Basalt Columnar Jointing
The
rocks of Heilong Wall have
unique appearance, most of which have nearly
hexagonal plane of fracture, and belong to typical
basalt columnar jointing. Columnar jointing is the cracks formed from homogeneous
lava when it contracts evenly during cooling process, and is common in basalt. Between the each two stone columns in column group, there is
a perpendicular fissure almost penetrating through the upper and lower surface.
When the top and bottom of lava flow contracts at the same time, the jointing
in the upper part divided column group into lower columnar jointed colonnade
and upper entablature. There are lots of stones scattering at the bottom of
Heilong Wall because the abundant joints and cracks in the lava of Heilong Wall
led to the rock blocks to be unstable, collapse and fall.