Ultramafic Lava Flows Were More Common in the Early History

question 18

Multiple Choice

Ultramafic lava flows were more common in the early history of the earth than now because

• A)ultramafic melts were more common in the past.
• B)Earth's crust was hotter in the past.
• C)Earth's mantle was cooler in the past.
• D)plate tectonics had not been initiated.