some magma deposits lie closer to Earth surface than geologists realized. C. Volcanic activity is not necessary for rift formation. D. Volcanic activity along land rifts is different from activity along underwater rifts.