Tabular sills and lava flows often have regular geometric grids of vertically oriented, thermal shrinkage cracks called_______ .
A) hot flashes
B) arthritic joints
C) honeycomb fractures
D) columnar joints

Question

Quizplus · Accepted Answer

Columnar joints are the result of thermal shrinkage in cooling lava or magma, which leads to the formation of regular, often hexagonal, columns perpendicular to the cooling surface.

Tabular Sills and Lava Flows Often Have Regular Geometric Grids