The tall polygonal features preserved in the ancient basalt flow in the image below formed because the lava ________.

A)was moving as it cooled,so it fractured
B)erupted underwater and cooled rapidly,forming many fractures
C)was subjected to shaking from earthquakes,and subsequently fractured
D)shrank as it cooled,forming tall polygonal-shaped fractures

Question

The tall polygonal features preserved in the ancient basalt flow in the image below formed because the lava ________.

A)was moving as it cooled,so it fractured 
B)erupted underwater and cooled rapidly,forming many fractures 
C)was subjected to shaking from earthquakes,and subsequently fractured 
D)shrank as it cooled,forming tall polygonal-shaped fractures

Quizplus · Accepted Answer

The statement "shrank as it cooled" indicates that the lava underwent cooling induced contraction, which caused it to split into tall polygonal-shaped fractures. Therefore, option D is the best choice.

The Tall Polygonal Features Preserved in the Ancient Basalt Flow