When continental crust begins to pull apart at a divergent boundary, a sequence of geological events eventually creates an ocean basin. In what chronological order do these developmental stages occur from first to last?
- 1Continental crust stretches, thins, and fractures to form a central rift valley.
- 2The widening rift valley subsides below sea level and floods, creating a narrow, linear sea.
- 3Continuous seafloor spreading produces new oceanic crust, developing a wide, mature ocean basin.
Answer
The correct chronological sequence begins with continental crust stretching and fracturing to form a rift valley, followed by flooding to form a narrow linear sea, and concludes with long-term seafloor spreading forming a mature ocean basin.
Divergent boundary evolution begins when upwelling thermal currents pull continental crust in opposite directions, causing normal faulting and a rift valley (such as the East African Rift). As divergence widens the gap and lowers the elevation, seawater floods the valley to form a long, narrow linear sea (such as the Red Sea). Continued seafloor spreading along a central mid-ocean ridge continuously adds basaltic crust, eventually forming an expansive, mature ocean basin (such as the Atlantic Ocean).
Step-by-Step Solution
Key Concept
Evolutionary sequence of divergent plate boundaries from continental rifting to mature ocean basin development
Estimated Time:45s